Patent ID: 7034591
Filing Date: 2006-04-25
Classification: H03L

Abstract:
1. A phase detector for use in a delay locked loop circuit, the phase detector comprising: (a) first circuitry for determining the status of propagation of a first pulse of a reference clock signal through a delay line of the delay locked loop circuit; (b) second circuitry operative in response to the first circuitry for producing a first control signal for causing a loop filter circuit of the delay locked loop circuit to reduce the delay of the delay line, the first control signal representing a first time at which the first pulse of the reference clock signal has progressed entirely through the delay line and a later second time at which a second pulse of the reference clock signal delayed from the first pulse by one reference clock signal period arrives at a first input of the phase detector; (c) third circuitry operative in response to the first circuitry for producing a second control signal for causing the loop filter circuit to increase the delay of the delay line, the second control signal representing a third time at which the second pulse of the reference clock signal arrives at the first input of the phase detector and a later fourth time at which the first pulse of the reference clock signal has progressed to the end of the delay line; and (d) whereby a filter for filtering the first and second control signals and increasing a delay of the delay line in response to the first control signal if the filtering substantially removes the second control signal or decreasing the delay of the delay line in response to the second control signal if the filtering substantially removes the first control signal.