Patent ID: 6204709
Filing Date: 2001-03-20
Classification: H03K,H03L

Abstract:
A phase shifter reset circuit, for phase shifting an input signal, having an input and an output, comprising:a phase shifter, having a first input for receiving said input signal, a second input for receiving a phase shift reference signal and an output for outputting a phase shifted input signal, wherein the phase of the input signal is shift by a phase shifter determined by the phase shift reference signal;a resetter, for resetting the phase shift reference signal in response to a trigger signal;a fixed phase shifter, for shifting the phase of said input signal by a predetermined phase shift, connected in parallel with said phase shifter, having an input for receiving said input signal and an output for outputting a fixed phase shifted input signal;a threshold detector circuit, having an input for receiving said phase shift reference signal and an output for outputting a switching signal when said phase shift reference signal reaches a threshold level, substantially equivalent to the phase shift introduced into said input signal by the fixed phase shifter;a bypass circuit, disposed between said phase shifters and said output, having two inputs for receiving, respectively, said phase shifted input signal and said fixed phase shifted signal, a switch for selecting a selected signal from either said phase shifted input signal or said fixed phase shifted signal, an output for outputting said selected signal and means for generating said trigger signal, whereby said switch is responsive to said switching signal to switch from said phase shifted input signal to said fixed phase shifted signal for a predetermined period of time, during which time said trigger signal is generated, before switching back to said phase shifted input signal.