Delay locked loop circuit and operating method
AssigneeWinbond Electronics Corp.
InventorChi-Hsiang Sun
Life of this patent
Estimating the term…
Abstract
Provided are a delay locked loop circuit and an operating method, for providing an output clock signal to a bidirectional data strobe (DQS). The delay locked loop circuit includes: a first delay line, configured to delay an input clock signal to generate the output clock signal; a second delay line, configured to receive the output clock signal and delay the output clock signal to generate a feedback clock signal; a phase comparator, configured to compare phases of the input clock signal and the feedback clock signal to adjust a delay of the first delay line; and a control circuit, controlling the second delay line, configured to adjust a delay of the second delay line to be aligned to a delay of an off-chip driver (OCD) coupled to the DQS.
Claims19
A delay locked loop circuit, configured to provide an output clock signal to a bidirectional data strobe, the delay locked loop circuit comprising:
- a first delay line, configured to delay an input clock signal to generate the output clock signal;
- a second delay line, configured to receive the output clock signal and delay the output clock signal by a first delay length to generate a feedback clock signal;
- a phase comparator, configured to compare phases of the input clock signal and the feedback clock signal to generate a first comparison result signal;
- a first control circuit, configured to generate a first delay adjustment signal according to the first comparison result signal to adjust a delay of the first delay line;
- and
- a second control circuit, configured to generate a second delay adjustment signal to the second delay line, such that the first delay length generated by the second delay line is aligned with a second delay length of an off-chip driver coupled to the bidirectional data strobe.
An operating method, applied to a delay locked loop circuit providing an output clock signal to a bidirectional data strobe, the operating method comprising:
- delaying an input clock signal by a first delay line of the delay locked loop circuit to generate the output clock signal;
- receiving the output clock signal by a second delay line of the delay locked loop circuit, and delaying the output clock signal by a first delay length to generate a feedback clock signal;
- comparing according to phases of the input clock signal and the feedback clock signal by a phase comparator of the delay locked loop circuit to generate a first comparison result signal;
- generating a first delay adjustment signal by a first control circuit of the delay locked loop circuit according to the first comparison result signal to adjust a delay of the first delay line;
- and
- generating a second delay adjustment signal to the second delay line by a second control circuit of the delay locked loop circuit, such that the first delay length generated by the second delay line is aligned with a second delay length of an off-chip driver coupled to the bidirectional data strobe.
Dependencies are inferred from the claim text.