WO2000019302A1 - Spikefreie taktumschaltung - Google Patents
Spikefreie taktumschaltung Download PDFInfo
- Publication number
- WO2000019302A1 WO2000019302A1 PCT/DE1999/003058 DE9903058W WO0019302A1 WO 2000019302 A1 WO2000019302 A1 WO 2000019302A1 DE 9903058 W DE9903058 W DE 9903058W WO 0019302 A1 WO0019302 A1 WO 0019302A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- flip
- flop
- input
- clock
- gate
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J3/00—Time-division multiplex systems
- H04J3/02—Details
- H04J3/06—Synchronising arrangements
- H04J3/0635—Clock or time synchronisation in a network
- H04J3/0685—Clock or time synchronisation in a node; Intranode synchronisation
- H04J3/0688—Change of the master or reference, e.g. take-over or failure of the master
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F1/00—Details not covered by groups G06F3/00 - G06F13/00 and G06F21/00
- G06F1/04—Generating or distributing clock signals or signals derived directly therefrom
- G06F1/08—Clock generators with changeable or programmable clock frequency
Definitions
- the subject matter of the application relates to a circuit arrangement for switching from a first clock signal to a second clock signal, comprising the features of the preamble of claim 1.
- the object of the application sets itself the task of specifying a circuit arrangement for switching over between clock signals which can be completely implemented as a digital circuit in an integrated circuit and which allows any phase position of the clock signals.
- the circuit arrangement according to the application is purely digital, it does not require any discrete components, so that it can be ner integrated circuit, such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Flash Program able Gate Array) can be implemented.
- the circuit arrangement can be loaded with an asynchronous signal for switching between the clock signals.
- the phase position of the clock signals is arbitrary.
- FIG. 1 shows a block diagram of a circuit arrangement for switching over between clock signals
- FIG. 2 shows a circuit diagram of a circuit arrangement according to the application for switching between clock signals at gate level
- Figure 3 is a signal state diagram of possible states of individual signals when switching from one
- Figure 4 is a state diagram of other possible states of individual signals when switching from one clock signal to another clock signal.
- the clock selection circuit CS (for: Clock Selection), which is supplied on the input side with a clock selection signal CLKSEL, a first clock signal BOCLK, a second clock signal B1CLK, a first clock alarm signal BOCLKALA and a second clock alarm signal BICLKALA, outputs the output clock signal BS BCMCLK on the output side.
- the clock selection circuit in FIG. 2 has two identical circuit parts, the first circuit part shown above being assigned to the first clock signal and the second circuit part shown below being assigned to the second clock signal.
- the clock selection signal CLKSEL is inverted to the second circuit part as the second clock selection signal B1CLKSEL and, via an inverter INV, is fed to the first circuit part as the first clock selection signal BOCLKSEL.
- a flip-flop FF 01 in the first circuit part is supplied with the first clock selection signal BOCLKSEL at its data input D and the first clock signal BOCLK at its clock input.
- a second flip-flop FF02 in the first circuit part is supplied with the signal emitted by the first flip-flop at the output Q at its data input D and the clock signal BOCLK at its clock input CLK.
- the first clock selection signal BOCLKSEL and the signal emitted at the output Q of the flip-flop FF02 are supplied on the input side to a logic AND gate ANDOl.
- a flip-flop FF03 is at its input labeled D with the signal output by the AND gate ANDOl, at its inverting clock input CLK with the first clock signal
- the signal emitted by the flip-flop FF3 at its output Q forms an enable signal B0EN for the first clock signal BOCLK.
- the enable signal B ⁇ EN for the first clock signal BOCLK and the first clock signal BOCLK is supplied to a logic AND gate AND02 on the input side.
- the second circuit part for the second clock signal is basically constructed in the same way as the first circuit part for the first clock signal.
- a logic element VKG to the input side of which the signals emitted by the AND gate AND02 and the AND gate AND12 are supplied, outputs the selected clock signal BS BCMCLK at its output.
- the clock changeover takes place in two phases. If the clock signals are switched, which is shown in FIGS. 3 and 4 in line BOCLKSEL by a change in the state of the clock selection signal from the logic high level (H) to the logic low level (L), the clock signal which has been switched through as the output clock signal (in FIG. 3 and FIG. 4 the first clock signal BOCLK) with the first falling edge of this clock signal.
- the clock signal that has not been switched through as the output clock signal (the clock signal B1CLK in FIG. 3 and FIG. 4) is switched on during its logically low level.
- the connection takes place with a delay which results in a clock gap of, as shown in FIG. 3, a minimum of one clock period and, as shown in FIG. 4, a maximum of three clock periods.
- the first clock signal and the second clock signal can be given by mutually complementary clock signals.
- the circuit arrangement ensures that if the clock alarm signal is active, it is not possible to switch to the associated clock signal.
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP99969807A EP1118055B1 (de) | 1998-09-29 | 1999-09-23 | Spikefreie taktumschaltung |
US09/806,104 US6411134B1 (en) | 1998-09-29 | 1999-09-23 | Spike-free clock switching |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19844671.3 | 1998-09-29 | ||
DE19844671A DE19844671C1 (de) | 1998-09-29 | 1998-09-29 | Spikefreie Taktumschaltung |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2000019302A1 true WO2000019302A1 (de) | 2000-04-06 |
Family
ID=7882670
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/DE1999/003058 WO2000019302A1 (de) | 1998-09-29 | 1999-09-23 | Spikefreie taktumschaltung |
Country Status (6)
Country | Link |
---|---|
US (1) | US6411134B1 (de) |
EP (1) | EP1118055B1 (de) |
CN (1) | CN1320233A (de) |
DE (1) | DE19844671C1 (de) |
ES (1) | ES2191494T3 (de) |
WO (1) | WO2000019302A1 (de) |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100689724B1 (ko) * | 2000-01-28 | 2007-03-09 | 후지쯔 가부시끼가이샤 | 핫 플러그에 대응한 클록 전환 회로 |
US6960942B2 (en) * | 2001-05-18 | 2005-11-01 | Exar Corporation | High speed phase selector |
US6693477B2 (en) * | 2001-10-22 | 2004-02-17 | Research In Motion Limited | Clock circuit for a microprocessor |
CN1300972C (zh) * | 2003-07-14 | 2007-02-14 | 松下电器产业株式会社 | 时钟信号切换装置、时钟信号切换方法、数据总线切换装置及数据总线切换方法 |
JP2005191877A (ja) * | 2003-12-25 | 2005-07-14 | Fujitsu Ltd | クロック切り替え回路 |
CN101299159B (zh) * | 2008-07-01 | 2010-06-09 | 深圳市远望谷信息技术股份有限公司 | 时钟切换电路 |
CN102012717B (zh) * | 2010-11-16 | 2012-10-03 | 青岛海信信芯科技有限公司 | 一种时钟切换方法及时钟切换装置 |
CN116318071A (zh) * | 2023-05-22 | 2023-06-23 | 合肥智芯半导体有限公司 | 时钟切换电路、时钟切换方法 |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH01150921A (ja) * | 1987-12-08 | 1989-06-13 | Ricoh Co Ltd | Clk切替回路 |
US4970405A (en) * | 1987-12-11 | 1990-11-13 | Nec Corporation | Clock selection circuit for selecting one of a plurality of clock pulse signals |
US5652536A (en) * | 1995-09-25 | 1997-07-29 | Cirrus Logic, Inc. | Non-glitch clock switching circuit |
JPH10124167A (ja) * | 1996-10-17 | 1998-05-15 | Miyagi Oki Denki Kk | システムクロック切り換え装置 |
Family Cites Families (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4282493A (en) * | 1979-07-02 | 1981-08-04 | Motorola, Inc. | Redundant clock signal generating circuitry |
GB8615399D0 (en) * | 1986-06-24 | 1986-07-30 | Int Computers Ltd | Switching circuit |
US4853653A (en) * | 1988-04-25 | 1989-08-01 | Rockwell International Corporation | Multiple input clock selector |
JP2739964B2 (ja) * | 1988-09-28 | 1998-04-15 | 株式会社東芝 | クロック切替回路 |
CA2015488C (en) * | 1989-04-30 | 1997-07-08 | Tomoyasu Tsuda | Polyurethane, process for its production and polyester diol used for its production |
US5155380A (en) * | 1991-04-12 | 1992-10-13 | Acer Incorporated | Clock switching circuit and method for preventing glitch during switching |
US5315181A (en) * | 1993-07-07 | 1994-05-24 | Maxtor Corporation | Circuit for synchronous, glitch-free clock switching |
JPH10154021A (ja) * | 1996-09-30 | 1998-06-09 | Toshiba Corp | クロック切換装置およびクロック切換方法 |
US6107841A (en) * | 1998-09-08 | 2000-08-22 | International Business Machines Corporation | Synchronous clock switching circuit for multiple asynchronous clock source |
-
1998
- 1998-09-29 DE DE19844671A patent/DE19844671C1/de not_active Expired - Fee Related
-
1999
- 1999-09-23 ES ES99969807T patent/ES2191494T3/es not_active Expired - Lifetime
- 1999-09-23 CN CN99811540.1A patent/CN1320233A/zh active Pending
- 1999-09-23 WO PCT/DE1999/003058 patent/WO2000019302A1/de active IP Right Grant
- 1999-09-23 US US09/806,104 patent/US6411134B1/en not_active Expired - Fee Related
- 1999-09-23 EP EP99969807A patent/EP1118055B1/de not_active Expired - Lifetime
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH01150921A (ja) * | 1987-12-08 | 1989-06-13 | Ricoh Co Ltd | Clk切替回路 |
US4970405A (en) * | 1987-12-11 | 1990-11-13 | Nec Corporation | Clock selection circuit for selecting one of a plurality of clock pulse signals |
US5652536A (en) * | 1995-09-25 | 1997-07-29 | Cirrus Logic, Inc. | Non-glitch clock switching circuit |
JPH10124167A (ja) * | 1996-10-17 | 1998-05-15 | Miyagi Oki Denki Kk | システムクロック切り換え装置 |
US5969558A (en) * | 1996-10-17 | 1999-10-19 | Oki Electric Industry Co., Ltd. | Abnormal clock signal detector and switching device |
Non-Patent Citations (3)
Title |
---|
ANONYMOUS: "Method to Select One of Two Clocks While Avoiding Narrow Pulses.", IBM TECHNICAL DISCLOSURE BULLETIN, vol. 32, no. 9B, 1 February 1990 (1990-02-01), New York, US, pages 82 - 84, XP000082242 * |
PATENT ABSTRACTS OF JAPAN vol. 013, no. 412 (P - 932) 12 September 1989 (1989-09-12) * |
PATENT ABSTRACTS OF JAPAN vol. 1998, no. 10 31 August 1998 (1998-08-31) * |
Also Published As
Publication number | Publication date |
---|---|
EP1118055B1 (de) | 2003-01-08 |
CN1320233A (zh) | 2001-10-31 |
DE19844671C1 (de) | 1999-10-07 |
US6411134B1 (en) | 2002-06-25 |
ES2191494T3 (es) | 2003-09-01 |
EP1118055A1 (de) | 2001-07-25 |
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