Signal generation circuit and electronic apparatus
A signal generation circuit includes a phase difference detector configured to detect a phase difference between a certain oscillation signal of a plurality of oscillation signals and a predetermined reference signal; an oscillator to which a plurality of delay elements are connected annularly, the oscillator being configured to generate the plurality of oscillation signals depending on the detected phase difference; a low-speed signal generation circuit configured to generate a low-speed signal having a lower frequency than the oscillation signal; a detection circuit configured to detect a difference between a predetermined reference timing and a timing at which the low-speed signal has changed; a selection unit configured to select the oscillation signal so that the phase difference with respect to the reference signal is close to the detected difference; and an output unit configured to output the generated low-speed signal in synchronization with the selected oscillation signal.
1. A signal generation circuit, comprising:
a phase difference detector configured to detect a phase difference between a certain oscillation signal of a plurality of oscillation signals and a predetermined reference signal;
an oscillator to which a plurality of delay elements are connected annularly, the oscillator being configured to generate the plurality of oscillation signals depending on the detected phase difference;
a low-speed signal generation circuit configured to generate a low-speed signal having a lower frequency than the oscillation signal;
a detection circuit configured to detect a difference between a predetermined reference timing and a timing at which the low-speed signal has changed;
a selection unit configured to select the oscillation signal so that the phase difference with respect to the reference signal is close to the detected difference; and
an output unit configured to externally output the generated low-speed signal in synchronization with the selected oscillation signal.
2. The signal generation circuit according to claim 1 , wherein
the low-speed signal generation circuit is configured to generate the low-speed signal in synchronization with an operation signal that has divided any one of the plurality of oscillation signals.
3. The signal generation circuit according to claim 1 , further comprising
an operation signal generation circuit configured to generate a signal in synchronization with the reference signal as an operation signal, the low-speed signal generation circuit being configured to generate the low-speed signal in synchronization with the operation signal.
4. The signal generation circuit according to claim 1 , wherein
the low-speed signal generation circuit includes
an integrator configured to generate an integration value by integrating an input value in synchronization with a predetermined operation signal, and
a low-speed signal generator configured to generate, as the low-speed signal, a signal that represents whether or not the integration value exceeds a predetermined value representing the reference timing in synchronization with the operation signal, and
the detection circuit is configured to detect a difference between a maximum value of the integration value in a cycle of the low-speed signal and the predetermined value.
5. The signal generation circuit according to claim 1 , further comprising
a phase comparison circuit configured to compare a phase of an input signal and a phase of the output low-speed signal, and to supply the phase difference there between, the low-speed signal generation circuit being configured to generate the low-speed signal based on the supplied phase difference.
6. An electronic apparatus, comprising:
a phase difference detector configured to detect a phase difference between a certain oscillation signal of a plurality of oscillation signals and a predetermined reference signal;
an oscillator to which a plurality of delay elements are connected annularly, the oscillator being configured to generate the plurality of oscillation signals depending on the detected phase difference;
a low-speed signal generation circuit configured to generate a low-speed signal having a lower frequency than the oscillation signal;
a detection circuit configured to detect a difference between a predetermined reference timing and a timing at which the low-speed signal has changed;
a selection unit configured to select the oscillation signal so that the phase difference with respect to the reference signal is close to the detected difference;
an output unit configured to output the generated low-speed signal in synchronization with the selected oscillation signal; and
an operation circuit configured to operate in synchronization with the output low-speed signal from the output unit.
7. The electronic apparatus according to claim 6 , wherein
the low-speed signal generation circuit is configured to generate the low-speed signal in synchronization with an operation signal that has divided any one of the plurality of oscillation signals.
8. The electronic apparatus according to claim 6 , further comprising
an operation signal generation circuit configured to generate a signal in synchronization with the reference signal as an operation signal, the low-speed signal generation circuit being configured to generate the low-speed signal in synchronization with the operation signal.
9. The electronic apparatus according to claim 6 , wherein
the low-speed signal generation circuit includes
an integrator configured to generate an integration value by integrating an input value in synchronization with a predetermined operation signal, and
a low-speed signal generator configured to generate, as the low-speed signal, a signal that represents whether or not the integration value exceeds a predetermined value representing the reference timing in synchronization with the operation signal, and
the detection circuit is configured to detect a difference between a maximum value of the integration value in a cycle of the low-speed signal and the predetermined value.
10. The electronic apparatus according to claim 6 , further comprising
a phase comparison circuit configured to compare a phase of an input signal and a phase of the output low-speed signal, and to supply the phase difference there between, the low-speed signal generation circuit being configured to generate the low-speed signal based on the supplied phase difference.