CA1199069A - Active voltage probe - Google Patents
Active voltage probeInfo
- Publication number
- CA1199069A CA1199069A CA000399660A CA399660A CA1199069A CA 1199069 A CA1199069 A CA 1199069A CA 000399660 A CA000399660 A CA 000399660A CA 399660 A CA399660 A CA 399660A CA 1199069 A CA1199069 A CA 1199069A
- Authority
- CA
- Canada
- Prior art keywords
- coaxial cable
- voltage
- input
- active voltage
- follower
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R13/00—Arrangements for displaying electric variables or waveforms
- G01R13/20—Cathode-ray oscilloscopes
- G01R13/22—Circuits therefor
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/145—Indicating the presence of current or voltage
- G01R19/155—Indicating the presence of voltage
Abstract
Abstract An active voltage probe receiving a DC power voltage via an outer conductor of a coaxial cable is disclosed. The probe includes a differential amplifier with inputs connected to input and reference terminals via DC paths and a follower amplifier with an input connected to the input terminal via an AC path. Out-puts currents from the differential and follower ampli-fiers are applied to an inner conductor of the coaxial cable.
Description
6~
ACTIVE VOLTAGE PROBE
Background of the Invention The present invention relates to an active volt-age probe for an electronic measurement instrument.
Active voltage probes provide a better method of coupling high speed signals to an electronic measure-ment instrument, such as an oscilloscope or a logic analyzer, than passive probes can provide. The active voltage probe has higher input impedance with less attenuation than a passive voltage probe. Its use extends the measurement capabilities of the probe-instrument combination. There are two types of active voltage probes: (1) a cathode follower probe and ~2) a source follower probe, with the source follower ver-sion being more popular.
Conventional active voltage probes have three basic parts; a probe head, a cable and termination box. The probe head includes a source follower ampli-fier to receive a signal from a probe tip, and an output from the source follower is transmitted to an output amplifier of the termination box through the cable. Since the active devices of the probe head receive power from the termination box throuyh an additional conductor in the cable, the conventional active probe is bulky in construction. Moreover, both signal and power voltage connectors are needed on a panel of the measurement instrument. When many probes are necessary to simultaneously measure a plurality of parameters of components such as integrated circuits, it is difficult to connect the required probes to the test points or component leads in a compact area, and hence more panel area of the instrument is necessary for the power voltage connectors. In addition, prior art probes are not isolated from instrument ground and therefore cannot measure a voltage (floating voltage) with respect to no zero reference voltage.
)65~
Summar~ of the Invention _ ___ _ _____ _ _ In accordance with an aspect of the invention there is provided an active voltage probe, comprising a probe head including a differential amplifier with inputs connected to input and reference terminals through DC paths, and follower amplifier means with an input connected to said input terminal through an AC path; a coaxial cable including an inner conductor for transmitting output currents from said differential amplifier and said follower amplifier means, and an outer conductor for applying a DC power voltage to said differential amplifier and said follower amplifier means; and an output circuit connected to the opposite end of said coaxial cable, wherein said outer conductor is connected to a DC power voltage source and said inner conductor is connected to a lS termination resistor.
According to the present invention, an active circuit of a probe head is a floating-voltage circuit which receives a power voltage through an outer conductor, for example, a shield member of coaxial cable. At a termin-ation box or a measurement instrument, an offset voltageis applied to a signal path or an inner conductor of the coaxial cable for compensating a reference voltage. The probe head includes a differential amplifier with non-inverting and inverting inputs connected to input (probe tip) and reference terminals through DC paths for DC and low frequency co~ponents of an input signal to be measured, and a follower amplifier connected to the input terminal through an AC path for middle and high frequency components of the input signal. Outputs from the differential and follower amplifiers are mixed and applied to the inner conductor of the coaxial cable. The follower amplifier is a source follower or a combination of the source follower and an emitter follower.
It is therefore one object of the present invention to provide an active voltage probe which does not need an 95~
-2a-additional power conductor for an active circuit in a probe head.
It is another object to provide an active voltaye probe which can detect signal from both of grounded and floating-voltage circuits.
It is a further object to provide an active voltage probe allowing significant reductions in assembly cost and physical size.
It is an additional object to provide an active voltage probe which does not require a complex circuit and an additional connector to a termination box or a measurement instrument.
This invention is pointed out with particularity in the appended claims. A more thorough understanding of the above and further objects and advantages of 9~
this invention may be obtained by referring to the following description taken in conj~mction with the accompanying drawings.
Drawing A single drawing shows an active voltage probe of one preferred embodiment according to this invention.
Detailed Description of the Invention Referring to the drawing, there is shown a cir-cuit schematic of one embodiment according to this invention. An active voltage probe comprises probe head 10, coaxial cable 12, and output circuit 14 which may be in a termination box or a measurement i~stru-ment. Probe head lO includes differential or opera-tional amplifier 16 and source and emitter follower amlifiers 18. A non-inverting input of operational amplifier 16 is connected to input terminal 20 through large resistor 22 and small resistor 24, and an invert-ing input thereof is connected to reference terminal 26 through large resistor 28. An output of amplifier 16 is connected through large resistor 30 to a gate of field effect transistor (FET) 32 which is connected to the common junction of resistors 22 and 24 through small resistor 34, large resistor 36, and capacitors 38 and 40. A drain of FET 23 and a collector of NPN
transistor 42 are connected to an outer conductor of coaxial cable 12. Resistor 44 is inserted betwen a source of FET 32 and a base of transistor 42 which is -30 connected through resistor 46 and capacitor 48 to the common junction of resistor 34 and capacitor 38 and further connected through resistors 50 and 52 to an inner conductor of coaxial cable 12. Resistor 54 is inserted between an emitter of transistor 42 and the 35 common junction of resistors 50 and 52. Capacitor 56 is inserted between the outer conductor of coaxial cable 12 and reference terminal 26, and a series circuit consisting of resistors 58, 50 and 62 is connected between the outer and inner conductors of :1~99~
coaxial cable 12 wherein the common junction of resis-tors 58 and 60 is connected to the common junction of resistors 52 and S~t` through Zener diode 64, and the common junction of r~sistors 60 and 62 is connected to the non-inverting input of operational amplifier 16.
Positive and negative power voltage terminals of opera-tional amlifier 16 are connected to the outer connec-tor of coaxial cable 12 through resistor 66 and the common junction of resistors 50 and 52, respectfully.
Resistor 68 is inserted between the inverting input and negative power voltage terminal of operational amplifier 16. The circuit in probe head 10 can be implemented as a hybrid.
In output circuit 14, the outer conductor of coaxial cable 12 is connected to voltage source Vl, and the inner conductor thereof is connected to volt-age source V2 through termination resistor 70 and further connected to a non-inverting input end of comparator 72. Voltage Vl is higher than voltage V2.
It should be noted that this embodiment is used in a logic analyzer. An inverting input receives a thres-hold level from terminal 74 through resistor 76. A
series circuit consisting of resistor 78, potentiom-eter 80 and resistor 82 is inserted between the non-inverting and inverting inputs of comparator 72, and acenter tap of potentiometer 80 receives voltage V3. A
push-pull output of comparator 72 is applied to termi-nals 84 and 86.
Input terminal 20 detects a signal to be measured from a test point of a PUT ~product under test), and reference terminal 26 is connected to a reference potential of the PUT. Operational amplifier 16, FET 32 and transistor 42 receive their operation voltages from voltage source Vl through the outer conductor of coaxial cable 12. Since voltage V1 is the DC voltage, there is no problem with regard to the outer conductor acting as the shield. At middle and high frequency components of the input signal, reference input termi-nal 26 acts as AC ground, and these frequency com-ponents pass through resistor 24 and capacitor 40. The high frequency component of the input signal is divid-ed by capacitors 38 48 and floating and inter-elec-trode capacitances at the gate of FET 32 and the base of transistor 42. The divided high frequency component t is amplified by FET 32 and transistor 42 respectively functioning as source and emitter follower amlifiers, and the output currents therefrom are applied to the inner conductor of coaxial cable 12 through resistor 52.
The middle frequency component of the input sig-nal is divided by capacitors 38-40, floating and in-ter-electrode capacitances at the gate of FET 32 and the base of transistor 42, and resistors 30-36. The di~ided middle frequency component is a~plified by source follower/emitter follower amplifiers 18, and the output currents therefrom are applied to the inner conductor of coaxial cable 12.
~he DC and low frequency components of the input signal are applied to the non-inverting input of opera-tional amplifier 16 through input terminal 20 and resistor 24-22, and a different voltage between the reference potential at terminal 26 and the DC and low frequency components is obtained at the output of amplifier 16. It should be noted that a general opera-tional amplifier is for DC and low frequency signals and is not proper for middle and high frequency sig-nals. The output from operational amplifier 16 is applied to the inner conductor of coaxial cable 12 through resistor 30 and source follower/emitter fol lower amplifiers 18. The signal at the common junction of resistors 50 and 54 is fed back to the inverting irput of operational amplifier 16 through feedback resistor 68. The DC bias and lo~ frequency gain is set by operational amplifier 16, resistors 22-28-52-60-62-68 and Zener diode 64. This Zener diode is present in order to provide the current offset required to bias the probe. Terminals 20 and 26 can be cor~ected to the floating circuit because of differ-ential amplifier 16. Since the negative voltage termi-nal of amplifier 16 is connected to the common junc-tion of resistors ~O and 52, amplifier 16 is floated, and the operation characteristic thereof is improved.
T~e high, middle and low frequency gains and the DC gain are set to be equal. When the difference voltage (V20 - V26) between terminals 20 and 26 is zero, outp~t current I t flowing through resistor 52 and the inner conductor of coaxial cable 12 is the bias current Io determined by Zener diode 64 and other components. When the difference voltage between termi-nals 20 and 26 is V (positive or negative), output current IoUt is Io ~ (V/Ro), wherein Ro is determined by the gains of the amplifiers in probe head 10.
Output current flows to resistor 70, and a voltage across resistor 70 is R70 [lo ~ (V~Ro)3, wherein R70 is the resistance of resistor 70. Since resistor 70 receives voltage V2 the voltage generated by R70 Io is cancelled, and only the signal component voltage between terminals 20 and 26 is applied to the non-inverting input of comparator 72. Resistors 78-80-82 comprise a DC balance circuit. In this embodiment, the measurement instrument is a logic analyzer, and com-parator 72 compares the corresponding input voltage with the threshold voltage from terminal 74. The push-pull output signal at terminals 84 and 86 is applied to a main circuit of the logic analyzer. If the measurement instrument is an oscilloscope, the common junction of resistor 70 and the inner conductor of coaxial cable 12 may be connected to a buffer ampli-fier. A conventional coaxial connector can be used for the connection between coaxial cable 12 and output circuit 14.
While I have shown and described herein the pre-ferred embodiment of my invention, it will be apparent to those skilled in the art that many changes and modifications may be made without departing from my invention in its broader aspects.
ACTIVE VOLTAGE PROBE
Background of the Invention The present invention relates to an active volt-age probe for an electronic measurement instrument.
Active voltage probes provide a better method of coupling high speed signals to an electronic measure-ment instrument, such as an oscilloscope or a logic analyzer, than passive probes can provide. The active voltage probe has higher input impedance with less attenuation than a passive voltage probe. Its use extends the measurement capabilities of the probe-instrument combination. There are two types of active voltage probes: (1) a cathode follower probe and ~2) a source follower probe, with the source follower ver-sion being more popular.
Conventional active voltage probes have three basic parts; a probe head, a cable and termination box. The probe head includes a source follower ampli-fier to receive a signal from a probe tip, and an output from the source follower is transmitted to an output amplifier of the termination box through the cable. Since the active devices of the probe head receive power from the termination box throuyh an additional conductor in the cable, the conventional active probe is bulky in construction. Moreover, both signal and power voltage connectors are needed on a panel of the measurement instrument. When many probes are necessary to simultaneously measure a plurality of parameters of components such as integrated circuits, it is difficult to connect the required probes to the test points or component leads in a compact area, and hence more panel area of the instrument is necessary for the power voltage connectors. In addition, prior art probes are not isolated from instrument ground and therefore cannot measure a voltage (floating voltage) with respect to no zero reference voltage.
)65~
Summar~ of the Invention _ ___ _ _____ _ _ In accordance with an aspect of the invention there is provided an active voltage probe, comprising a probe head including a differential amplifier with inputs connected to input and reference terminals through DC paths, and follower amplifier means with an input connected to said input terminal through an AC path; a coaxial cable including an inner conductor for transmitting output currents from said differential amplifier and said follower amplifier means, and an outer conductor for applying a DC power voltage to said differential amplifier and said follower amplifier means; and an output circuit connected to the opposite end of said coaxial cable, wherein said outer conductor is connected to a DC power voltage source and said inner conductor is connected to a lS termination resistor.
According to the present invention, an active circuit of a probe head is a floating-voltage circuit which receives a power voltage through an outer conductor, for example, a shield member of coaxial cable. At a termin-ation box or a measurement instrument, an offset voltageis applied to a signal path or an inner conductor of the coaxial cable for compensating a reference voltage. The probe head includes a differential amplifier with non-inverting and inverting inputs connected to input (probe tip) and reference terminals through DC paths for DC and low frequency co~ponents of an input signal to be measured, and a follower amplifier connected to the input terminal through an AC path for middle and high frequency components of the input signal. Outputs from the differential and follower amplifiers are mixed and applied to the inner conductor of the coaxial cable. The follower amplifier is a source follower or a combination of the source follower and an emitter follower.
It is therefore one object of the present invention to provide an active voltage probe which does not need an 95~
-2a-additional power conductor for an active circuit in a probe head.
It is another object to provide an active voltaye probe which can detect signal from both of grounded and floating-voltage circuits.
It is a further object to provide an active voltage probe allowing significant reductions in assembly cost and physical size.
It is an additional object to provide an active voltage probe which does not require a complex circuit and an additional connector to a termination box or a measurement instrument.
This invention is pointed out with particularity in the appended claims. A more thorough understanding of the above and further objects and advantages of 9~
this invention may be obtained by referring to the following description taken in conj~mction with the accompanying drawings.
Drawing A single drawing shows an active voltage probe of one preferred embodiment according to this invention.
Detailed Description of the Invention Referring to the drawing, there is shown a cir-cuit schematic of one embodiment according to this invention. An active voltage probe comprises probe head 10, coaxial cable 12, and output circuit 14 which may be in a termination box or a measurement i~stru-ment. Probe head lO includes differential or opera-tional amplifier 16 and source and emitter follower amlifiers 18. A non-inverting input of operational amplifier 16 is connected to input terminal 20 through large resistor 22 and small resistor 24, and an invert-ing input thereof is connected to reference terminal 26 through large resistor 28. An output of amplifier 16 is connected through large resistor 30 to a gate of field effect transistor (FET) 32 which is connected to the common junction of resistors 22 and 24 through small resistor 34, large resistor 36, and capacitors 38 and 40. A drain of FET 23 and a collector of NPN
transistor 42 are connected to an outer conductor of coaxial cable 12. Resistor 44 is inserted betwen a source of FET 32 and a base of transistor 42 which is -30 connected through resistor 46 and capacitor 48 to the common junction of resistor 34 and capacitor 38 and further connected through resistors 50 and 52 to an inner conductor of coaxial cable 12. Resistor 54 is inserted between an emitter of transistor 42 and the 35 common junction of resistors 50 and 52. Capacitor 56 is inserted between the outer conductor of coaxial cable 12 and reference terminal 26, and a series circuit consisting of resistors 58, 50 and 62 is connected between the outer and inner conductors of :1~99~
coaxial cable 12 wherein the common junction of resis-tors 58 and 60 is connected to the common junction of resistors 52 and S~t` through Zener diode 64, and the common junction of r~sistors 60 and 62 is connected to the non-inverting input of operational amplifier 16.
Positive and negative power voltage terminals of opera-tional amlifier 16 are connected to the outer connec-tor of coaxial cable 12 through resistor 66 and the common junction of resistors 50 and 52, respectfully.
Resistor 68 is inserted between the inverting input and negative power voltage terminal of operational amplifier 16. The circuit in probe head 10 can be implemented as a hybrid.
In output circuit 14, the outer conductor of coaxial cable 12 is connected to voltage source Vl, and the inner conductor thereof is connected to volt-age source V2 through termination resistor 70 and further connected to a non-inverting input end of comparator 72. Voltage Vl is higher than voltage V2.
It should be noted that this embodiment is used in a logic analyzer. An inverting input receives a thres-hold level from terminal 74 through resistor 76. A
series circuit consisting of resistor 78, potentiom-eter 80 and resistor 82 is inserted between the non-inverting and inverting inputs of comparator 72, and acenter tap of potentiometer 80 receives voltage V3. A
push-pull output of comparator 72 is applied to termi-nals 84 and 86.
Input terminal 20 detects a signal to be measured from a test point of a PUT ~product under test), and reference terminal 26 is connected to a reference potential of the PUT. Operational amplifier 16, FET 32 and transistor 42 receive their operation voltages from voltage source Vl through the outer conductor of coaxial cable 12. Since voltage V1 is the DC voltage, there is no problem with regard to the outer conductor acting as the shield. At middle and high frequency components of the input signal, reference input termi-nal 26 acts as AC ground, and these frequency com-ponents pass through resistor 24 and capacitor 40. The high frequency component of the input signal is divid-ed by capacitors 38 48 and floating and inter-elec-trode capacitances at the gate of FET 32 and the base of transistor 42. The divided high frequency component t is amplified by FET 32 and transistor 42 respectively functioning as source and emitter follower amlifiers, and the output currents therefrom are applied to the inner conductor of coaxial cable 12 through resistor 52.
The middle frequency component of the input sig-nal is divided by capacitors 38-40, floating and in-ter-electrode capacitances at the gate of FET 32 and the base of transistor 42, and resistors 30-36. The di~ided middle frequency component is a~plified by source follower/emitter follower amplifiers 18, and the output currents therefrom are applied to the inner conductor of coaxial cable 12.
~he DC and low frequency components of the input signal are applied to the non-inverting input of opera-tional amplifier 16 through input terminal 20 and resistor 24-22, and a different voltage between the reference potential at terminal 26 and the DC and low frequency components is obtained at the output of amplifier 16. It should be noted that a general opera-tional amplifier is for DC and low frequency signals and is not proper for middle and high frequency sig-nals. The output from operational amplifier 16 is applied to the inner conductor of coaxial cable 12 through resistor 30 and source follower/emitter fol lower amplifiers 18. The signal at the common junction of resistors 50 and 54 is fed back to the inverting irput of operational amplifier 16 through feedback resistor 68. The DC bias and lo~ frequency gain is set by operational amplifier 16, resistors 22-28-52-60-62-68 and Zener diode 64. This Zener diode is present in order to provide the current offset required to bias the probe. Terminals 20 and 26 can be cor~ected to the floating circuit because of differ-ential amplifier 16. Since the negative voltage termi-nal of amplifier 16 is connected to the common junc-tion of resistors ~O and 52, amplifier 16 is floated, and the operation characteristic thereof is improved.
T~e high, middle and low frequency gains and the DC gain are set to be equal. When the difference voltage (V20 - V26) between terminals 20 and 26 is zero, outp~t current I t flowing through resistor 52 and the inner conductor of coaxial cable 12 is the bias current Io determined by Zener diode 64 and other components. When the difference voltage between termi-nals 20 and 26 is V (positive or negative), output current IoUt is Io ~ (V/Ro), wherein Ro is determined by the gains of the amplifiers in probe head 10.
Output current flows to resistor 70, and a voltage across resistor 70 is R70 [lo ~ (V~Ro)3, wherein R70 is the resistance of resistor 70. Since resistor 70 receives voltage V2 the voltage generated by R70 Io is cancelled, and only the signal component voltage between terminals 20 and 26 is applied to the non-inverting input of comparator 72. Resistors 78-80-82 comprise a DC balance circuit. In this embodiment, the measurement instrument is a logic analyzer, and com-parator 72 compares the corresponding input voltage with the threshold voltage from terminal 74. The push-pull output signal at terminals 84 and 86 is applied to a main circuit of the logic analyzer. If the measurement instrument is an oscilloscope, the common junction of resistor 70 and the inner conductor of coaxial cable 12 may be connected to a buffer ampli-fier. A conventional coaxial connector can be used for the connection between coaxial cable 12 and output circuit 14.
While I have shown and described herein the pre-ferred embodiment of my invention, it will be apparent to those skilled in the art that many changes and modifications may be made without departing from my invention in its broader aspects.
Claims (7)
1. An active voltage probe, comprising:
a probe head including a differential amplifier with inputs connected to input and reference terminals through DC paths, and follower amplifier means with an input connected to said input terminal through an AC path;
a coaxial cable including an inner conductor for transmitting output currents from said differential amplifier and said follower amplifier means, and an outer conductor for applying a DC power voltage to said differential amplifier and said follower amplifier means;
and an output circuit connected to the opposite end of said coaxial cable, wherein said outer conductor is connected to a DC power voltage source and said inner conductor is connected to a termination resistor.
a probe head including a differential amplifier with inputs connected to input and reference terminals through DC paths, and follower amplifier means with an input connected to said input terminal through an AC path;
a coaxial cable including an inner conductor for transmitting output currents from said differential amplifier and said follower amplifier means, and an outer conductor for applying a DC power voltage to said differential amplifier and said follower amplifier means;
and an output circuit connected to the opposite end of said coaxial cable, wherein said outer conductor is connected to a DC power voltage source and said inner conductor is connected to a termination resistor.
2. An active voltage probe according to claim 1 wherein the output from said differential amplifier is applied to the input end of said follower amplifier means.
3. An active voltage probe according to claim 1 wherein said differential amplifier and said follower amplifier means are implemented as a hybrid circuit.
4. An active voltage probe according to claim 1 wherein the other end of said termination resistor receives a bias voltage to cancel bias currents from said probe head.
5. An active voltage probe according to claim 1 wherein said coaxial cable is connected to said output circuit via a coaxial connector.
6. An active voltage probe according to claim 1 wherein said follower amplifier means comprises a source follower amplifier.
7. An active voltage probe according to claim 1 wherein said follower amplifier means comprises a combination of a source follower amplifier and an emitter follower amplifier.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US252,749 | 1981-04-10 | ||
| US06/252,749 US4403183A (en) | 1981-04-10 | 1981-04-10 | Active voltage probe |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1199069A true CA1199069A (en) | 1986-01-07 |
Family
ID=22957372
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000399660A Expired CA1199069A (en) | 1981-04-10 | 1982-03-29 | Active voltage probe |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US4403183A (en) |
| JP (1) | JPS57175961A (en) |
| CA (1) | CA1199069A (en) |
| DE (1) | DE3213039C2 (en) |
| FR (1) | FR2503872B1 (en) |
| GB (1) | GB2096775B (en) |
| NL (1) | NL8201340A (en) |
Families Citing this family (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5975157A (en) * | 1982-10-22 | 1984-04-27 | テクトロニクス・インコ−ポレイテツド | Trigger circuit |
| US4551636A (en) * | 1983-05-25 | 1985-11-05 | Tektronix, Inc. | Wide bandwidth signal coupling circuit having a variable voltage-level shift from input to output |
| JPH0625778B2 (en) * | 1985-07-19 | 1994-04-06 | 光一 吉田 | Contact type multi-probe |
| FR2595887A1 (en) * | 1986-03-14 | 1987-09-18 | Labo Electronique Physique | INTENUATOR WITH HIGH INPUT, MULTI-CHANNEL HIGH FREQUENCY, AND OSCILLOSCOPE AND ACTIVE PROBE COMPRISING SUCH ATTENUATOR |
| US4758779A (en) * | 1986-04-07 | 1988-07-19 | Tektronix, Inc. | Probe body for an electrical measurement system |
| US4779042A (en) * | 1986-12-23 | 1988-10-18 | Grumman Aerospace Corporation | Computer-aided probe with tri-state circuitry test capability |
| US4963812A (en) * | 1989-10-02 | 1990-10-16 | Motorola, Inc. | Battery charger housing for batteries of differing dimensions |
| US5672997A (en) * | 1994-09-21 | 1997-09-30 | Intel Corporation | Method and apparatus for reducing the nominal operating voltage supplied to an integrated circuit |
| US5583447A (en) * | 1995-02-03 | 1996-12-10 | Hewlett-Packard Company | Voltage probe with reverse impedance matching |
| US6351112B1 (en) * | 1998-08-31 | 2002-02-26 | Agilent Technologies, Inc. | Calibrating combinations of probes and channels in an oscilloscope |
| US6271712B1 (en) * | 1999-04-07 | 2001-08-07 | Semiconductor Components Industries Llc | Synchronous rectifier and method of operation |
| US6462528B1 (en) * | 2000-05-23 | 2002-10-08 | Tektronix, Inc. | Method and apparatus for probing a conductor of an array of closely-spaced conductors |
| DE10131350A1 (en) * | 2001-06-28 | 2003-02-06 | Egm Entwicklung Montage | Circuit arrangement for measurement of sensor current or voltage, especially for use with an inductive displacement sensor, has its extension cable between load resistance and measurement circuit to avoid capacitance interference |
| TWI273250B (en) * | 2004-06-28 | 2007-02-11 | Richtek Technology Corp | A sensor apparatus without being influenced by bias electric current and the method thereof |
| JP4910520B2 (en) * | 2006-07-07 | 2012-04-04 | 横河電機株式会社 | Active probe |
| US7795860B2 (en) * | 2006-08-16 | 2010-09-14 | Tektronix, Inc. | Multiple probe acquisition system |
| DE102008009962A1 (en) * | 2007-12-04 | 2009-06-10 | Rohde & Schwarz Gmbh & Co. Kg | Probe with high accuracy DC voltage measurement |
| CN102053177B (en) * | 2009-11-10 | 2014-12-10 | 北京普源精电科技有限公司 | Active differential voltage probe |
| US10408861B2 (en) * | 2015-03-04 | 2019-09-10 | Rohde & Schwarz Gmbh & Co. Kg | Circuit for compensating an offset voltage in an amplifier |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3256484A (en) * | 1962-09-10 | 1966-06-14 | Tektronix Inc | High voltage test probe containing a part gas, part liquid dielectric fluid under pressure and having a transparent housing section for viewing the presence of the liquid therein |
| DE1591450A1 (en) * | 1967-03-16 | 1969-11-06 | Siemens Ag | Arrangement for balancing electrical voltages |
| US3533004A (en) * | 1968-11-13 | 1970-10-06 | Electronic Associates | Feed forward amplifier |
| US3943367A (en) * | 1975-06-10 | 1976-03-09 | The United States Of America As Represented By The Secretary Of The Army | High frequency optically coupled differential voltage probe with logarithmic response |
| US4042881A (en) * | 1975-06-23 | 1977-08-16 | Unitec, Inc. | Voltage measuring device having an amplifier in the probe |
| US4209742A (en) * | 1976-10-13 | 1980-06-24 | Tektronix, Inc. | Modular probe system |
| DE2810951C2 (en) * | 1978-03-14 | 1980-02-07 | Hewlett-Packard Gmbh, 7030 Boeblingen | Compensation circuit for electronic measuring devices |
| IL55101A0 (en) * | 1978-07-07 | 1978-09-29 | Kibbutz Mishmar Hanegev | Electronic circuit |
-
1981
- 1981-04-10 US US06/252,749 patent/US4403183A/en not_active Expired - Fee Related
-
1982
- 1982-03-25 JP JP57048098A patent/JPS57175961A/en active Pending
- 1982-03-29 CA CA000399660A patent/CA1199069A/en not_active Expired
- 1982-03-31 NL NL8201340A patent/NL8201340A/en not_active Application Discontinuation
- 1982-04-06 DE DE3213039A patent/DE3213039C2/en not_active Expired
- 1982-04-07 GB GB8210258A patent/GB2096775B/en not_active Expired
- 1982-04-09 FR FR8206699A patent/FR2503872B1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| FR2503872A1 (en) | 1982-10-15 |
| JPS57175961A (en) | 1982-10-29 |
| GB2096775A (en) | 1982-10-20 |
| NL8201340A (en) | 1982-11-01 |
| GB2096775B (en) | 1984-09-26 |
| FR2503872B1 (en) | 1986-04-11 |
| US4403183A (en) | 1983-09-06 |
| DE3213039A1 (en) | 1982-10-28 |
| DE3213039C2 (en) | 1985-10-03 |
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