Delay control circuit and method
View Patent ↗The present invention relates to a delay control circuit and a method of controlling delay of an output signal generating based on an input signal, wherein a plurality of delayed replicas of a reference signal are generated with dedicated time delays with respect to the reference signal and are sampled at a predetermined timing defined by the input signal. One of the delayed replicas is selected based on the output of the sampling means, and the output signal is generated based on the selected replica. Thereby, a predetermined phase relationship can be generated even in cases where no strict phase relation is given between data and reference signal.
1. A delay control circuit for generating, based on a reference signal, a delayed version of an input signal at a predetermined delay, said delay control circuit comprising:
a. signal generating means for producing a plurality of delayed replicas of said reference signal, each of said delayed replicas having respective dedicated time delays with respect to said reference signal;
b. sampling means for sampling said delayed replicas at a predetermined timing defined by said input signal; and
c. selecting means for selecting one of said replicas based on the output of said sampling means and for generating said delayed version based on said selected replica.
2. A circuit according to claim 1 , wherein said selecting means comprises coding means for generating a selection signal based on said output of said sampling means, wherein said selection signal is used to select said one of said replicas.
3. A circuit according to claim 2 , wherein said coding means comprises an input terminal for inputting a delay information indicating a desired delay of said delayed version, and wherein said coding means is adapted to generate said selection signal based on a combined consideration of said output of said sampling means and said delay information.
4. A circuit according to claim 2 , wherein said codings means comprises a plurality of logic gates receiving at their two inputs terminals respective data of sampled replicas with successive values of said dedicated time delays, and wherein said logic gates are adapted to generate an active output signal if different logic values are applied at their input terminals.
5. A circuit according to claim 4 , wherein said selecting means comprise a plurality of switching means each receiving a respective one of said delayed replicas and being controlled by an output signal of a respective one of said logic gates.
6. A circuit according to claim 1 , wherein said sampling means comprises a plurality of flip flop means for sampling the state of said delayed replicas in response to said predetermined timing of said input signal applied at their clock inputs.
7. A circuit according to claim 6 , wherein said predetermined timing corresponds to at least one of a rising edge and a falling edge of said input signal.
8. A circuit according to claim 1 , wherein said input signal is an intermittend strobe signal and said reference signal is a continuous clock signal.
9. A method of controlling delay of an output signal generating based on an input signal, said method comprising the steps of:
a. generating a plurality of delayed replicas of a reference signal, each of said delayed replicas having respective dedicated time delays with respect to said reference signal;
b. sampling said delayed replicas at a predetermined timing defined by said input signal;
c. selecting one of said replicas based on the output of said sampling means; and
d. generating said output signal based on said selected replica.
10. A delay control circuit for generating, based on a reference signal, a delayed version of an input signal at a predetermined delay, said delay control circuit comprising:
signal generating means for producing a plurality of delayed replicas of said reference signal, each of said delayed replicas having respective dedicated time delays with respect to said reference signal;
sampling means for sampling said delayed replicas at a predetermined timing defined by said input signal;
selecting means for selecting one of said replicas based on the output of said sampling means and for generating said delayed version based on said selected replica;
wherein said selecting means comprises coding means for generating a selection signal based on said output of said sampling means, wherein said selection signal is used to select said one of said replicas;
wherein said codings means comprises a plurality of logic gates receiving at their two inputs terminals respective data of sampled replicas with successive values of said dedicated time delays, and wherein said logic gates are adapted to generate an active output signal if different logic values are applied at their input terminals; and
wherein said selecting means comprise a plurality of switching means each receiving a respective one of said delayed replicas and being controlled by an output signal of a respective one of said logic gates.