WO2007080719A1 - クロック生成回路 - Google Patents
クロック生成回路 Download PDFInfo
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- WO2007080719A1 WO2007080719A1 PCT/JP2006/324006 JP2006324006W WO2007080719A1 WO 2007080719 A1 WO2007080719 A1 WO 2007080719A1 JP 2006324006 W JP2006324006 W JP 2006324006W WO 2007080719 A1 WO2007080719 A1 WO 2007080719A1
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- clock
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- generation circuit
- clock signal
- phase
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- 230000010363 phase shift Effects 0.000 claims abstract description 12
- 238000001514 detection method Methods 0.000 claims description 21
- 230000008859 change Effects 0.000 abstract description 6
- 238000010586 diagram Methods 0.000 description 21
- 238000001228 spectrum Methods 0.000 description 19
- 230000004048 modification Effects 0.000 description 7
- 238000012986 modification Methods 0.000 description 7
- 238000000034 method Methods 0.000 description 4
- 230000010355 oscillation Effects 0.000 description 4
- 238000012795 verification Methods 0.000 description 4
- 208000032365 Electromagnetic interference Diseases 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000013256 coordination polymer Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000005012 migration Effects 0.000 description 1
- 238000013508 migration Methods 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Classifications
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03L—AUTOMATIC CONTROL, STARTING, SYNCHRONISATION OR STABILISATION OF GENERATORS OF ELECTRONIC OSCILLATIONS OR PULSES
- H03L7/00—Automatic control of frequency or phase; Synchronisation
- H03L7/06—Automatic control of frequency or phase; Synchronisation using a reference signal applied to a frequency- or phase-locked loop
- H03L7/08—Details of the phase-locked loop
- H03L7/085—Details of the phase-locked loop concerning mainly the frequency- or phase-detection arrangement including the filtering or amplification of its output signal
- H03L7/093—Details of the phase-locked loop concerning mainly the frequency- or phase-detection arrangement including the filtering or amplification of its output signal using special filtering or amplification characteristics in the loop
-
- 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 present invention relates to a clock generation circuit having a spread spectrum clocking function.
- SSC spread spectrum clocking
- EMI electro magnetic interference
- FIG. 17 is a graph showing how the clock frequency changes based on the SSC function in the Serial ATA standard.
- Fig. 18 shows an example of the spectrum of the clock signal based on the SSC function in the Serial ATA standard.
- a clock generation circuit that realizes spread spectrum includes a PLL circuit that generates a clock signal having a plurality of types of phases, and a phase that periodically shifts the generated clock signal having a plurality of types of phases.
- An interpolation unit is provided, which is configured to select and output one clock signal from among the multiple types of clock signals generated by the phase interpolation unit (see, for example, Patent Document 1).
- the periodic phase shift is performed outside the loop of the PLL circuit, so if there is a phase shift during the phase shift, This appears as high frequency jitter in the output as it is. If a data signal containing high-frequency jitter is output, the receiving circuit may not receive this data, and connectivity between sets equipped with Serial ATA may be reduced.
- a PLL that receives a spread spectrum clock signal.
- Another possible method is to connect a circuit (referred to as the second-stage PLL circuit) and configure the clock generation circuit to cut high-frequency jitter by the low-pass filter characteristics of the second-stage PLL circuit.
- reference numeral 301 denotes a frequency modulation circuit that receives a reference clock signal REFCK and generates a spread spectrum clock signal CK-SSC.
- Reference numeral 302 denotes a second-stage PLL circuit that receives the clock signal CK-SSC and outputs the clock signal CKOUT.
- the second-stage PLL circuit is a general PLL circuit that consists of a phase comparator, charge pump circuit, secondary LPF (Low Pass Filter), VCO (voltage-controlled oscillator), and frequency divider. It is.
- the bandwidth (cut-off frequency) of the second-stage PLL circuit is set low in order to cut high-frequency jitter.
- the PLL circuit acts as a jitter filter for jitter having a frequency component higher than the bandwidth of the input clock signal.
- Patent Document 1 Japanese Patent Laid-Open No. 2005-184488
- Non-Patent Document 1 Serial ATA Workgroup "SATA: High Speed Serialized AT Attachment”, Revision 1. 0, 29— August— 2001
- the device that does not support the SSC function due to the narrow cap challenge of the clock recovery circuit is the connection partner.
- using spread spectrum clock signals can cause connectivity problems.
- the band of the second-stage PLL circuit is used to cut high-frequency jitter, for example, when the spectrum is spread. If the width (cut-off frequency) is set low, the accumulated jitter of the VCO in the second-stage PLL circuit will increase if the spectrum is not spread. There is a possibility that the sex is bad.
- the present invention has been made paying attention to the above-mentioned problem, can easily switch the presence or absence of the SSC function (on Z off), and even if the SSC function is turned on / off,
- the purpose is to provide a clock generation circuit that has poor connectivity due to increased jitter.
- one embodiment of the present invention provides:
- a clock generation circuit that generates a clock signal according to an input reference clock signal
- the clock signal that is not frequency-modulated and the frequency-modulating power A frequency modulation circuit that generates any one of the clock signals according to the reference clock signal is provided.
- one embodiment of the present invention provides
- the frequency modulation circuit includes:
- a multi-phase clock generation circuit that generates a multi-phase clock signal composed of a plurality of clock signals having a predetermined phase difference between them;
- a phase subdivision unit that shifts and outputs the phase of the multiphase clock signal generated by the multiphase clock generation circuit
- a clock selection unit that selects and outputs one clock signal from the power of the multiphase clock signal output from the phase subdivision unit;
- One of the second control patterns for changing the selection of the clock signal performed by the selection unit at a predetermined cycle is selected according to the selection signal, and the phase subdivision unit selects the control pattern.
- a clock signal output from the frequency modulation circuit is input, and a PLL circuit that switches a bandwidth in accordance with the selection signal is further provided.
- One embodiment of the present invention provides:
- the PLL circuit When the selection signal indicates that a clock signal with high frequency modulation is output, the PLL circuit lowers the bandwidth than when a clock signal without high frequency modulation is input. It is configured.
- one embodiment of the present invention provides:
- a register part that can be read and written from the outside
- a register reference unit that reads information from the register unit and generates and outputs the selection signal
- One embodiment of the present invention provides:
- the selection signal is fixed to a predetermined logic level.
- One embodiment of the present invention provides:
- the PLL circuit includes a low-pass filter having a resistor and a capacitive element, and a charge pump.
- the PLL circuit is configured to switch a bandwidth by switching both a resistance value of a resistor and a capacitance value of a capacitive element included in the low-pass filter, and a current amount of the charge pump. To do.
- one embodiment of the present invention provides
- the selection signal is valid when the PLL circuit is locked.
- a PLL circuit that receives a clock signal output from the frequency modulation circuit and switches a bandwidth in accordance with the input bandwidth control signal
- a frequency modulation detection circuit that detects whether or not the frequency modulation is applied to the clock signal output from the frequency modulation circuit, and outputs a bandwidth control signal corresponding to the detection result to the PLL circuit;
- One embodiment of the present invention includes
- the bandwidth control signal indicates that frequency modulation is strong
- the frequency modulation is applied and the bandwidth is lower than when the clock signal is input. It is comprised and is characterized by the above.
- one embodiment of the present invention provides
- the frequency modulation detection circuit is composed of only a digital circuit.
- FIG. 1 is a block diagram showing a configuration of a clock generation circuit according to the first embodiment.
- FIG. 2 is a block diagram showing a configuration example of a frequency modulation circuit 110.
- FIG. 3 is a diagram showing a relationship between a phase control signal output from a modulation control unit 112 and a phase shift amount.
- FIG. 4 is a block diagram showing a configuration example of the phase subdivision unit 113.
- FIG. 5 is a diagram showing clock signals selected in each operation mode.
- FIG. 6 is a block diagram showing a configuration example of the clock selection unit 114.
- FIG. 7 is a block diagram showing a configuration example of the PLL circuit 120.
- FIG. 8 is a block diagram showing a configuration example of a low-pass filter 120c.
- FIG. 9 is a diagram showing values of parameters that are switched according to SSC-EN.
- FIG. 10 is a state transition diagram of the frequency modulation circuit 110.
- FIG. 10 is a state transition diagram of the frequency modulation circuit 110.
- FIG. 11 is a diagram showing a frequency change of the frequency modulation circuit 110 when SSC is on.
- FIG. 12 is a diagram showing a frequency change of the frequency modulation circuit 110 when SSC is off.
- FIG. 13 shows a configuration of a clock generation circuit according to a modification of the first embodiment.
- FIG. 14 is a block diagram showing a configuration of a clock generation circuit according to another modification of the first embodiment.
- FIG. 15 is a block diagram showing a configuration of a clock generation circuit according to the second embodiment.
- FIG. 16 is a block diagram showing a configuration example of a frequency modulation detection circuit 220.
- FIG. 17 is a diagram showing a change in frequency of a clock signal when SSC is on in the Serial ATA standard.
- FIG. 18 is a diagram showing an example of a spectrum of a clock signal when SSC is on in the Serial ATA standard.
- FIG. 19 is a diagram illustrating an example of a conventional clock generation circuit configured to cut high-frequency jitter.
- FIG. 1 is a block diagram showing a configuration of a clock generation circuit 100 according to Embodiment 1 of the present invention.
- the clock generation circuit 100 includes a frequency modulation circuit 110 and a PLL circuit 120, and further includes a terminal to which the reference clock signal REFCK is input, a terminal to output the output clock signal CKOUT, and an SSC It has a terminal to which the selection signal SSC—EN for switching on / off of (spread spectrum clocking) is input.
- the frequency modulation circuit 110 generates a clock signal based on the input reference clock REFCK and generates the clock signal CK-SSC as a clock signal CK-SSC. It outputs to the PLL circuit 120. That is, the frequency modulation circuit 110 switches the SSC function on and off according to the selection signal SSC-EN.
- the input reference clock REFCK is 25 MHz.
- the clock signal CK-SSC shall be 25 MHz when SSC is off and 24.875 M to 25 MHz (0 to 0.5% modulation) when it is on.
- the frequency modulation circuit 110 includes a multiphase clock generation circuit 111, a modulation control unit 112, a phase subdivision unit 113, a clock selection unit 114, and a frequency divider circuit 115. ing.
- the multi-phase clock generation circuit 111 generates a multi-phase clock PH [1:20] of 250 MHz x 20 phases (in increments of 200 ps) based on the input reference clock REFCK and outputs it to the phase subdivision unit 113 It becomes.
- the modulation control unit 112 includes a phase control signal PICTRL [1: 3] for controlling the phase subdivision unit 113 and a clock selection signal PHS EL [1: 20] is generated according to the selection signal SSC-EN.
- the modulation control unit 112 performs this operation in synchronization with the clock signal CK-SSC output from the frequency dividing circuit 115.
- the phase control signal PICTRL [1: 3] with the pattern shown in Code 1 to Code 8 in Fig. 3 is repeatedly switched and output.
- the modulation control unit 112 when SSC is on, the modulation control unit 112 performs T mode, T + ⁇ mode, ⁇ + 2 ⁇ mode, ⁇ + 3 ⁇ mode, ⁇ + 4 ⁇ mode, T + 5 ⁇ mode, ⁇ + 6 ⁇ mode, ⁇ ⁇ Repeatedly outputs the clock selection signal PHSEL [1: 20] corresponding to each operation mode of + 7 ⁇ mode and T + 8 ⁇ mode.
- the modulation control unit 112 is designed by, for example, RTL, and is a full digital circuit in which all circuits are configured by digital circuits.
- the phase subdivision unit 113 is a modulation control unit! ⁇ ! Phase control signal output from ⁇ ! ⁇ ! ⁇ :
- the phase of the multi-phase clock PH [1:20] is shifted to generate the 20-phase clock signal PHI [1:20] and output it to the clock selector 114.
- the phase subdivision unit 113 can be configured by, for example, the circuit shown in FIG.
- This circuit is a typical current difference consisting of resistors R1 and R2, two differential switches (a pair of NMOS transistors MN1 and MN2, and a pair of NMOS transistors MN3 and MN4) and current sources II and 12. It is a dynamic phase interpolator.
- This circuit weights the phase by changing the current ratio between current sources II and 12, and outputs the phase between differential inputs A and B to differential output OUT.
- the current sources II and 12 are controlled by PICTRL [1: 3] and NPICTRL [1: 3] so that the sum of the current of the current source II and the current of 12 is always constant.
- NPICTRL [1: 3] is the inverted signal of PICTRL [1: 3]).
- the clock selection unit 114 selects one clock signal from the 20-phase clock signals PHI [1: 20] according to the clock selection signal PHSEL [1:20] output from the modulation control unit 112. However, the clock signal CKSEL is output to the frequency dividing circuit 115.
- the clock selection unit 114 selects a clock signal as follows according to each of the following operation modes (T mode, T + ⁇ mode... (See FIG. 5).
- T mode Always select PH1.
- T + ⁇ mode After selecting PH1 10 times, move the phase to PH2 and select 10 times, move the phase to PH3 and select 10 times.
- In ⁇ + 2 ⁇ mode After selecting PHI 10 times, move the phase to PH3 and select 10 times, then move the phase to PH5 and select 10 times.
- the clock selection unit 114 can be configured by a circuit shown in FIG. 6, for example. This circuit is a typical 20: 1 MUX circuit.
- the frequency dividing circuit 115 divides the clock signal CKSEL by 10 and outputs it to the PLL circuit 120 and the modulation control unit 112 as the clock signal CK-SSC.
- the frequency divider 115 is a frequency divider of 10 configured using D flip-flops.
- the PLL circuit 120 is a third-order charge pump type PLL circuit, and the bandwidth can be switched according to the level of the selection signal SSC—EN.
- the PLL circuit 120 includes a frequency phase comparison circuit 120a (PFD), a charge pump circuit 1201) (figure?), And a low-pass filter 120, as shown in FIG. ( ⁇ ), Voltage-controlled oscillator 120 (10 ⁇ 0), and frequency divider 120e (DIVIDER). Bandwidth switching is performed by changing the resistance value of the resistor element, the capacitance value of the capacitor element, and the charge pump. This is realized by switching the current value of the circuit 120b.
- the frequency phase comparison circuit 120a outputs a signal corresponding to the phase difference between the output clock signal CKOUT and the reference clock signal REF CK to the charge pump circuit 120b.
- the charge pump circuit 120b outputs a signal having a voltage corresponding to the signal output from the frequency phase comparison circuit 120a.
- the current value of the output of the charge pump circuit 120b is switched according to the selection signal SSC-EN.
- Fig. 9 shows the stitching of the dipump current value (CP current value) and VCO gain (gain of voltage controlled oscillation circuit 120d).
- the voltage controlled oscillation circuit 120d is configured to output an output clock signal CKOUT having a frequency corresponding to the voltage output from the low-pass filter 120c to the outside of the clock generation circuit 100 and the frequency dividing circuit 120e.
- the frequency dividing circuit 120e divides the output clock signal CKOUT output from the voltage controlled oscillation circuit 120d and outputs it to the frequency phase comparison circuit 120a. In the present embodiment, the frequency dividing circuit 120e divides the output clock signal CKOUT by 60.
- the frequency modulation circuit 110 receives the input reference clock REFCK (25MHz), performs frequency modulation, and spreads the clock signal CK—SSC to the PLL circuit 120. Output.
- the PLL circuit 120 outputs an output clock signal CKOUT obtained by multiplying the clock signal CK — SSC by 60 ⁇ .
- the selection signal SSC-EN is at the H level
- a frequency-modulated clock signal is output from the frequency modulation circuit 110 as CKOUT
- the frequency modulation is performed ! /, Clock signal is output.
- the modulation control unit 112 repeatedly switches and outputs the phase control signals PICTRL [1: 3] having patterns shown in Code 1 to Code 8 in FIG. Further, the modulation control unit 112 repeatedly outputs the clock selection signal PHSEL [1:20] corresponding to each of the operation modes.
- Modulation control unit! Phase control signal with ⁇ output! ⁇ Jing! ⁇ : According to 3], the phase subdivision section 113 subdivides the multiphase clock PH [1:20] of 250MHz x 20 phases (in 200ps increments) into 160 phases (in 25ps increments). Then, the phase subdivision unit 113 generates a 20-phase clock signal P HI [1:20] and outputs it to the clock selection unit 114.
- the clock selection unit 114 selects and divides the frequency by selecting one clock signal from the power of the 20-phase clock signal output by the phase subdivision unit 113. Output to circuit 1 15
- the clock generation circuit 100 includes T mode, T + ⁇ mode, ⁇ + 2 ⁇ mode, ⁇ + 3 ⁇ mode, ⁇ + 4 ⁇ mode, ⁇ + 5 ⁇ mode, ⁇ + 6 ⁇ mode, ⁇ + 7 ⁇ mode, ⁇ + 8 ⁇ mode, ⁇ + 7 ⁇ mode, ⁇ + 6 ⁇ mode, T + 5 ⁇ mode, ⁇ + 4 ⁇ mode, ⁇ + 3 ⁇ mode, ⁇ + 2 ⁇ mode, T + ⁇ mode, T mode Change the state and repeat this indefinitely.
- T is the output clock signal period of 40 ns
- ⁇ is the period variation of 25 ps, which is equivalent to 0.00625% of 40 ns.
- value-th equivalent to 0.5 0/0 of 200ps force S40ns.
- the frequency dividing circuit 115 divides the output of the clock selection unit 114 and outputs a clock signal CK_SSC (modulated clock). In this way, by dividing the frequency by the frequency dividing circuit 115, a fine modulation factor of -0.5% can be realized even if the phase shift of one time is a relatively large value of 200 ps.
- the clock selection signal PHSEL [1:20] corresponding to the mode is output.
- phase subdivision unit 113 and the clock selection unit 114 always operate in the T mode, and the clock signal CK_SSC output from the frequency modulation circuit 110 is always 25 MHz as shown in FIG. Constant (modulation rate: 0%). That is, the output clock signal CKOUT output from the PLL circuit 120 is a constant 1.5 GHz.
- an LSI designer or a set designer selects SSC on Z off as the selection signal. With or without switching, the presence or absence of the SSC function can be selected freely. Therefore, for example, when the connection partner (reception side) of a set such as an LSI or DVD player equipped with the clock generation circuit 100 on the transmission side does not support SSC, and the connectivity is poor when SSC is on Can be used by switching off SSC.
- verification of LSIs and sets with and without frequency modulation can be realized only with LSI internal circuits. Therefore, it is possible to perform verification at a low cost and with efficiency without the need to provide an external circuit for verification.
- the characteristics of the PLL circuit 120 can be adjusted depending on whether the frequency modulation is strong or not, so that the voltage-controlled oscillation circuit in the PLL circuit 120 can be adjusted. 120d accumulated jitter can be reduced. That is, in this embodiment, it becomes possible to achieve both improvement in connectivity when SSC is on and reduction of accumulated jitter when SSC is off.
- a register unit that can read and write information from the outside and a register reference unit that reads the information in the register unit and generates and outputs the selection signal SSC-EN are added to the clock generation circuit 100. May be. According to this configuration, for example, SSC on / off can be switched by rewriting the contents of the register with software.
- the selection signal SSC-EN may be fixed to a predetermined logic level by holding a predetermined value in the register unit. This makes it possible to provide the same circuit as an SSC dedicated clock generation circuit or a clock generation circuit without an SSC function.
- the SSC may be switched on in terms of force.
- a lock detection signal (L OCKDET: for example, locked when H, unlocked when L) indicating whether or not the PLL is locked is output from the PLL circuit 120
- An AND circuit that inputs the mouth detection signal and the selection signal SSC-EN input from the outside is provided, and the output of the AND circuit is input to the frequency modulation circuit 110 as a signal for SSC on / off switching control.
- the PICTRL [1: 3] signal is a 3-bit signal and frequency modulation of 8 gradations is realized is described.
- phase subdivision section 113 When the phase subdivision section 113 is differentially operated and the clock selection section 114 is single operation, a differential single conversion circuit is provided between the phase subdivision section 113 and the clock selection section 114. (If the phase subdivision section 113 and the clock selection section 114 are both in differential operation or single operation, a conversion circuit is required.)
- FIG. 15 is a block diagram showing a configuration of the clock generation circuit 200 according to Embodiment 2 of the present invention.
- the clock generation circuit 200 includes a PLL circuit 120, a frequency modulation circuit 210, and a frequency modulation detection circuit 220.
- the clock generation circuit 200 includes a terminal to which the reference clock signal REFCK is input, a terminal to output the output clock signal CKOUT, and a terminal to which the reset signal RESET is input.
- the frequency modulation circuit 210 generates a clock signal based on the input reference clock REFCK and outputs it as the clock signal CK-SSC.
- the frequency modulation circuit 210 is a circuit of a separate chip from the PLL circuit 120 and the frequency modulation detection circuit 220, and is a digital frequency modulation circuit. Further, the clock signal generated by the frequency modulation circuit 210 may be frequency modulated or not.
- the frequency modulation detection circuit 220 detects whether or not the clock signal CK-SSC generated by the frequency modulation circuit 210 is frequency-modulated. If the clock signal CK-SSC is frequency-modulated, The H level selection signal SSC_EN is output, and when the clock signal CK_SSC is frequency-modulated, the L level selection signal SSC-EN is output.
- FIG. 16 is a block diagram showing a configuration example of the frequency modulation detection circuit 220.
- the detection circuit 220 includes flip-flops 221a to 221e, flip-flops 222a to 222e, AND circuits 223a to 223c, an OR circuit 224, and a flip-flop 225.
- the frequency modulation detection circuit 220 receives the clock signal CK—SSC, the reference clock signal REFCK, and the reset signal RESET.
- flip-flop 221a and flip-flop 222c are flip-flops with a set function, and the other flip-flops are flip-flops with a reset function.
- the flip-flops 221a to 221e constitute a shift register (REFCK shift register) that uses the reference clock signal REFCK as the CK input of the flip-flop (D flip-flop). Further, the flip-flops 222a to 222e constitute a shift register (CK_SSC shift register) that uses the clock signal CK-SSC as the CK input of the flip-flop (D flip-flop).
- the overall operation of the clock generation circuit 200 is to receive the clock signal CK—SSC output from the frequency modulation circuit 210 and output the clock signal CK—SSC to the PLL circuit 120 and the frequency modulation detection circuit 220.
- the PLL circuit 120 clocks up the clock signal CK—SSC and outputs it as CKOUT.
- the frequency modulation detection circuit 220 detects whether or not the clock signal CK-SSC is strongly modulated, and the detection result is received by the PLL circuit 120. When the modulation is strong, the bandwidth of the PLL circuit 120 is decreased. When the modulation is significant, the bandwidth of the PLL circuit 120 is increased.
- the reset signal RESET is at the H level.
- the REFCK shift register only the Q output of the first flip-flop 221a from the left as the initial value is H level, and in the CK-SSC shift register, the initial value of the third flip-flop 222c from the left is set as the initial value.
- Q output H level At that time, the other flip-flops are in the reset state and the Q output is fixed to the L level.
- the bandwidth of the PLL circuit 120 is adjusted in accordance with the selection signal SSC—EN. Therefore, the characteristics of the PLL circuit 120 can be adjusted according to whether or not the frequency modulation is applied to the clock signal CK-SSC output from the frequency modulation circuit 210, and jitter can be reduced.
- the frequency modulation detection circuit 220 described above is a simple configuration configured by a full digital system that performs signal processing at a logic level, so that it can be realized with low power and a small area, and process migration can be facilitated.
- the clock generation circuit according to the present invention can easily switch on / off of the SSC function, and even if the SSC function is turned on / off, the connectivity does not deteriorate due to an increase in jitter. If it can be made V, it is effective as a clock generation circuit having a spread spectrum clocking function.
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JP2007553847A JP4510097B2 (ja) | 2006-01-11 | 2006-11-30 | クロック生成回路 |
US12/095,094 US7825707B2 (en) | 2006-01-11 | 2006-11-30 | Clock generation circuit having a spread spectrum clocking function |
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JP2006003513 | 2006-01-11 | ||
JP2006-003513 | 2006-01-11 |
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JP (1) | JP4510097B2 (ja) |
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WO2009057289A1 (ja) * | 2007-11-02 | 2009-05-07 | Panasonic Corporation | スペクトラム拡散クロック発生装置 |
JP2011061705A (ja) * | 2009-09-14 | 2011-03-24 | Brother Industries Ltd | スペクトラム拡散クロックの周波数レベル検出方法及びスペクトラム拡散クロックの周波数レベル検出装置 |
JP2012119737A (ja) * | 2010-11-29 | 2012-06-21 | Toshiba Corp | 無線通信装置 |
JP2015115633A (ja) * | 2013-12-09 | 2015-06-22 | 株式会社メガチップス | クロック生成回路 |
US9832336B2 (en) | 2010-10-29 | 2017-11-28 | Brother Kogyo Kabushiki Kaisha | Image-reading device that reads images by using spread-spectrum clock |
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US8711983B2 (en) * | 2010-10-29 | 2014-04-29 | Texas Instruments Incorporated | Phase locking loop |
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US8724674B2 (en) * | 2012-07-27 | 2014-05-13 | Ati Technologies Ulc | Disabling spread-spectrum clock signal generation |
US9405314B1 (en) * | 2014-05-02 | 2016-08-02 | Cadence Design Systems, Inc. | System and method for synchronously adjusted delay and distortion mitigated recovery of signals |
TWI691187B (zh) * | 2014-08-21 | 2020-04-11 | 日商新力股份有限公司 | 信號處理裝置及方法 |
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US10241536B2 (en) | 2016-12-01 | 2019-03-26 | Intel Corporation | Method, apparatus and system for dynamic clock frequency control on a bus |
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- 2006-11-30 CN CNA2006800509123A patent/CN101356735A/zh active Pending
- 2006-11-30 JP JP2007553847A patent/JP4510097B2/ja active Active
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WO2009057289A1 (ja) * | 2007-11-02 | 2009-05-07 | Panasonic Corporation | スペクトラム拡散クロック発生装置 |
US8085101B2 (en) | 2007-11-02 | 2011-12-27 | Panasonic Corporation | Spread spectrum clock generation device |
JP5022445B2 (ja) * | 2007-11-02 | 2012-09-12 | パナソニック株式会社 | スペクトラム拡散クロック発生装置 |
JP2011061705A (ja) * | 2009-09-14 | 2011-03-24 | Brother Industries Ltd | スペクトラム拡散クロックの周波数レベル検出方法及びスペクトラム拡散クロックの周波数レベル検出装置 |
US8634446B2 (en) | 2009-09-14 | 2014-01-21 | Brother Kogyo Kabushiki Kaisha | Frequency level detecting method |
US9832336B2 (en) | 2010-10-29 | 2017-11-28 | Brother Kogyo Kabushiki Kaisha | Image-reading device that reads images by using spread-spectrum clock |
JP2012119737A (ja) * | 2010-11-29 | 2012-06-21 | Toshiba Corp | 無線通信装置 |
US9071252B2 (en) | 2010-11-29 | 2015-06-30 | Kabushiki Kaisha Toshiba | Radio communication apparatus |
JP2015115633A (ja) * | 2013-12-09 | 2015-06-22 | 株式会社メガチップス | クロック生成回路 |
Also Published As
Publication number | Publication date |
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US20090284297A1 (en) | 2009-11-19 |
CN101356735A (zh) | 2009-01-28 |
JPWO2007080719A1 (ja) | 2009-06-11 |
JP4510097B2 (ja) | 2010-07-21 |
US7825707B2 (en) | 2010-11-02 |
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