WO2000072121A1 - Clock system for multiple component system - Google Patents
Clock system for multiple component system Download PDFInfo
- Publication number
- WO2000072121A1 WO2000072121A1 PCT/EP2000/004209 EP0004209W WO0072121A1 WO 2000072121 A1 WO2000072121 A1 WO 2000072121A1 EP 0004209 W EP0004209 W EP 0004209W WO 0072121 A1 WO0072121 A1 WO 0072121A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- clock
- clock signal
- bus
- module
- sample
- Prior art date
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Classifications
-
- 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
- G06F1/10—Distribution of clock signals, e.g. skew
Definitions
- This invention relates to the field of electronic systems, and in particular to systems comprising components having multiple clocked components or modules.
- a bus-clock is provided to synchronize the communications among the modules. That is, reliable bus communications among modules requires that the data being communicated is stable at the times when the communication is to actually occur.
- the bus-clock identifies these stable communication times.
- a module writes its data to the bus sufficiently ahead of the communication time so that it is stable when the communication time occurs, and a module reads the data from the bus when the communication time occurs, as identified by a bus-clock transition.
- the actual time that a module reads the data will not coincide exactly with the time that the bus-clock transition occurs, and therefore the writing module must maintain the stability of the data within some specified tolerance band before and after the transition, and no other module may initiate a write to the bus, for example, in anticipation of the next bus-clock transition, within this specified tolerance band.
- Each module that reads data from the bus must effect its read operation within this tolerance band.
- the width of the tolerance band before and after the bus-clock transitions limits the speed at which the bus-clock transitions can occur, and therefore limits the achievable data transfer rate via the bus. Narrowing the tolerance band, however, requires tighter design and fabrication rules to assure that modules conform to the tighter limits, and therefore increase the cost of the modules. In a typical design, the ever increasing demand for higher system performance forces the bus-clock speed to "push the limit", allowing for as little tolerance as possible to achieve the highest speed possible.
- each module is typically iteratively designed and redesigned to assure that the data is read from or written to the bus at precisely the right time. That is, each module's clock is adjusted or redesigned so that it is synchronous in phase with the bus-clock at its particular location on the chip or board, with its particular routing path and associated delay parameters.
- This iterative design process is costly, and often results in significant program schedule slippage as the interactions of each of the modules and each of the design or layout changes produce an increasingly difficult set of design and timing tradeoffs and constraints.
- a common technique is the use of self-synchronizing design techniques.
- the module can include a Phase-Locked-Loop (PLL), which, as its name implies, locks the phase of the module's data transfer clock to the phase of the bus-clock. That is, rather than physically adjusting each module's clock to match the phase of the bus-clock, the PLL effects this matching electronically and automatically.
- PLL Phase-Locked-Loop
- each module in this alternative must include a PLL to effect an accurate phase matching.
- additional costs associated with adding a PLL circuit to each module include the additional cost of the components used, the additional cost of testing each PLL, the consumption of area on the chip or board to accommodate each PLL, and the like.
- conventional PLLs include analog components, which, as is known in the art, are inherently more difficult and costly to design and fabricate than digital components, and which do not scale as easily to newer technologies as digital components. Also, each PLL consumes a significant amount of power compared to digital components.
- a clock module that operates in conjunction with the generation of the bus-clock signal to provide a combination of module-clocks that can be relied upon to provide an adequate safety margin for data transfers among processing modules at the speed of the bus-clock.
- a master- clock generates the bus-clock and a sample-clock, the sample-clock having a predetermined phase relationship with respect to the bus-clock.
- Base-clocks at each of the frequencies required for each processing module are generated in the conventional manner, and, in accordance with this invention, are sampled by the sample-clock to produce sampled module- clocks that are provided to each corresponding processing module.
- each module-clock By sampling each base- clock with a sample-clock that has a corresponding predetermined phase relationship with respect to the bus-clock, each module-clock will have a predetermined phase relationship with respect to the bus-clock. By selecting the predetermined phase relationship appropriately, an optimal data transfer speed can be achieved.
- FIG. 1 illustrates an example block diagram of a processing system having a clock module in accordance with this invention.
- FIG. 2 illustrates an example block diagram of a clock module in accordance with this invention.
- FIG. 3 illustrates an example timing diagram of a processing system in accordance with this invention.
- FIG. 4 illustrates an example flow diagram of a clock module for a processing system in accordance with this invention.
- FIG. 1 illustrates an example block diagram of a processing system 100 having a clock module 120 in accordance with this invention.
- the processing system 100 comprises one or more processing modules 131-133 that communicate with each other via a common bus 150.
- the processing modules 131-133 are used herein as paradigms for devices that perform some function in dependence upon a clocking signal 121-123, respectively, and which communicate with each other, and potentially with other devices, via the common bus 150.
- the processing module may be a state machine that responds to input data from the bus 150, and produces output data to the bus 150; it may be a printer controller that initiates a sequence of commands to effect the printing of characters or images that are communicated to it via the bus 150; it may be a CD player controller that reads the contents of a currently loaded disk and present the contents to the bus 150 for subsequent printout by the aforementioned printer controller; and so on.
- the clock module 120 provides the necessary module-clock signals 121-123 for each of the processing modules 131-133. In accordance with one aspect of this invention, the clock module 120 also provides the common bus-clock signal 125. The clock module 120 provides these module-clock signals 121-123 and bus-clock signal 125 based upon a master- clock signal 101, to facilitate synchronization and other time related operations. In accordance with this invention, each module-clock signal 121-123 has a predetermined phase relationship with the bus-clock 125.
- FIG. 2 illustrates an example block diagram of a clock module 120 in accordance with this invention.
- the example clock module 120 generates the module-clock signals A-clock 121, B-clock 122, and K-clock 123 that have a predetermined phased relationship with the bus-clock signal 125.
- the predetermined phase is determined to provide a safety margin between the transitions of the data being placed on the bus 150 from the modules 131-133 and the transitions of the bus-clock 125 that control the data transfer on the bus 150.
- Providing the predetermined phase relationship in the example clock-module 120 is effected by sampling, via samplers 221-223, corresponding base-clock signals 281-283 with a sample-clock 241 that also has a predetermined phase relationship with the bus-clock 125.
- the sample-clock 241 is derived from a master clock signal that has a frequency which is "n" times the frequency of the bus- clock 125, where n is an integer.
- the bus-clock 125 is derived from this master clock signal, via the f/n frequency divider 230.
- the phase shift of the sample-clock 241 that is introduced by the phase shift module 240 relative to the master clock is also the phase shift of the sample-clock 241 relative to the bus-clock 125.
- Alternative arrangements for providing a signal that has a fixed phase relationship to another signal are commonly known in the art.
- the base-clock signals 281-283 are the clock signals that are required by the corresponding processing modules, each processing module having a potentially different requirement.
- the particular frequency of each base-clock signal 281-283 is defined using techniques common to the art of system design.
- the frequency of each base- clock signal is an integer fraction of frequency of the bus-clock 125, to avoid a changing phase relationship among modules.
- one processing module may be configured to operate at one third the frequency of the bus-clock, another at one half, and yet another at the same frequency as the bus-clock.
- n is the integer divisor that provides the bus-clock frequency
- A, B, and K are integer divisors that provide each module clock frequency relative to the bus-clock.
- Alternative arrangements for providing each base-clock signal 281-283 having a fixed frequency relationship to the bus-clock 125 are commonly known in the art.
- FIG. 3 is an example timing diagram that illustrates the effects of this sampling process on the base-clock signals 281-283.
- the sample-clock 241 is phase shifted 303 relative to the bus-clock 125 that is illustrated on line 3B.
- FIGs. 3 are the base-clock signals 281, 282, and 283, which are not at the desired predetermined phase relationship to the bus clock 125.
- the base-clock signals 281-283 are illustrated as having the same phase relationship with each other and with the bus-clock 150, although, as will be evident to one of ordinary skill in the art in view of this invention, the phase of each of the base-clock signals 281-283 relative to the bus-clock 125 need only be less than the aforementioned predetermined phase. Illustrated on lines 3E, 3G, and 3J are the resultant sampled module-clock signals 121-123 respectively. As can be seen, the rising edge 311-313 of the module-clock signals 121-123 correspond to a rising edge 350 of the sample clock 241, and the falling edge 321-323 of the module-clock signals 121-123 also correspond to a rising edge 351-353 of the sample-clock 241, respectively.
- the sampler 221-223 may be a conventional flip-flop having the base-clock signal 281-283 as input, that is edge triggered by the sample-clock 241.
- phase shift introduced by each sampler 221-223 will be considered equal and substantially zero, and thus the predetermined phase shift of each sampled clock signal 121-123 is substantially equal to the predetermined phase shift 303 of the sample-clock 241, as illustrated in FIG. 3.
- the predetermined phase shift 303 can be determined using timing analysis techniques common in the art. To assure reliable operation, an estimated skew of each clock signal 121-123 from the clock module 120 to its corresponding processing module 131-133 is determined based on estimated propagation delays. To this estimated skew is added the required phase shift between the clock signal 121-123 and the bus-clock 125, based on the characteristics of the data transfer devices in the corresponding processing module 131-133 used to access the bus 150, or based on a general specification related to all devices that access the bus 150, to provide a total phase shift associated with each clock signal 121-123.
- the predetermined phase 303 of the sample-clock 241 is determined to be the maximum of the total phase shift associated with each clock signal 121-123 plus a safety margin.
- a safety margin is dependent upon a variety of factors. Often these factors are design constraints which determine the predetermined phase 303, from which the safety margin is computed (predetermined phase 303 minus the maximum of the total phase shift of each clock signal 121-123).
- the phase shift module 240 may be a simple inverter, which provides a fixed phase shift that is substantially equal to 180 degrees.
- the frequency of the bus-clock 125 may be a predetermined frequency based on an interface requirement to higher level systems, or based on compliance with an industry standard. If, given such system design constraints, the determined safety margin fails to satisfy an individual or corporate goal or criteria, the design constraints are reassessed, design changes or requirements changes are made, and the safety margin is recomputed and assessed. Although this process may be iteratively repeated until an appropriate safety margin is achieved, it can be performed well in advance of, and at significantly less cost than, a layout or fabrication of the completed design, as often occurs using conventional module clock design techniques. As illustrated by the example block diagram of FIG.
- a clock module 120 in accordance with this invention can be implemented using digital frequency dividers 271-273 and samplers 221-223, thereby obviating the need for an analog PLL circuit associated with each processing module 131-133, as discussed above with regard to prior art systems.
- the phase shift module 240 in a preferred embodiment is also implemented using only digital logic, such as the aforementioned inverter that provides a 180 degree phase shift, or, if the master clock is more than twice the bus-clock frequency, a ring-shift register that provides a selection of discrete submultiples of the bus-clock period.
- FIG. 4 illustrates an example flow diagram for generating clock signals in accordance with this invention, as might be employed in the example clock module 120 of the processing system 100, and will be used to illustrate a few example alternative arrangements.
- the bus-clock is generated, using for example the frequency divider 230 of FIG. 2, and at 420 the sample-clock is generated at a fixed phase from the bus- clock.
- an external source may provide the bus-clock, in which case the sample- clock would be synchronized to this externally provided bus-clock, at the predetermined fixed phase, using synchronization techniques common in the art.
- the loop 430-460 effects the generation 440 of each base-clock and the sampling 450 of this base-clock, using for example the frequency dividers 271-273 and sampleers 221-223 of FIG. 2.
- one or more of the base-clocks may be generated externally, for example, at the corresponding processing module.
- the corresponding sampler will provide a sampled module-clock that is precisely phased with the bus-clock.
- multiple sample clocks may be employed to provide differing predetermined phases to one or more of the processing modules. For example, devices that read data from the bus may be provided clock signals having one predetermined phase delay, devices that write data to the bus provided clock signals having an other predetermined phase delay, and devices that read and write data provided both clock signals, or another clock signal having a third predetermined phase, and so on.
- the particular configurations and structures are provided in the figures for illustration only. Alternative configurations, such as the incorporation of the clock module 120 within one of the processing modules 131-133 would be evident to one of ordinary skill in the art.
- the functional blocks may be implemented in hardware, software, or a combination of both.
- the functions of the frequency dividers 271-273 may be embodied in programming code that is executed in an embedded processor, or programming code that effects the creation of a programmed logic array that operates as a state machine to effect the required functions, while the samplers 221-223 may be conventional logic gates.
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- Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Physics & Mathematics (AREA)
- General Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Information Transfer Systems (AREA)
- Synchronisation In Digital Transmission Systems (AREA)
- Manipulation Of Pulses (AREA)
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE60021983T DE60021983T2 (en) | 1999-05-24 | 2000-05-04 | CLOCK SYSTEM FOR MULTICOMPONENT SYSTEM |
EP00938628A EP1099149B1 (en) | 1999-05-24 | 2000-05-04 | Clock system for multiple component system |
JP2000620448A JP2003500723A (en) | 1999-05-24 | 2000-05-04 | Clock system for multiple component system |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/316,983 | 1999-05-24 | ||
US09/316,983 US6434706B1 (en) | 1999-05-24 | 1999-05-24 | Clock system for multiple component system including module clocks for safety margin of data transfers among processing modules |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2000072121A1 true WO2000072121A1 (en) | 2000-11-30 |
Family
ID=23231592
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/EP2000/004209 WO2000072121A1 (en) | 1999-05-24 | 2000-05-04 | Clock system for multiple component system |
Country Status (8)
Country | Link |
---|---|
US (2) | US6434706B1 (en) |
EP (1) | EP1099149B1 (en) |
JP (1) | JP2003500723A (en) |
KR (1) | KR100661673B1 (en) |
CN (1) | CN1171132C (en) |
DE (1) | DE60021983T2 (en) |
TW (1) | TW533346B (en) |
WO (1) | WO2000072121A1 (en) |
Families Citing this family (19)
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US6434706B1 (en) * | 1999-05-24 | 2002-08-13 | Koninklijke Philips Electronics N.V. | Clock system for multiple component system including module clocks for safety margin of data transfers among processing modules |
US6650101B2 (en) * | 2002-04-08 | 2003-11-18 | Agilent Technologies, Inc. | Timebase for sampling an input signal having a synchronous trigger |
US6573761B1 (en) * | 2002-04-08 | 2003-06-03 | Agilent Technologies, Inc. | Timebase for sampling an applied signal having a synchronous trigger |
US7111186B2 (en) * | 2003-04-28 | 2006-09-19 | Sun Microsystems, Inc. | Method and apparatus for static phase offset correction |
CN100397791C (en) * | 2003-08-06 | 2008-06-25 | 华为技术有限公司 | ASIC realizing method for transmission system overhead processing chip side clock domain switching circuit |
KR100990484B1 (en) * | 2004-03-29 | 2010-10-29 | 삼성전자주식회사 | Transmission clock signal generator for serial bus communication |
US7844847B2 (en) * | 2006-09-18 | 2010-11-30 | Samsung Electronics Co., Ltd. | System and method for tuning power consumption and group delay in wireless RFICs |
US7685458B2 (en) * | 2006-12-12 | 2010-03-23 | Kabushiki Kaisha Toshiba | Assigned task information based variable phase delayed clock signals to processor cores to reduce di/dt |
US7574548B2 (en) * | 2007-09-12 | 2009-08-11 | International Business Machines Corporation | Dynamic data transfer control method and apparatus for shared SMP computer systems |
US7965111B2 (en) * | 2008-04-29 | 2011-06-21 | Qualcomm Incorporated | Method and apparatus for divider unit synchronization |
JP5432749B2 (en) * | 2010-02-01 | 2014-03-05 | トヨタ自動車株式会社 | In-vehicle electronic control device with multi-core processor |
US8564330B1 (en) * | 2012-06-05 | 2013-10-22 | Xilinx, Inc. | Methods and systems for high frequency clock distribution |
WO2014014520A1 (en) * | 2012-07-18 | 2014-01-23 | Intel Corporation | Measuring time offsets between devices with independent silicon clocks |
JP2016508258A (en) * | 2012-12-13 | 2016-03-17 | コーヒレント・ロジックス・インコーポレーテッド | Clock distribution network for multi-frequency multiprocessor systems. |
US20190050020A1 (en) * | 2017-08-10 | 2019-02-14 | Qualcomm Incorporated | Clock Signal Staggering with Clock Frequency Adjustment |
WO2019199609A1 (en) * | 2018-04-09 | 2019-10-17 | The Regents Of The University Of California | Quarter-rate serial-link receiver with low-aperture-delay samplers |
CN112559268B (en) * | 2020-12-18 | 2024-04-26 | 北京华峰测控技术股份有限公司 | Test apparatus, test method, and computer-readable storage medium |
US11764834B2 (en) | 2022-02-15 | 2023-09-19 | Raytheon Company | Device for and method of synchronizing multiple beamforming devices |
CN115877914B (en) * | 2023-01-17 | 2024-02-20 | 北京象帝先计算技术有限公司 | Signal control method, sampling method, device, system and electronic equipment |
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1999
- 1999-05-24 US US09/316,983 patent/US6434706B1/en not_active Expired - Lifetime
-
2000
- 2000-05-04 CN CNB008009813A patent/CN1171132C/en not_active Expired - Fee Related
- 2000-05-04 EP EP00938628A patent/EP1099149B1/en not_active Expired - Lifetime
- 2000-05-04 DE DE60021983T patent/DE60021983T2/en not_active Expired - Lifetime
- 2000-05-04 WO PCT/EP2000/004209 patent/WO2000072121A1/en active IP Right Grant
- 2000-05-04 JP JP2000620448A patent/JP2003500723A/en not_active Withdrawn
- 2000-05-04 KR KR1020017000973A patent/KR100661673B1/en not_active IP Right Cessation
- 2000-05-22 TW TW089109837A patent/TW533346B/en not_active IP Right Cessation
-
2002
- 2002-06-20 US US10/176,209 patent/US6640310B2/en not_active Expired - Lifetime
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EP0886214A1 (en) * | 1997-05-30 | 1998-12-23 | Hewlett-Packard Company | Multi-channel architecture with channel independent clock signals |
Also Published As
Publication number | Publication date |
---|---|
KR20010099599A (en) | 2001-11-09 |
CN1310814A (en) | 2001-08-29 |
US6434706B1 (en) | 2002-08-13 |
CN1171132C (en) | 2004-10-13 |
KR100661673B1 (en) | 2006-12-26 |
DE60021983T2 (en) | 2006-06-08 |
DE60021983D1 (en) | 2005-09-22 |
EP1099149A1 (en) | 2001-05-16 |
EP1099149B1 (en) | 2005-08-17 |
US20020157032A1 (en) | 2002-10-24 |
TW533346B (en) | 2003-05-21 |
US6640310B2 (en) | 2003-10-28 |
JP2003500723A (en) | 2003-01-07 |
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