Patent ID: 6194929
Filing Date: 2001-02-27
Classification: H03L

Abstract:
A delay-locked loop comprising:a phase detection circuit coupled to receive a first signal and a second signal, the phase detection circuit generating a phase-error output signal indicative of whether the first signal is ahead of or behind the second signal in phase responsive to receiving the first and second signals;a charge pump circuit coupled to receive a phase-error input signal derived from the phase-error output signal, the charge pump circuit generating a plurality of control output signals, each of the control output signals being based upon the phase-error input signal and being based upon at least one signal derived from one other of the control output signals, the charge pump circuit generating first and second control output signals, the charge pump circuit includinga first charge pump coupled to receive the phase-error input signal and a signal derived from the second control output signal, the first charge pump determining the value of the first control output signal responsive to a value of the phase-error input signal and responsive to whether the signal derived from the second control output signal is within one of a first and second range;a second charge pump coupled to receive the phase-error input signal and a signal derived from the first control output signal, the second charge pump determining the value of the second control output signal responsive to a value of the phase-error signal and responsive to whether the signal derived from the first control output signal is within another of a first and second range; and,a phase shift circuit coupled to receive a plurality of control input signals and a plurality of periodic input signals, the control input signals derived from the control output signals, each of the periodic input signals having a different phase, the phase shift circuit applying the control input signals to select from among the periodic input signals to generate a periodic output signal, the periodic output signal being one of the first and second signals; whereinthe first charge pump causes the value of the first control output signal tochange value in a first direction responsive to the phase-error input signal indicating the first signal is ahead of the second signal in phase and the signal derived from the second control output signal being within the first range;change value in a second direction responsive to the phase-error input signal indicating the first signal is ahead of the second signal in phase and the signal derived from the second control output signal being within the second range;change value in the second direction responsive to the phase-error input signal indicating the first signal is behind the second signal in phase and the signal derived from the second control output signal being within the first range; andchange value in the first direction responsive to the phase-error input signal indicating the first signal is behind the second signal in phase and the signal derived from the second control output signal being within the second range; andthe second charge pump causes the value of the second control output signal tochange value in the first direction responsive to the phase-error input signal indicating the first signal is ahead of the second signal in phase and the signal derived from the first control signal being within the first range;change value in the second direction responsive to the phase-error input signal indicating the first signal is ahead of the second signal in phase and the signal derived from the first control signal being within the second range;change value in the second direction responsive to the phase-error input signal indicating the first signal is behind the second signal in phase and the signal derived from the first control signal being within the first range; andchange value in the first direction responsive to the phase-error input signal indicating the first signal is behind the second signal in phase and the signal derived from the first control signal being within the second range.