WO2005050656A1 - Internal voltage reference for memory interface - Google Patents
Internal voltage reference for memory interface Download PDFInfo
- Publication number
- WO2005050656A1 WO2005050656A1 PCT/US2004/036825 US2004036825W WO2005050656A1 WO 2005050656 A1 WO2005050656 A1 WO 2005050656A1 US 2004036825 W US2004036825 W US 2004036825W WO 2005050656 A1 WO2005050656 A1 WO 2005050656A1
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- WIPO (PCT)
- Prior art keywords
- switch
- pull
- coupled
- calibration
- voltage reference
- Prior art date
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Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C5/00—Details of stores covered by group G11C11/00
- G11C5/14—Power supply arrangements, e.g. power down, chip selection or deselection, layout of wirings or power grids, or multiple supply levels
- G11C5/147—Voltage reference generators, voltage or current regulators; Internally lowered supply levels; Compensation for voltage drops
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C2207/00—Indexing scheme relating to arrangements for writing information into, or reading information out from, a digital store
- G11C2207/22—Control and timing of internal memory operations
- G11C2207/2254—Calibration
Definitions
- Embodiments of the invention relate generally to voltage reference generation, and specifically to internal voltage reference generation for a DDR memory interface.
- a voltage reference may be generated externally and coupled into an integrated circuit (IC) through a dedicated voltage reference pin or terminal of a package for use by circuits therein.
- the semiconductor die of the IC has a dedicated voltage reference pad to couple to the voltage reference pin or terminal of the package.
- the use of a dedicated voltage reference pin or terminal of a package increases the package costs. Additionally, the use of the dedicated voltage reference pin or terminal also increases the costs of the semiconductor die of the IC by accommodating the dedicated pad for the external voltage reference.
- Figure 1 illustrates a block diagram of a typical computer system in which embodiments of the invention may be utilized.
- Figure 2A illustrates a block diagram of a central processing unit in which embodiments of the invention may be utilized.
- Figure 2B illustrates a block diagram of another central processing unit in which embodiments of the invention may be utilized.
- Figure 2C illustrates a block diagram of a memory module including memory devices with output drivers that may be calibrated by a memory controller.
- Figure 3 illustrates a block diagram of elements to perform off chip driver (OCD) pull-up calibration and off chip driver (OCD) pull-down calibration in a memory controller .
- OCD off chip driver
- OCD off chip driver
- Figure 4 illustrates a block diagram of the concept of internal voltage reference generation using OCDH and OCDL calibration terminals/pins.
- Figure 5A illustrates a block diagram of the switch settings for generating an OCD pull-up calibration voltage in OCD mode.
- Figure 5B illustrates a block diagram of the switch settings for generating an OCD pull-down calibration voltage in OCD mode.
- Figure 5C illustrates a block diagram of the switch settings for internal voltage reference generating for normal mode .
- Figure 6 illustrates an exemplary schematic diagram of transistor switches to provide OCD calibration voltages in OCD mode and an internal voltage reference in a normal mode.
- Figure 7 illustrates a block diagram of a packaged integrated circuit without an external voltage reference terminal/pin .
- Embodiments of the invention eliminate an external voltage reference (VREF) , the external voltage reference (VREF) pin/terminal from the package, and an external voltage reference pad on the semiconductor die by generating an internal voltage reference VREF from other pins/terminals typically used to perform Off Chip Driver (OCD) calibration.
- VREF external voltage reference
- OCD Off Chip Driver
- a pair of calibration pins/terminals are used to provide a voltage or impedance to calibrate output drivers driving memory devices that support a double data rate (DDR) II specification, described in a JEDEC Standard JESD79-2 "DDR2 SDRAM SPECIFICATION", September 2003 by the JEDEC Solid State Technology Association.
- DDR double data rate
- one calibration terminal/pin is a reference for OCD pull-up calibration while the other calibration terminal/pin is a reference for the OCD pull-down calibration.
- These calibration terminals/pins are used during initialization or periodic calibration when the memories are not available.
- the internally generated voltage reference (VREF) is not used by the input receivers of the memory controller to receive data.
- the internal voltage reference VREF may be generated and used at the digital input receivers to receive data.
- the internal voltage reference VREF is used to compare against an incoming digital data signal to make a determination as to whether or not the input signal is a logic level zero or a logic level one. That is, the voltage level of the internal voltage reference VREF acts as a trip point or switch point.
- An input signal with a voltage level above the trip point is a logic level one and an input signal with a voltage level below the trip point is a logic level zero, for example.
- an integrated circuit to interface to memory is disclosed.
- the integrated circuit includes a first off chip driver calibration terminal to couple to an external pull-up resistor; a second off chip driver calibration terminal to couple to an external pull-down resistor; a first switch coupled between the first off chip driver calibration terminal and a voltage reference node; and a second switch coupled between the second off chip driver calibration terminal and the voltage reference node.
- the first switch and the second switch are selectively closed to generate an internal voltage reference on the voltage reference node with which an input signal may be compared in order to receive data; the first switch is selectively closed and the second switch is selectively opened to generate a pull-up calibration voltage on the voltage reference node to calibrate an off-chip driver; and the first switch is selectively opened and the second switch is selectively closed to generate a pull-down calibration voltage on the voltage reference node to further calibrate the off-chip driver.
- a method in an integrated circuit for interfacing to a memory including if in an off-chip driver calibration mode for a pull-up, then selecting a pull-up calibration terminal to be coupled to a voltage reference node to provide a pull-up calibration voltage thereon, and calibrating a pull-up of an off chip driver; and if in an off-chip driver calibration mode for a pull-down, then selecting a pull-down calibration terminal to be coupled to the voltage reference node to provide a pull-down calibration voltage thereon, and calibrating the pull-down of an off chip driver; and if in a normal mode to receive data, then selecting the pull-up calibration terminal and the pull-down calibration terminal to be coupled to the voltage reference node to provide a reference voltage thereon, and receiving data from a data input terminal .
- a system including a processor for executing instructions and processing data; a double data rate memory device to store data from the processor and to read data to the processor; an external pull-up resistor having a first end coupled to a first power supply terminal; an external pulldown resistor having a first end coupled to a second power supply terminal; and a memory controller coupled between the double data rate memory device and the processor.
- the memory controller has a pull-up calibration terminal coupled to a second end of the external pull-up resistor, a pulldown calibration terminal coupled to a second end of the external pull-down resistor, a voltage reference node, a first switch having a first switch connection coupled to the pull-up calibration terminal and a second switch connection coupled to the voltage reference node, and a second switch having a first switch connection coupled to the pull-down calibration terminal and a second switch connection coupled to the voltage reference node.
- a processor for a computer system including a memory controller to interface to memory.
- the memory controller has a pull-up calibration terminal to couple to an external pull-up resistor, a pull-down calibration terminal to couple to an external pull-down resistor, a voltage reference node, a first switch coupled between the pull-up calibration terminal and the voltage reference node, and a second switch coupled between the pull-down calibration terminal and the voltage reference node.
- a packaged integrated circuit to interface to memory with a first off-chip driver calibration terminal to couple to a first external resistor; a second off-chip driver calibration terminal to couple to a second external resistor; a first plurality of field effect transistors having sources coupled in parallel together to the first o f-chip driver calibration terminal and drains coupled in parallel together to a voltage reference node; and a second plurality of field effect transistors having drains coupled in parallel together to the second off-chip driver calibration terminal and sources coupled in parallel together to the voltage reference node.
- the computer system 100 includes a central processing unit (CPU) 101; input/output devices (I/O) 102 such as keyboard, modem, printer, external storage devices and the like; and monitoring devices (M) 103, such as a CRT or graphics display.
- the monitoring devices (M) 103 provide computer information in a human intelligible format such as visual or audio formats.
- the system 100 may be a number of different electronic systems other than a computer system.
- FIG. 2A a block diagram of a central processing unit 101A in which an embodiment of the invention may be utilized is illustrated.
- the central processing unit 101A includes a processor 201, a memory controller 202, and DDR memory 204A of a first memory channel coupled together as shown and illustrated.
- the central processing unit 101A may further include a second DDR memory 204B for a second memory channel, and a disk storage device 206.
- Each of the DDR memories 204A and 204B may be one or more memory modules (MMl-MMn) , such as a dual in-line memory module (DIMM) or a single in-line memory module (SIMM) .
- the one or more memory modules 250 may include one or more DDR memory chips 252 coupled to a printed circuit board 251 with an edge connection 254, such as a SIMM or DIMM.
- the one or more DDR memory chips 252 of the one or more memory modules 250 of the DDR memories 204A,204B are typically dynamic random access memory (DRAM) but may be other types of storage with a similar type of memory interface.
- DDR memory uses a switch point or trip point to distinguish between a high logic level (i.e., a one logic level) and a low logic level (i.e., a zero logic level) .
- the switch point or trip point is a single voltage level to distinguish between a one and a zero in contrast to a pair of voltage levels to distinguish between a one and a zero, such as used in standard TTL or CMOS logic for example.
- the waveform can swing over a narrower range of voltages and may transfer digital data (logical ones and zeroes) between devices at a faster data rate.
- the memory controller 202 is a DDR memory controller to provide a DDR memory interface to the DDR memory 204A and 204B.
- the disk storage device 206 may be a floppy disk, zip disk, DVD disk, hard disk, rewritable optical disk, flash memory or other non-volatile storage device.
- FIG. 2B a block diagram of a central processing unit 101B in which an embodiment of the invention may be utilized is illustrated.
- the central processing unit 101B includes a processor 201' with an internal memory controller 202' and DDR memory 204A of a first memory channel coupled together as shown and illustrated.
- the central processing unit 101B may further include a second DDR memory 204B for a second memory channel, and a disk storage device 206.
- the processor 201' has an internal DDR memory controller 202' to provide a DDR memory interface to the DDR memory 204A and 204B.
- the processor 201,201' may further include one or more execution units and one or more levels of cache memory. Other levels of cache memory may be external to the processor and interface to the memory controller.
- the processor, the one or more execution units, or the one or more levels of cache memory may read or write data (including instructions) through the memory controller with the DDR memory.
- data including instructions
- the processors 201,201' and the disk storage device 206 may both read and write information into the DDR memories 204A,204B.
- the output drivers in the memory devices 252 may be initially calibrated when first installed and then periodically calibrated thereafter, such as at power-on for example.
- OCD Off Chip Driver
- OCD calibration includes OCD pull-up calibration of the pull up transistors in the output drivers of the memory devices and OCD pull-down calibration of the pull down transistors in the output drivers of the memory devices .
- OCD calibration is used to adjust the strength of the output drivers in the memory devices, such as the output drivers in the memory devices 252 of the memory modules in the memory 204A,204B.
- data may be transmitted from the memory controller to the memory devices to adjust the drive settings of the output drivers from normal.
- the elements for OCD pull-up calibration in the memory controller 202,202' are utilized to calibrate the on resistance of the pull-up transistors in the output drivers of the memory device 252, illustrated as the resistor R ONPU 301 in Figure 3.
- the elements for OCD pull-down calibration In the memory controller 202,202' are utilized to calibrate the on resistance of the pull-down transistors in the output drivers of the memory device 252, illustrated as the resistor R ONPD 302 in Figure 3.
- the elements for OCD pull-up calibration by the memory controller 202,202' include the OCD high calibration pin OCDH 310 coupled to one end of an external pull-up resistor RE XT P U 311, an output of a tristate driver 314, and a first input of a comparator 318.
- the opposite end of the external pull-up resistor R E X TPU 311 is coupled to a first power supply terminal with a positive power supply voltage or VDDQ.
- the elements for OCD pull-up calibration further include a tristate driver 316 with an output coupled to a data output terminal/pin DQ1 312 and a second input of the comparator 318.
- the data output terminal/pin DQ1 312 may couple to the output driver of the memory device 252 being calibrated through an external stub resistor R S T DBI 351. In other cases, the external stub resistor R STUBI 351 may not be used.
- the tristate drivers 314 and 316 are enabled and receive logical zero level inputs to turn on the pull-down transistors to load the terminals/pins 310 and 312.
- the comparator 318 is used to compare the voltage levels on the OCD high calibration pin OCDH 310 and the data output terminal/pin DQ1 312 to determine whether or not an adjustment should be made in the drive strength of the pull-up transistor in the memory device 252. If an adjustment is desired, data may be transmitted from the memory controller to the memory device 252 to adjust the drive strength of the pull-up transistor in the memory device 252 from normal and then re-perform the comparison.
- the data may indicate an increase or decrease in one or more levels of incremental impedance or resistance for the pull-up of the output driver. This cycle may be repeated until a desired setting is reached.
- the elements for OCD pull-down calibration by the memory controller 202,202' include the OCD low calibration pin OCDL 320 coupled to one end of an external pull-down resistor R EXTPD 321, an output of a tristate driver 324, and a first Input of the comparator 328.
- the opposite end of the external pull-down resistor REXTPD 321 is coupled to a second power supply terminal having a negative power supply voltage or ground.
- the elements for OCD pull-down calibration further include a tristate driver 326 with an output coupled to a data output terminal/pin DQ2 322 and a second input of the comparator 328.
- the data output terminal/pin DQ2 322 may couple to the output driver of the memory device 252 being calibrated through an external stub resistor R STUB2 352. In other cases, the external stub resistor R STUB2 352 may not be used.
- the tristate drivers 324 and 326 are enabled and receive logical one level inputs to turn on the pull-up transistors to load the terminals/pins 320 and 322.
- the comparator 328 is used to compare the voltage levels on the OCD low calibration pin OCDL 320 and the data output terminal/pin DQ2 322 to determine whether or not an adjustment should be made in the drive strength of the pull-down transistor in the memory device 252. If an adjustment is desired, data may be transmitted from the memory controller to the memory device 252 to adjust the drive strength of the pull-down transistor in the memory device 252 from normal and then re-perform the comparison. The data may indicate an increase or decrease in one or more levels of incremental impedance or resistance for the pull-down of the output driver. This cycle may be repeated until a desired setting is reached.
- the external pull-up resistor R E X TPU 311 may have a resistance value equal to the sum of a pull-up target resistance and the resistance of the external stub resistor RSTUBI-
- the external pull-down resistor RE X T PD 321 may have a resistance value equal to the sum of a pull-down target resistance and the resistance of the external stub resistor R.STUB2 •
- the external stub resistor RSTUBI and the external stub resistor R STUB2 are external resistors to provide signal integrity.
- Each data bit DQi has an external stub resistor in the data path between the memory and the memory controller and each is typically of equal resistance.
- the pull-up target resistance and the pull-down target resistance are typically the same.
- the pull-up target resistance and the pull-down target resistance may be selected to be eighteen ohms plus or minus three ohms, in the range from 15 to 21 ohms of resistance.
- the OCD high calibration pin OCDH 310 and the OCD low calibration pin OCDL 320 are used for OCD calibration, they may also be used to generate an internal voltage reference (VREF) that is used by input receivers to detect logic levels in digital input signals. That is, the OCDH terminal/pin 310 and OCDL terminal/pin 320 are multifunctional by being used for OCD calibration and for internal voltage reference generation.
- VREF internal voltage reference
- the concept of generating an internal voltage reference (VREF) using the pair of calibration terminals/pins (OCDH 310 and OCDL 320) is illustrated.
- the internal voltage reference VREF is generated internally by the voltage divider resistor network established between VDDQ and VSS.
- the voltage divider resistor network uses two equal value resistances to divide the voltage between VDDQ and VSS in half.
- the pair of calibration terminals/pins (OCDH 310 and OCDL 320) are used to couple the calibration voltage generated thereon to an input of the OCD pull-up comparator 318 and the OCD pull-down comparator 328.
- the pair of calibration terminals/pins may be used for generating the internal voltage reference in order to receive data from the memory devices in the memory.
- a digital input receiver 400 has one input coupled to a data input terminal/pin DQi 414 and another input coupled to the internal voltage reference (VREF) .
- the digital input receiver 400 In response to the voltage level on the data input terminal/pin DQi 414 being above and below the voltage level of the internal voltage reference (VREF) , the digital input receiver 400 generates digital logic levels on its output DATA IN 416.
- the digital input receiver 400 may generate a high logic level (i.e., a one) on its output DATA IN 416. If the voltage level on the data input terminal/pin DQi 414 is below the voltage level of the internal voltage reference (VREF) , the digital input receiver 400 may generate a low logic level (i.e., a zero) on its output DATA IN 416. At least one pair of switches is used to switch the functionality of the calibration pins between the OCD calibration mode and the normal mode.
- Embodiments of the invention generate an internal voltage reference VREF by coupling the OCD Low and OCD High terminals/pins (also referred to herein as OCDL 320 and OCDH 310, respectively) together through the pair of switches when the memory controller is not in OCD calibration mode.
- the pair of switches may have some resistance associated with them when they are in a closed state.
- Figures 5A-5C illustrate the pair of switches 501,502 in the memory controller 202,202' being switched between the OCD calibration mode (i.e., pull-up and pull-down calibration) and the normal mode when data is to be received.
- the same node (VREF 500) can be used to distribute a pull-up calibration voltage, a pull-down calibration voltage, and the internal VREF for data reception. In this manner, the number of reference voltages distributed within a semiconductor device may be reduced with the appropriate voltage being selected thereon in response to the mode. Additionally, comparators 318 and 328 dedicated for performing calibration need not be used. Comparators in each input receiver 400A-400n may be used to perform calibration during calibration mode, in addition to receiving data during normal mode.
- Each of switches 501, 502 has a first switch connection, a second switch connection, and a control connection. The control connection controls the opening and closing of the switch between the first switch connection and the second switch connection.
- Switch 501 is coupled between the pull-up calibration terminal OCDH 310 and the voltage reference node 500.
- the first switch connection of switch 501 is coupled to the pull-up calibration terminal OCDH 310 and second switch connection of switch 501 is coupled to the voltage reference node 500.
- the control connection of switch 501 is coupled to the switch controller 510.
- Switch 502 is coupled between the pull-down calibration terminal OCDL 320 and the voltage reference node 500.
- the first switch connection of switch 502 is coupled to the pull-down calibration terminal OCDL 320 and second switch connection of switch 502 is coupled to the voltage reference node 500.
- the control connection of switch 502 is coupled to the switch controller 510.
- the switches are set to provide OCD pull- up calibration.
- Switch 501 is closed and switch 502 is open in response to receiving switch control signals from the switch controller 510.
- the switch controller 510 is responsive to the mode. In this case, the switch controller 510 generates the switch control signals in response to being in an OCD calibration mode to perform OCD pull-up calibration.
- switch 501 may represent a plurality of switches in parallel with at least one being selectively closed.
- Switch 502 may represent a plurality of switches in parallel with none being closed in Figure 5A.
- the tristate driver 314 is enabled with a logical zero input to couple a pull-down load onto the OCDH terminal/pin 310.
- the external resistor REXT P U 311 is coupled between VDDQ and the OCDH terminal/pin 310 to generate a calibration voltage thereon.
- the calibration voltage on the OCDH terminal/pin 310 is substantially coupled onto the node VREF 500 through the switch 501 as little current flows through it.
- the calibration voltage on the OCDH terminal/pin 310 and the node VREF 500 is used by a comparator of the input receivers 400A-400n to compare with a voltage level on a respective data terminal/pin DQi of a data bus, such as described previously with the data terminal/pin DQI 312.
- the data bus of data terminals/pins DQi may be a unidirectional or a bidirectional data bus. In the case of a unidirectional data bus, the data terminals/pins DQi are data input terminals/pins to the memory controller.
- the data terminals/pins DQi are data input/output terminals/pins of the memory controller and have on-chip input receivers and output drivers coupled thereto.
- the off chip output drivers that are to be calibrated and from which data is to be received, have their outputs coupled to the respective data terminals/pins DQi.
- the switches are set to provide OCD pulldown calibration.
- Switch 501 is open and switch 502 is closed in response to receiving switch control signals from the switch controller 510.
- the switch controller 510 generates the switch control signals in response to being in an OCD calibration mode to perform OCD pull-down calibration.
- switch 501 may represent a plurality of switches in parallel with none closed.
- Switch 502 may represent a plurality of switches in parallel with at least one being selectively closed in Figure 5B.
- the tristate driver 324 is enabled with a logical one input to couple a pull-up load onto the OCDL terminal/pin 320.
- the external resistor RE XTPD 321 is coupled between ground and the OCDL terminal/pin 320 to generate a calibration voltage thereon.
- the calibration voltage on the OCDL terminal/pin 320 is substantially coupled onto the node VREF 50O through the switch 502 as little current flows through it.
- the calibration voltage on the OCDL terminal/pin 320 and the node VREF 500 is used by a comparator of the input receivers 400A-400n to compare with a voltage level on a data terminal/pin DQi, such as described previously with the data terminal/pin DQ2 322. In this manner, each data terminal/pin DQi may have the pull-up and the pull-down in each off chip driver of the memory device calibrated.
- the switches are set to provide the internal VREF for data reception.
- Switch 501 is closed and switch 502 is closed in response to receiving switch control signals from the switch controller 510.
- the switch controller 510 generates the switch control signals in response to being in a normal to receive data in from the memories when not driving data out over the data bus.
- switch 501 may represent a plurality of switches in parallel with at least one being selectively closed.
- Switch 502 may represent a plurality of switches in parallel with at least one being selectively closed.
- the tristate drivers 314 and 324 are disabled, (i.e., tristated) so that neither drives a load onto the OCDH terminal/pin 310 or the OCDL terminal/pin 320 and therefore they are not illustrated.
- the external resistor REXTP D 321 remains coupled between ground and the OCDL terminal/pin 320 and the external resistor R EXTPU 311 remains coupled between VDDQ and the OCDH terminal/pin 310.
- the resistance of the external resistor R EXTPU 311, the switch resistance of switch 501, the switch resistance of switch 502, and the resistance of the external resistor REXTPD 321, divide up the voltage between VDDQ and ground and couple it to node VREF 500.
- the switch point of the input receivers is the midpoint between VDDQ and ground. In this case, it is desirable to set the resistance between VDDQ and VREF 500 equal to the resistance between VREF 500 and ground in order to divide the voltage between VDDQ and ground in half on VREF 500.
- the switch resistances of the switches 501 and 502 are adjusted to be equivalent to divide the voltage between VDDQ and ground in half on VREF 500.
- the switch point may be offset from the midpoint between VDDQ and ground by using different switch resistances for the switches 501 and 502.
- the internal voltage reference on the node VREF 500 is coupled into one input of the digital input receivers 400.
- the internal voltage reference on the node VREF 500 is used by the digital input receivers 400 to compare with a voltage level on a data terminal/pin, such as DQi 414, to generate data in 416 as described and illustrated with reference to Figure 4.
- a first plurality of field effect transistors (“FETs”) with sources connected in parallel together and drains connected in parallel together between OCDH and VREF and a second plurality of field effect transistors (“FETs”) with sources connected in parallel together and drains connected in parallel together between VREF and OCDL may be used to generate a selectable voltage level of VREF.
- FETs field effect transistors
- a second plurality of field effect transistors with sources connected in parallel together and drains connected in parallel together between VREF and OCDL may be used to generate a selectable voltage level of VREF.
- the number of transistors switched on and off can be varied to substantially achieve the midpoint voltage level.
- the PFETs may be used to generate the internal voltage reference VREF.
- n-channel field effect transistors (“NFETs") may replace one or both sets of the PFETs.
- the PFETs may be complemented with NFETs with sources and drains coupled in parallel with those of the PFETs and gates controlled so they are turned on in parallel together.
- a different kind of transistor switch or a different type of switch may replace the PFETs.
- a first plurality of PFETs 601A-601m have their sources connected in parallel together and their drains connected in parallel together between the OCD high calibration terminal/pin OCDH 310 and VREF 500.
- a second plurality of PFETs 602A-602m have their sources connected in parallel together and their drains connected in parallel together between VREF 500 and the OCD low calibration terminal/pin OCDL 320.
- the widths and lengths of the first plurality of PFETs 601A-601m may vary from one to another to provide varying switch resistances when closed.
- the widths and lengths of the second plurality of PFETs 602A-602m may also vary from one to another to provide varying switch resistances when closed.
- the PFETs 601A-601m and the PFETs 602A-602m may then be used to generate a selectable voltage level of VREF 500 by selectively controlling the number of transistors turned on in parallel and by controlling the voltage level of the control signals 610A-610m and 611A-611m driving their gates.
- the resistance between the OCD high calibration terminal/pin OCDH 310 and VREF 500 may be set equivalent to the resistance between VREF 500 and the OCD low calibration terminal/pin OCDL 320 to provide voltage division by one half.
- the switch controller 510 is responsive to a mode input 650 in generation of the switch control signals PDO-PDm 610A-610m and the switch control signals PUO-PUm 611A-611m.
- the mode input 650 is normal, the internal voltage reference is generated on node VREF 500 by at least one pair of switches, one PFET of PFETs 601A-601m is turned on and one PFET of PFETs 602A-602m is turned on. If the mode input 650 is OCD pull-up calibration, the pull-up calibration voltage is coupled into the node VREF 500 and at least one or more PFETs of the PFETs 601A-601m is turned on and none of PFETs 602A-602m is turned on (i.e. PFETs 602A-602m are all off) .
- the pull-down calibration voltage is coupled into the node VREF 500 and at least one or more PFETs of the PFETs 602A-602m is turned on and none of PFETs 601A-601m is turned on (i.e. PFETs 60lA-601m are all off) .
- VREF 500 is fanned out and coupled into an input of each digital input receiver 400A-400n.
- the data terminals/pins DQl-DQn 614A-614n are respectively coupled into the other input of each digital input receiver 400A- 400n.
- the calibration voltages selectively coupled from the OCDH terminal/pin 310 and the OCDL terminal/pin 320 onto the node VREF 500 are used by a comparator of the input receivers 400A-400n to compare with a voltage level on the data terminals/pins DQl-DQn 614A- 614n.
- the data bus of data terminals/pins DQl-DQn 614A-614n may be a unidirectional or a bidirectional data bus. In the case of a unidirectional data bus, the data terminals/pins DQl-DQn 614A-614n are data input terminals/pins.
- the data terminals/pins DQl-DQn 614A-614n are data input/output terminals/pins of the memory controller and have on-chip input receivers and output drivers coupled thereto.
- the off chip output drivers that are to be calibrated and from which data is to be received, have their outputs coupled to the respective data terminals/pins DQl-DQn 614A-614n.
- Each data terminal/pin DQl-DQn 614A-614n may have the pull-up and the pull-down in each off chip driver of the memory device calibrated.
- the reference voltage selectively coupled onto the node VREF 500 is used by a comparator of the input receivers 400A-400n to compare with a voltage level on the data terminals/pins DQ1- DQn 614A-614n to determine the logical state of incoming signals .
- a comparator of the input receivers 400A-400n it is desirable to generate VREF at the normal mid-point between power supply rails VDDQ and ground.
- the number of transistor switched on and off can be varied by the switch controller 510 to substantially achieve the midpoint voltage level. However in some cases it may be desirable to set the voltage level of VREF offset from the midpoint value, such as for testing or experimentation, for example.
- an equal strength of FETs When operated in normal mode, an equal strength of FETs may be connected to OCD Low and OCD High pins . Even though the on—resistance of the FETS may vary with process, voltage, and temperature; it is possible to match the FETs so that the resistance from VREF 500 to the OCDH terminal/pin 310 is equal to the resistance from VREF 500 to the OCDL terminal/pin 320 to get an accurate mid-point VREF.
- the switch controller 510 may also generate various voltage levels of the switch control signals PDO-PDm 610A-610m and the switch control signals PUO-PUm 611A-611m to vary gate voltage applied to the gates of the PFETs 601A-601m and the PFETs 602A-602m in order to vary their resistance so that they may be more equivalent or less equivalent as desired.
- the voltage level on node VREF 500 is respectively set for calibration as discussed previously.
- the current through the field effect transistor (“FET”) switches is substantially close to zero such that the voltage drop across them is negligible.
- FET field effect transistor
- the packaged integrated circuit 700 may be a memory controller 202, a processor 201' including a memory controller 202', or another device with a DDR memory interface.
- the packaged integrated circuit 700 includes a semiconductor die 701 and a package 702.
- the package 702 includes an OCDH terminal/pin 704 and an OCDL terminal/pin 706 and no external VREF terminal/pin.
- the OCDH terminal/pin 704 and the OCDL terminal/pin 706 may be pins or other types of terminals of different semiconductor packages, such as solder bumps, solder balls, or the various types of leaded terminals (e.g., straight-lead, bent-lead, j-lead, gull-lead, and 1-lead) and leadless terminals used in semiconductor packages.
- the OCDH terminal/pin 704 and an OCDL terminal/pin 706 selectively provide multiple functions - OCD calibration and internal VREF generation.
- the semiconductor die 701 includes an OCDH pad 707 and an OCDL pad 709 with no extra VREF pad to connect to an external VREF terminal/pin.
- the embodiments of the invention may reduce the number of printed circuit board components (e.g., no external resistors for voltage divider) and the number of pins in the pin-out (or balls in a ball-out of a ball grid array package) of memory controllers.
- the embodiments of the invention can internally generate a voltage reference, eliminating the external VREF pin/terminal, without a loss of accuracy or the use of complex analog circuits . While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those ordinarily skilled in the art. For example, while a DDR memory interface has been described in detail within a DDR memory controller, it is possible to implement embodiments of the invention in other types of chips having a similar type of interface.
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE602004011809T DE602004011809T2 (en) | 2003-11-14 | 2004-11-05 | INTERNAL VOLTAGE DIFFERENCE FOR A MEMORY INTERFACE |
EP04810345A EP1683156B1 (en) | 2003-11-14 | 2004-11-05 | Internal voltage reference for memory interface |
JP2006539652A JP4422153B2 (en) | 2003-11-14 | 2004-11-05 | Integrated circuit, method, system, processor, package integrated circuit for connection with memory |
CN2004800405040A CN1906696B (en) | 2003-11-14 | 2004-11-05 | Integrated circuit, system and emthod for memory interface |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/714,075 US7095245B2 (en) | 2003-11-14 | 2003-11-14 | Internal voltage reference for memory interface |
US10/714,075 | 2003-11-14 |
Publications (1)
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WO2005050656A1 true WO2005050656A1 (en) | 2005-06-02 |
Family
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PCT/US2004/036825 WO2005050656A1 (en) | 2003-11-14 | 2004-11-05 | Internal voltage reference for memory interface |
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US (1) | US7095245B2 (en) |
EP (1) | EP1683156B1 (en) |
JP (1) | JP4422153B2 (en) |
CN (1) | CN1906696B (en) |
AT (1) | ATE386326T1 (en) |
DE (1) | DE602004011809T2 (en) |
TW (1) | TWI294217B (en) |
WO (1) | WO2005050656A1 (en) |
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CN105321577B (en) * | 2015-11-26 | 2018-09-14 | 上海兆芯集成电路有限公司 | Data receiver chip |
CN105469817B (en) * | 2015-11-26 | 2018-06-12 | 上海兆芯集成电路有限公司 | Data receiver chip |
CN105489235B (en) * | 2015-11-26 | 2019-04-09 | 上海兆芯集成电路有限公司 | Data receiver chip |
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CN107315442B (en) * | 2017-06-30 | 2019-04-30 | 上海兆芯集成电路有限公司 | Controller and reference voltage generating method |
KR20190099933A (en) * | 2018-02-20 | 2019-08-28 | 삼성전자주식회사 | Memory Device determining operation mode based on external voltage and Operating Method thereof |
CN110597529A (en) * | 2019-09-29 | 2019-12-20 | 上海菱沃铂智能技术有限公司 | Burner and burning method for parameter calibration of microcontroller |
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- 2004-11-05 JP JP2006539652A patent/JP4422153B2/en not_active Expired - Fee Related
- 2004-11-05 CN CN2004800405040A patent/CN1906696B/en not_active Expired - Fee Related
- 2004-11-05 EP EP04810345A patent/EP1683156B1/en not_active Not-in-force
- 2004-11-05 WO PCT/US2004/036825 patent/WO2005050656A1/en active IP Right Grant
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Also Published As
Publication number | Publication date |
---|---|
CN1906696A (en) | 2007-01-31 |
EP1683156A1 (en) | 2006-07-26 |
US20050104624A1 (en) | 2005-05-19 |
US7095245B2 (en) | 2006-08-22 |
JP4422153B2 (en) | 2010-02-24 |
ATE386326T1 (en) | 2008-03-15 |
DE602004011809T2 (en) | 2009-02-05 |
DE602004011809D1 (en) | 2008-03-27 |
TWI294217B (en) | 2008-03-01 |
TW200529559A (en) | 2005-09-01 |
CN1906696B (en) | 2010-05-05 |
JP2007520839A (en) | 2007-07-26 |
EP1683156B1 (en) | 2008-02-13 |
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