WO2008065869A1 - Circuit de division de fréquence de signal d'horloge et procédé de division de fréquence de signal d'horloge - Google Patents
Circuit de division de fréquence de signal d'horloge et procédé de division de fréquence de signal d'horloge Download PDFInfo
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- WO2008065869A1 WO2008065869A1 PCT/JP2007/071790 JP2007071790W WO2008065869A1 WO 2008065869 A1 WO2008065869 A1 WO 2008065869A1 JP 2007071790 W JP2007071790 W JP 2007071790W WO 2008065869 A1 WO2008065869 A1 WO 2008065869A1
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K23/00—Pulse counters comprising counting chains; Frequency dividers comprising counting chains
- H03K23/40—Gating or clocking signals applied to all stages, i.e. synchronous counters
- H03K23/48—Gating or clocking signals applied to all stages, i.e. synchronous counters with a base or radix other than a power of two
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- 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
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K23/00—Pulse counters comprising counting chains; Frequency dividers comprising counting chains
- H03K23/64—Pulse counters comprising counting chains; Frequency dividers comprising counting chains with a base or radix other than a power of two
- H03K23/66—Pulse counters comprising counting chains; Frequency dividers comprising counting chains with a base or radix other than a power of two with a variable counting base, e.g. by presetting or by adding or suppressing pulses
- H03K23/667—Pulse counters comprising counting chains; Frequency dividers comprising counting chains with a base or radix other than a power of two with a variable counting base, e.g. by presetting or by adding or suppressing pulses by switching the base during a counting cycle
Definitions
- the present invention relates to a clock signal frequency dividing circuit and a clock signal frequency dividing method for realizing an arbitrary rational frequency division of a clock with low power, low area, and low design cost.
- a clock frequency dividing circuit that divides and generates a clock signal having a lower frequency from a clock signal having a certain frequency
- the frequency division ratio that is, the frequency of the clock signal before frequency division and the frequency of the clock signal after frequency division
- a frequency dividing circuit (integer frequency dividing circuit) of specific force Sl / M (M is an integer) with frequency can be easily realized by using a counter circuit.
- the value that sets the numerator of the division ratio (the value of N in the division ratio N / M) is cumulatively added every cycle of the input clock signal, If the addition result is larger than the value that sets the denominator of the division ratio (the value of M at the division ratio N / M), the operation is performed to subtract M from the addition result, and the addition result is
- the rational number is divided by appropriately thinning out the input clock signal.
- Patent Document 3 a clock generation circuit using a phase interpolator has been proposed (for example, Patent Document 3).
- Patent Document 3 an edge can be generated at a timing other than the edge of the input clock signal by the phase interpolation circuit, so that a rational frequency divided clock signal with a constant cycle time can be generated.
- Patent Document 1 Japanese Patent Laid-Open No. 2005-45507
- Patent Document 2 JP-A-2006-148807
- Patent Document 3 JP-A-2002-57578
- the clock divider circuit described in Patent Document 1 or Patent Document 2 is provided with a clock for an input clock signal. Since the frequency division is realized by selectively decimating the Nores, the timing of the Nores output of the divided clock signal is limited to that of the input clock signal.
- FIG. 10 shows an example of clock division by the above technique, and shows an output clock signal obtained by dividing the input clock signal (8/8) by a division ratio of 7/8 to 1/8.
- the phase interpolation circuit is a relatively low frequency input clock signal.
- a large capacity is required, so there is a problem that power consumption and layout area are large and noise is weak.
- a dedicated design is required for the analog circuit, and the design / verification cost is high.
- An object of the present invention is to solve the above-described problem, and the minimum cycle time of the divided clock signal in which the variation in the cycle time of the divided clock signal is small is increased according to the division ratio.
- the purpose is to provide a clock signal frequency dividing circuit and a clock signal frequency dividing method with a low design cost and a low verification cost.
- a clock signal divider circuit includes a clock signal divider circuit in which a division ratio is defined by N / M, which is a ratio of two integers N and M.
- a clock selection circuit that selects one of the power to output the clock signal as it is, the power to invert and output the input clock signal, and no output of the input clock signal, and the clock selection circuit Control means for generating a control signal for controlling the selection, and the control unit in the first half controls the selection of the clock selection circuit for each cycle of the input clock signal.
- the clock signal dividing method of the present invention is a clock signal dividing method for outputting a clock signal defined by N / M, which is a ratio of two integers N and M.
- the selection of the clock selection circuit is controlled for each cycle of the input clock signal.
- the ideal ability to output the input clock signal as it is, the inverted output of the input clock signal, or no output of the input clock signal is ideal.
- the present invention is configured only by a digital logic circuit, and the input clock signal is output as it is, the power to invert the input clock signal and output, the input clock signal is not output, Since it is sufficient to provide a function for selecting one of the above, it is possible to realize a rational frequency divider circuit that has a low power consumption and a low layout area and a low verification cost.
- the clock signal divider circuit includes a clock selection control circuit 100 and an output clock selection circuit 200, and the input clock signal is divided by a frequency division ratio N / M (M , N is an integer) and output as an output clock signal.
- the clock selection control circuit 100 operates at the timing of the input clock signal, refers to the division ratio setting signals M—N, — N, and N, and outputs the clock phase control signal 101 and the clock output.
- a control signal 102 is generated for each cycle of the input clock signal.
- the clock selection control circuit 100 includes a phase calculation circuit 105, a clock output determination circuit 106, and a clock phase determination circuit 107.
- the phase calculation circuit 105 calculates the phase of an ideal frequency-divided clock signal with a division ratio of N / M and a constant cycle time with respect to the input clock signal for each input clock signal. To calculate.
- the clock output determination circuit 106 refers to the phase calculation result calculated by the phase calculation circuit 105 to determine whether or not to output the input clock signal to the output clock signal, and outputs it as the clock output control signal 102 To do.
- the clock output determination circuit 106 indicates that when the phase calculation result indicates less than one cycle of the input clock signal! /, The clock selection circuit 200 converts the input clock signal into the output clock signal. A control value that is controlled to be output is output to the clock output control signal 102. When the phase calculation result indicates one or more cycles of the input clock signal, the clock output judgment circuit 106 sets a control value for controlling the clock selection circuit 200 so that the input clock signal is not output to the output clock signal. The clock output control signal 102 is output.
- the clock phase determination circuit 107 refers to an ideal divided clock signal phase with respect to the input clock signal calculated by the phase calculation circuit 105, and outputs an output clock signal when the input clock signal is output as it is. Of the phase and the phase of the output clock signal when the input clock signal is inverted and output as it is, determine the closer to the ideal phase of the divided clock signal and determine the more ideal division. Select the clock closer to the phase of the peripheral clock signal The control value selected by the circuit 200 is output to the clock phase control signal 101.
- the clock phase determination circuit 107 when the phase calculation result indicates less than 0.5 cycle of the input clock signal, the clock phase determination circuit 107 outputs the input clock signal to the output clock signal as it is.
- the control value to be controlled is output to the clock phase control signal 101.
- the clock phase determination circuit 107 controls the clock selection circuit 200 to invert the input clock signal and output it as the output clock signal when the phase calculation result indicates 0.5 or more cycles of the input clock signal.
- the control value to be output is output to the clock phase control signal 101.
- the clock selection circuit 200 Based on the output clock control signal given by the clock phase control signal 101 and the clock output control signal 102, the clock selection circuit 200 outputs the input clock signal as it is, or inverts and outputs the input clock signal. Select whether to output power or not to output the input clock signal.
- the clock selection circuit 200 includes an AND circuit 210, an inverter circuit 211, and a selector circuit 212.
- the AND circuit 210 masks the input clock signal based on the clock output control signal 102. More specifically, the AND circuit 210 masks the input clock signal when the value of the clock output control signal 102 is 0. The AND circuit 210 does not mask the input clock signal when the value of the clock output control signal 102 is 1.
- the inverter circuit 211 inverts the input clock signal.
- the selector circuit 212 selects based on the clock phase control signal 101 whether to output the input clock signal as it is to the output clock signal or whether to output a signal obtained by inverting the input clock signal to the output clock signal.
- the selector circuit 212 outputs the input clock signal as it is to the output clock signal when the value of the clock phase control signal 101 is 0.
- the selector circuit 212 outputs a signal obtained by inverting the input clock signal to the output clock signal.
- the clock selection circuit 200 has the clock phase control signal 101 value 0 based on the clock phase control signal 101 and the clock output control signal 102, and the clock output control If the value of signal 102 is 1, the input clock signal is output as is as the output clock signal.
- the clock selection circuit 200 inverts the input clock signal and outputs it as an output clock signal.
- the clock selection circuit 200 does not output the clock signal as the output clock signal by masking the input clock signal.
- the clock selection control circuit 100 receives a division ratio setting signal M—N, — N, N, and receives a clock phase control signal 101 that is a control signal of the clock selection circuit 200 in each cycle of the input clock signal. And a clock output control signal 102 are generated.
- the phase calculation circuit 105 of the clock selection circuit 100 includes a selector circuit 114, an adder 110, and flip-flop circuits 120 and 121.
- the clock output determination circuit 106 of the clock selection control circuit 100 includes a magnitude comparator 112.
- the clock phase determination circuit 107 of the clock selection control circuit 100 includes a double multiplier 115 and a magnitude comparator 113.
- the flip-flop circuits 120 and 121 of the phase calculation circuit 105 operate based on the timing of the rising edge of the input clock signal (the input clock signal is not shown in FIG. 2).
- the input clock signal, the output clock signal, and the phase calculation value 103 that is the output of the adder 110, the clock phase control signal 101 that is the output of the magnitude comparator 113, and the output of the magnitude comparator 112 are shown.
- a clock output control signal 102 is illustrated.
- an ideal frequency-divided clock signal with a division ratio of 5/8 and a constant cycle time and its phase with respect to the input clock signal are shown.
- Double multiplier 1 15 doubles the value of phase calculation value 103 and outputs the result to magnitude comparator 113.
- the magnitude comparator 113 refers to the value obtained by doubling the value of the phase calculation value 103 and the comparison result of N. If the value twice the phase calculation value 103 is N or more, the magnitude comparator 113 , Twice the calculated phase value of 103 If the value is less than N, the value 0 is output to the clock phase control signal 101.
- the value of the clock phase control signal 101 is zero.
- the magnitude comparator 112 refers to the phase calculation value 103 and the comparison result of N, and if the phase calculation value 103 is equal to or greater than N, the value 0 is set. Output to clock output control signal 102. In cycle 0, the value of the clock output control signal 102 is 1.
- the clock selection circuit 200 outputs the input clock signal as it is as the output clock signal. This corresponds to the fact that the phase of the ideal divided clock signal is closer than the case where the input clock signal is output as it is as the output clock signal and the 1S input clock signal is inverted and output.
- flip-flop 121 holds that the result of magnitude comparator 1 12 in cycle 0, that is, that phase calculation value 103 was less than N.
- the selector circuit 114 refers to the result of the magnitude comparator 112 of the previous cycle held in the flip-flop 121, and selects the input—N if the phase calculation value 103 is equal to or greater than N. If the calculated value 103 is less than N, select the input M—N.
- the clock selection circuit 200 inverts the input clock signal and outputs it as an output clock signal. This corresponds to the fact that the input clock signal is output to the output clock signal as it is, and the force S for inverting and outputting the input clock signal is closer to the ideal divided clock signal phase.
- flip-flop 121 holds that the value of phase calculation value 103 in cycle 2 is N or more.
- the clock selection circuit 200 outputs the input clock signal as it is as the output clock signal. This corresponds to the fact that it is closer to the phase of the ideal divided clock signal when the input clock signal is directly output to the output clock signal than when the input clock signal is inverted and output.
- the clock selection circuit 200 inverts the input clock signal and outputs it as an output clock signal. This corresponds to the fact that the input clock signal is inverted and output closer to the ideal phase of the divided clock signal than the input clock signal is directly output to the output clock signal.
- the clock selection circuit 200 outputs the input clock signal as it is as the output clock signal. This corresponds to the fact that the input clock signal is directly output to the output clock signal S, and that it is closer to the ideal divided clock signal phase than the inverted input clock signal.
- the clock selection circuit 200 does not output an input clock signal as an output clock signal.
- Flip flop 1
- the magnitude comparator 113 refers to the value obtained by doubling the value of the phase calculation value 103 and the comparison result of N, and since the value twice the phase calculation value 103 is less than N, the clock phase The value of the control signal 101 is zero.
- the magnitude comparator 112 refers to the phase calculation value 103 and the comparison result of N, and since the value of the phase calculation value 103 is less than N, the value of the clock output control signal 102 is 1.
- the clock selection circuit 200 outputs the input clock signal as it is as the output clock signal. This situation is similar to the cycle 0 situation described above. Therefore, after that, the operation from cycle 0 to cycle 7 is repeated.
- the input clock signal is inverted and output as the output clock signal in cycle 1 and cycle 4.
- cycle time from the rise of the output clock signal at cycle 0 to the rise of the output clock signal at cycle 1 is extended to 1.5 cycles of the input clock signal.
- cycle 4 The cycle time until the rising edge of the output clock signal is extended to 1.5 cycles of the input clock signal.
- the minimum cycle time of the divided clock signal is expanded to 1.5 cycles of the input clock signal according to the division ratio. It is possible.
- the maximum cycle time of the divided clock signal is, for example, two cycles of the input clock signal from the rising edge of the output clock signal at the cycle 6 to the rising edge S of the output clock signal at the cycle 0. .
- the minimum cycle time variation of the divided clock signal is 1.5 to 2 cycles of the input clock signal, and the cycle time varies from cycle to cycle. There is a characteristic that is small.
- the clock divider circuit selects any one of the power to output the input clock signal as it is, the power to invert and output the input clock signal, and not to output the input clock signal. In this manner, the clock selection circuit 200 is controlled to generate a divided clock signal. Since the selection control operates to approximate the phase of an ideal divided clock signal with a constant cycle time, the minimum cycle time of the divided clock signal is expanded according to the division ratio. The generation of a rational frequency-divided clock signal with a small variation in cycle time with a large number of opportunities is required.
- the clock selection circuit 200 is composed of only a digital logic circuit, and is capable of outputting the input clock signal as it is, the power of inverting the input clock signal, and not outputting the input clock signal. Since it is sufficient to provide a function for selecting one of the above, there is a feature that power consumption and layout area are small. In addition, since analog circuits do not use circuits that require dedicated design, the design and verification costs are low.
- the clock selection control circuit 100 is not limited to the power used by inputting the division ratio setting signals M—N, —N, and N.
- M and N may be input and MN and N may be generated and used internally.
- the value of the denominator M of the division ratio is 2
- the amount of hardware necessary for realizing the clock signal frequency dividing circuit according to the embodiment can be further reduced.
- 2x2x2x2 32, such as 2 k (k is an integer), a number that is a power of 2 multiple times.
- the frequency dividing circuit includes a clock selection control circuit 150 and an output clock selection circuit 200.
- the output clock selection circuit 200 has the same configuration as that of Embodiment 1 described above, and the same reference numerals are given and detailed description thereof is omitted.
- the clock selection control circuit 150 operates at the timing of the input clock signal, receives the division ratio setting signal 2M-N, and receives the clock selection circuit in each cycle of the input clock signal.
- the clock selection control circuit 150 includes adders 160 and 161, a flip-flop circuit 162, and a NAND element 163.
- the flip-flop circuit 162 operates based on the timing of the rising edge of the input clock signal (in FIG. 4, the illustration of the input clock signal is omitted! /). .
- the addition result is 2 ( k + 1 ) or more, the value 1 is output to the carry output.
- the clock selection control circuit 150 has a configuration in which the phase calculation circuit 105, the clock output determination circuit 106, and the clock phase determination circuit 107 in the clock selection control circuit 100 of the first embodiment are shared. This was made possible by limiting the value of the denominator M of the division ratio to a power of 2. Therefore, there is a feature that the amount of hardware necessary for realizing the clock selection control circuit 150 is small.
- Input clock signal, output clock signal, and phase that is the result output of adder 160 Calculated value (a) 155, phase calculation carry value that is the carry output of adder 160 (a) 153, phase calculation value that is the result output of adder 161 (b) 156, phase calculation that is the carry output of adder 161
- the clock phase control signal 101 that outputs the carry value (b) 154, the phase calculation carry value (a) 153 as it is, and the clock output control signal 102 that is the output of the NAND element 163 are shown.
- the value 0 is output as the phase calculation carry value (a) 153.
- the adder 161 calculates the phase calculation value (a) value 11 of 155 and the value of the division ratio setting signal to be input.
- the value of 02 is 1. Therefore, the clock selection circuit 200 outputs the input clock signal as it is as the output clock signal.
- flip-flop 162 holds value 6 of phase calculation value (b) 1 56 in cycle 0.
- the clock selection circuit 200 inverts the input clock signal and outputs it as an output clock signal.
- flip-flop 162 holds the value 12 of phase calculation value (b) 1 56 in cycle 1.
- the value 1 is output as the phase calculation carry value (b) 154.
- the clock selection circuit 200 does not output an input clock signal as an output clock signal.
- flip-flop 162 holds value 2 of phase calculation value (b) 1 56 in cycle 2.
- Phase calculation carry value (b) 1 is output as 54 respectively.
- the clock selection circuit 200 outputs the input clock signal as it is as the output clock signal.
- phase calculation value (a) l 55 is 3
- the value of phase calculation carry value (a) l 5 3 is 1
- the value of phase calculation value (b) l 56 is 14
- Phase calculation carry value (b) The value of 54 is 0. Therefore, in cycle 4, the value of the clock phase control signal 101 is 1, and the value of the clock output control signal 102 is 1.
- the clock selection circuit 200 inverts the input clock signal and outputs it as an output clock signal.
- phase calculation value (a) l 55 is 15
- the value of phase calculation carry value (a) l 53 is 0,
- the value of phase calculation value (b) 156 is 10
- the phase calculation Carry value (b) The value of 154 is 1. Therefore, in cycle 6, the value of the clock phase control signal 101 is 0, and the value of the clock output control signal 102 is 1.
- the clock selection circuit 200 outputs the input clock signal as it is as an output clock signal.
- phase calculation value (a) 155 is 5
- the value of phase calculation carry value (a) l 5 3 is 1
- the value of phase calculation value (b) 156 is 0,
- the phase calculation Carry value (b) The value of 54 is 1. Therefore, in cycle 7, the value of the clock phase control signal 101 is 1, and the value of the clock output control signal 102 is 0.
- the clock selection circuit 200 does not output an input clock signal as an output clock signal.
- flip-flop 162 holds the value 0 of phase calculation value (b) l 56 in cycle 7.
- the value of the clock phase control signal 101 is 0, and the value of the clock output control signal 102 is 1.
- the clock selection circuit 200 outputs the input clock signal as it is as the output clock signal. This situation is similar to the cycle 0 situation described above. Therefore, after this, the operation from cycle 0 to cycle 7 is repeated.
- the divided clock signal output from the divider circuit according to the second embodiment is the same as the divided clock signal output from the divider circuit according to the first embodiment.
- the peripheral circuit outputs the input clock signal as it is.
- the divided clock signal is generated by controlling the clock selection circuit 200 so as to select whether the signal is inverted and output or whether the input clock signal is not output.
- the selection control described above operates so as to approximate the phase of an ideal frequency-divided clock signal with a constant cycle time, so that the minimum cycle time of the frequency-divided clock signal is expanded according to the frequency division ratio. Therefore, it is possible to generate a rational frequency division clock signal with a large variation in cycle time.
- the clock selection circuit is controlled by limiting the value of the denominator M of the division ratio to a power of 2 in the two integers N and M that define the division ratio N / M. Therefore, it is possible to reduce the amount of hardware necessary for realizing the clock selection control circuit to be realized, and therefore, it is possible to realize a rational clock signal frequency dividing circuit with smaller power consumption and layout area.
- the clock selection control circuit 150 is used by inputting the division ratio setting signal 2M-N.
- the present invention is not limited to this. For example, you can enter M and N to generate and use 2M N inside! /.
- FIG. 6 is a configuration diagram illustrating a clock selection circuit 300 according to the third embodiment.
- the clock selection circuit 300 includes a selection control signal conversion circuit 350, AND elements 310 and 311, an OR element 312, an inverter element 313, flip-flop circuits 314 and 315, Consists of
- the selection control signal conversion circuit 350 includes AND elements 351 and 352, an inverter 353, and a force, and generates a clock phase control signal 101 and a clock output control signal 102 generated by the clock selection control circuit. These are converted into a clock output control signal (p) 301 and a clock output control signal (n) 302, respectively, so as to be suitable for use in the configuration of the clock selection circuit 300.
- the flip-flop circuit 314 latches the clock output control signal (P) 301 at the falling timing of the input clock signal, and outputs it as the clock output control signal (p) 303.
- the flip-flop circuit 315 latches the clock output control signal (p) 302 at the rising timing of the input clock signal and outputs it as the clock output control signal (p) 304.
- the AND element 310 masks the input clock signal based on the clock output control signal (p) 303. Specifically, the AND element 310 masks the input clock signal when the value of the clock output control signal 303 is 0. When the value of the clock output control signal 303 is 1, the input clock signal is not masked.
- the inverter circuit 313 inverts the input clock signal.
- the AND element 311 masks the signal obtained by inverting the input clock signal based on the clock output control signal (n) 304.
- the OR element 312 joins the input clock signal that passes through the AND element 310 and the inverted signal of the input clock signal that passes through the AND element 311 and outputs it as an output clock signal.
- Input clock signal, output clock signal, clock phase control signal 101 that is output of clock selection control circuit, clock output control signal 102, clock output control signal ( ⁇ ) 303 that is output of flip-flop circuit 314, flip-flop A clock output control signal ( ⁇ ) 304 that is an output of the clock circuit 315 is illustrated.
- the clock phase control signal 101 and the clock output control signal 102 are the same as the control signals generated by the clock selection control circuit 100 according to the first embodiment or the clock selection control circuit 150 according to the second embodiment. Detailed description is omitted.
- the selection control signal conversion circuit 350 outputs the input clock signal as it is from the clock phase control signal 101 and the clock output control signal 102 generated by the clock selection control circuit, and inverts and outputs the input clock signal.
- the output is converted into a clock output control signal ( ⁇ ) 301 and a clock output control signal ( ⁇ ) 302 so as to select whether the input clock signal is not output or not. That is, the selection control signal conversion circuit 350, when outputting the input clock signal as it is, disables the mask function of the AND element 310 and enables the mask function of the AND element 311 to enable the clock output control signal ( p) Output value 1 as 301 and clock output control signal (n) Output value 0 as 302.
- the selection control signal conversion circuit 350 When the input clock signal is inverted and output, in order to enable the mask function of the AND element 310 and disable the mask function of the AND element 311, the selection control signal conversion circuit 350 generates a clock output control signal (p) A value 0 is output as 301, and a value 1 is output as the clock output control signal (n) 302. Entering When the lock signal is not output, in order to enable the mask function of the AND element 310 and the mask function of the AND element 311, the selection control signal conversion circuit 350 uses the value 0 and the clock as the clock output control signal (P) 301. Outputs 0 as output control signal (n) 302.
- the flip-flop circuit 314 latches the clock output control signal (P) 301 at the falling timing of the input clock signal and outputs it as the clock output control signal (p) 303, whereby the clock output control signal (P) Has a function of limiting the transition of 303 to the timing when the value of the input clock signal is zero.
- the flip-flop circuit 315 latches the clock output control signal (p) 302 at the timing of the rising edge of the input clock signal, and outputs it as the clock output control signal (p) 304, whereby the clock output control signal (n) 304
- This function has a function to limit the transition to the timing when the value of the input clock signal is 1. The above-described function suppresses the occurrence of glitches in the output clock signal, so that the timing design of the clock selection circuit and the clock selection control circuit can be facilitated.
- an AND element is used as an element for masking an input clock signal or a signal obtained by inverting the input clock signal based on the clock output control signal, and the AND element having the above two masking functions.
- an OR element is used as an element for merging signals passing through, it is not limited to this. Each may be an OR element and an AND element, or a circuit having an equivalent function may be used.
- the clock selection circuit 400 includes an AND element 410, an XOR element 411, an OR element 412, flip-flop circuits 413 and 414, and a selection control signal conversion circuit 450.
- the selection control signal conversion circuit 450 includes AND elements 451 and 453, and an inverter 452, and generates a clock phase control signal 101 and clock output control generated by the clock selection control circuit.
- the signal 102 is converted into a clock output control signal 401 and a clock phase control signal 402, respectively, so as to be suitable for use in the configuration of the clock selection circuit 400.
- the flip-flop circuit 413 latches the clock phase control signal 402 at the rising timing of the input clock signal and outputs it as the clock phase control signal 404.
- the flip-flop circuit 414 latches the clock output control signal 401 at the falling timing of the input clock signal and outputs it as the clock output control signal 403.
- the XOR element 411 controls whether to output the input clock signal as it is or to invert and output the input clock signal.
- the OR element 412 outputs a logical sum of the clock output control signal 403 and the clock phase control signal 404 as a clock output control signal 405.
- the AND element 410 masks the input clock signal or a signal obtained by inverting the input clock signal based on the clock output control signal 405.
- Input clock signal, output clock signal, clock phase control signal 101 that is the output of the clock selection control circuit, clock output control signal 102, clock output control signal 403 that is the output of flip-flop circuit 414, flip-flop circuit 413 The clock phase control signal 404 which is the output of the OR element 412 and the clock output control signal 405 which is the output of the OR element 412 are shown.
- the clock phase control signal 101 and the clock output control signal 102 are the same as the control signals generated by the clock selection control circuit 100 according to the first embodiment or the clock selection control circuit 150 according to the second embodiment. Detailed description is omitted.
- the selection control signal conversion circuit 450 outputs the input clock signal as it is from the clock phase control signal 101 and the clock output control signal 102 generated by the clock selection control circuit, and inverts and outputs the input clock signal. Therefore, it is converted into a clock output control signal 401 and a clock phase control signal 402 so as to select whether the input clock signal is not output or not. That is, when the input clock signal is output as it is, the selection control signal conversion circuit 450 is configured to control the clock output in order to disable the function of inverting the input clock of the XOR element 411 and enable the mask function of the AND element 410.
- the value 1 is output as the signal 401, and the value 0 is output as the clock phase control signal 402.
- the selection control signal conversion circuit 450 When the input clock signal is inverted and output, enable the function to invert the input clock of the XOR element 411, and AND In order to invalidate the mask function of the element 410, the selection control signal conversion circuit 450 outputs the value 0 as the clock output control signal 401 and the value 1 as the clock phase control signal 402, respectively. When the input clock signal is not output, the selection control signal conversion circuit 450 outputs the value 0 as the clock output control signal 401 and the value 0 as the clock phase control signal 402 to enable the mask function of the AND element 410. To do.
- the flip-flop circuit 413 latches the clock phase control signal 402 at the rising timing of the input clock signal and outputs it as the clock phase control signal 404, whereby the transition of the clock output control signal 405 is changed to the input clock signal. This is limited to the timing when the value of the inverted signal is 0.
- the flip-flop circuit 414 latches the clock output control signal 401 at the falling timing of the input clock signal and outputs it as the clock output control signal 403, so that the transition of the clock output control signal 405 is changed to the value of the input clock signal. Limit to 0 timing. Since the functions of the flip-flop circuits 413 and 414 described above suppress the occurrence of glitches in the output clock signal, there is an effect that the timing design of the clock selection circuit and the clock selection control circuit can be facilitated.
- an X OR element is used as an element for controlling the output clock signal as it is or the output power obtained by inverting the input clock signal.
- the present invention is not limited to a force using an AND element as an element for masking an input clock signal or a signal obtained by inverting the input clock signal based on the clock output control signal 405.
- XNOR elements and OR elements may be used for each, or circuits with equivalent functions may be used.
- the control means applies an ideal frequency-divided clock signal having a frequency division ratio of N / M and a constant cycle time to the input clock signal.
- a means for calculating the phase a means for determining whether or not to output the input clock signal to the output clock signal with reference to a result calculated by the means for calculating the phase, and a means for calculating the phase Referring to the calculated result, either the phase of the output clock signal when the input clock signal is output as it is or the phase of the output clock signal when the input clock signal is inverted and output as it is is the ideal It is desirable to have a configuration that includes a means for determining the near / close direction of the divided clock signal.
- the control means includes a storage means, a value stored by the storage means, and a value obtained by subtracting an integer N from twice an integer M that defines the frequency division ratio.
- the storage means stores the addition result of the second adder for each cycle of the input clock, and controls the clock selection circuit from carry signals of the first and second adders. This is a configuration that generates control signals.
- the clock selection circuit includes means for masking the value of the input clock signal to the value 0 or value 1, means for inverting the value of the input clock signal, and input clock signal. It is desirable to provide a selection means for selecting whether the signal is not inverted! /, The signal, or the input clock signal is inverted.
- the clock selection circuit includes means for masking the value of the input clock signal to the value 0 or value 1, and the value of the signal obtained by inverting the value of the input clock signal to the value 0. Or means for combining and outputting the means for masking to the value 1, the output of the means for masking the value of the input clock signal, and the output of the means for masking the value of the signal obtained by inverting the value of the input clock signal. It is good also as a structure provided.
- the clock selection circuit is based on the value of the input control signal! /, Based on the value of the input clock signal or a value V obtained by inverting the value of the input clock signal.
- the minimum cycle time of the divided clock signal in which the variation in the cycle time of the divided clock signal is small has many opportunities to increase according to the division ratio. Design with a small area ⁇ A clock signal divider circuit and clock signal divider method with low verification cost can be provided.
- FIG. 1 is a configuration diagram illustrating a frequency divider circuit according to a first embodiment of the present invention.
- FIG. 2 is a configuration diagram illustrating a clock selection control circuit according to the first embodiment of the present invention.
- FIG. 3 is a timing chart showing an operation of the clock frequency divider circuit in the first exemplary embodiment of the present invention.
- FIG. 4 is a configuration diagram illustrating a clock frequency divider circuit according to a second embodiment of the present invention.
- FIG. 5 is a timing diagram showing an operation of the clock frequency divider circuit in the second embodiment of the present invention.
- Fig. 6 is a configuration diagram showing a clock frequency divider circuit in the third embodiment of the present invention.
- FIG. 7 is a timing chart showing the operation of the clock frequency divider circuit in the third embodiment of the present invention.
- FIG. 8 is a configuration diagram showing a clock frequency dividing circuit according to a fourth embodiment of the present invention.
- FIG. 9 is a timing chart showing the operation of the clock frequency divider circuit in the fourth embodiment of the present invention.
- FIG. 10 is a timing diagram showing an operation example of rational clock frequency division according to a related technique. Explanation of symbols
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- Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Physics & Mathematics (AREA)
- General Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Manipulation Of Pulses (AREA)
- Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
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US12/515,901 US8081017B2 (en) | 2006-11-29 | 2007-11-09 | Clock signal frequency dividing circuit and clock signal frequency dividing method |
JP2008546931A JP5240850B2 (ja) | 2006-11-29 | 2007-11-09 | クロック信号分周回路及びクロック信号分周方法 |
Applications Claiming Priority (2)
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JP2006322410 | 2006-11-29 | ||
JP2006-322410 | 2006-11-29 |
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WO2008065869A1 true WO2008065869A1 (fr) | 2008-06-05 |
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PCT/JP2007/071790 WO2008065869A1 (fr) | 2006-11-29 | 2007-11-09 | Circuit de division de fréquence de signal d'horloge et procédé de division de fréquence de signal d'horloge |
Country Status (3)
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US (1) | US8081017B2 (ja) |
JP (2) | JP5240850B2 (ja) |
WO (1) | WO2008065869A1 (ja) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2009231899A (ja) * | 2008-03-19 | 2009-10-08 | Nec Corp | クロック信号分周回路および方法 |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2008065869A1 (fr) * | 2006-11-29 | 2008-06-05 | Nec Corporation | Circuit de division de fréquence de signal d'horloge et procédé de division de fréquence de signal d'horloge |
WO2009116398A1 (ja) * | 2008-03-17 | 2009-09-24 | 日本電気株式会社 | クロック信号分周回路および方法 |
JP5522050B2 (ja) * | 2008-10-29 | 2014-06-18 | 日本電気株式会社 | クロック分周回路、クロック分配回路、クロック分周方法及びクロック分配方法 |
US8513987B1 (en) * | 2011-01-13 | 2013-08-20 | Sk Hynix Memory Solutions Inc. | Wide frequency range signal generator using a multiphase frequency divider |
KR102110770B1 (ko) * | 2014-02-14 | 2020-05-14 | 삼성전자 주식회사 | 클럭 분주 장치 |
US9214943B1 (en) * | 2014-10-16 | 2015-12-15 | Freescale Semiconductor, Inc. | Fractional frequency divider |
US9628211B1 (en) * | 2015-06-19 | 2017-04-18 | Amazon Technologies, Inc. | Clock generation with non-integer clock dividing ratio |
CN108111163B (zh) * | 2018-02-11 | 2023-08-25 | 深圳市卓越信息技术有限公司 | 一种高速分频器 |
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JP2005045507A (ja) * | 2003-07-28 | 2005-02-17 | Yamaha Corp | 非整数分周器 |
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US4348640A (en) * | 1980-09-25 | 1982-09-07 | Rockwell International Corporation | Divide by three clock divider with symmertical output |
JPS63269620A (ja) * | 1987-04-27 | 1988-11-07 | Canon Inc | 可変分周器 |
US4866741A (en) * | 1987-11-05 | 1989-09-12 | Magnetic Peripherals Inc. | 3/2 Frequency divider |
JPH033517A (ja) * | 1989-05-31 | 1991-01-09 | Matsushita Electric Ind Co Ltd | クロック発生装置 |
US5040197A (en) * | 1990-03-09 | 1991-08-13 | Codex Corp. | Fractional frequency divider for providing a symmetrical output signal |
US5088057A (en) * | 1990-04-05 | 1992-02-11 | At&T Bell Laboratories | Rational rate frequency generator |
JP3415574B2 (ja) | 2000-08-10 | 2003-06-09 | Necエレクトロニクス株式会社 | Pll回路 |
DE60110631T2 (de) * | 2000-11-23 | 2006-01-19 | Koninklijke Philips Electronics N.V. | Takterzeugungsschaltung und integrierte schaltung zur wiedergabe eines audiosignals mit einer solchen takterzeugungsschaltung |
US6879654B2 (en) * | 2003-04-25 | 2005-04-12 | International Business Machines Corporation | Non-integer frequency divider circuit |
JP4371046B2 (ja) * | 2004-11-24 | 2009-11-25 | ソニー株式会社 | クロック分周回路 |
TWI317211B (en) * | 2005-12-27 | 2009-11-11 | Memetics Technology Co Ltd | Configuration and controlling method of fractional-n pll having fractional frequency divider |
WO2008065869A1 (fr) * | 2006-11-29 | 2008-06-05 | Nec Corporation | Circuit de division de fréquence de signal d'horloge et procédé de division de fréquence de signal d'horloge |
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2007
- 2007-11-09 WO PCT/JP2007/071790 patent/WO2008065869A1/ja active Application Filing
- 2007-11-09 JP JP2008546931A patent/JP5240850B2/ja not_active Expired - Fee Related
- 2007-11-09 US US12/515,901 patent/US8081017B2/en not_active Expired - Fee Related
-
2013
- 2013-03-26 JP JP2013064291A patent/JP5494858B2/ja not_active Expired - Fee Related
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JPH09223959A (ja) * | 1996-02-15 | 1997-08-26 | Sony Corp | 分周回路 |
JP2005045507A (ja) * | 2003-07-28 | 2005-02-17 | Yamaha Corp | 非整数分周器 |
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JP2009231899A (ja) * | 2008-03-19 | 2009-10-08 | Nec Corp | クロック信号分周回路および方法 |
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US20100052740A1 (en) | 2010-03-04 |
JP2013176082A (ja) | 2013-09-05 |
US8081017B2 (en) | 2011-12-20 |
JP5240850B2 (ja) | 2013-07-17 |
JP5494858B2 (ja) | 2014-05-21 |
JPWO2008065869A1 (ja) | 2010-03-04 |
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