Signal generating circuit

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Quick Facts

Patent No.: US 7,696,803
App. No.: 12/292,618
Granted: Apr 13, 2010
Kind: B2

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Abstract

A signal generating circuit includes an input stage delay circuit which can switch a state of outputting a reference clock and a state of outputting a signal delaying the reference clock by a first time which is shorter than one cycle of the reference clock, a control section including a gate circuit holding the output of the input stage delay circuit for a second time which is shorter than one cycle of the reference clock from a point at which the output of the input stage delay circuit is changed to output a signal corresponding to the output of the gate circuit, and an output stage delay circuit outputting a signal delaying the output signal of the control section by the second time, in which the input stage delay circuit switches an output state in response to change of the output signal of the control section.

Claims (61)

1. A signal generating circuit, comprising:

an input stage delay circuit which can switch a state of outputting a reference clock and a state of outputting a signal delaying the reference clock by a first time which is shorter than one cycle of the reference clock;

a control section including a gate circuit holding the output of the input stage delay circuit for a second time which is shorter than one cycle of the reference clock from a point at which the output of the input stage delay circuit is changed to output a signal corresponding to the output of the gate circuit; and

an output stage delay circuit outputting a signal delaying the output signal of the control section by the second time,

wherein the input stage delay circuit switches an output state in response to change of the output signal of the control section.

2. The signal generating circuit according to claim 1 , wherein

the input stage delay circuit includes delay elements which can provide delay of the first time, and

the output stage delay circuit includes delay elements which can provide delay of the second time.

3. The signal generating circuit according to claim 2 , wherein the input stage delay circuit and the output stage delay circuit each includes (n−1) delay elements, each of which can provide delays of 1/n, 2/n, . . . , (n−2)/n, (n−1)/n times when the second time corresponds to m/n (m, n are natural numbers, m<n, irreducible fraction) time with respect to one cycle of the reference clock.

4. The signal generating circuit according to claim 3 , wherein the output stage delay circuit selects a delay element which can provide the delay of the m/n time from among the (n−1) delay elements.

5. The signal generating circuit according to claim 4 , wherein the input stage delay circuit selects a state of outputting the reference clock at first and then selects a delay element capable of providing a delay time equal to the delay element selected at the output stage delay circuit when the output state is switched in response to the change of the output signal of the control section for the first time.

6. The signal generating circuit according to claim 1 , wherein the gate circuit directly outputs the output of the input stage delay circuit without holding the output of the input stage delay circuit when the output of the input stage delay circuit, the output of the control section, and the output of the output stage delay circuit all match with each other.

7. The signal generating circuit according to claim 2 , wherein the gate circuit directly outputs the output of the input stage delay circuit without holding the output of the input stage delay circuit when the output of the input stage delay circuit, the output of the control section, and the output of the output stage delay circuit all match with each other.

8. The signal generating circuit according to claim 3 , wherein the gate circuit directly outputs the output of the input stage delay circuit without holding the output of the input stage delay circuit when the output of the input stage delay circuit, the output of the control section, and the output of the output stage delay circuit all match with each other.

9. The signal generating circuit according to claim 4 , wherein the gate circuit directly outputs the output of the input stage delay circuit without holding the output of the input stage delay circuit when the output of the input stage delay circuit, the output of the control section, and the output of the output stage delay circuit all match with each other.

10. The signal generating circuit according to claim 5 , wherein the gate circuit directly outputs the output of the input stage delay circuit without holding the output of the input stage delay circuit when the output of the input stage delay circuit, the output of the control section, and the output of the output stage delay circuit all match with each other.

11. The signal generating circuit according to claim 1 , wherein

the control section comprises:

a counter counting a number of pulses output from the gate circuit; and

a cycle compare register storing a cycle set value compared with a count value of the counter, and