Patent ID: 6181181
Filing Date: 2001-01-30
Classification: H03C,H03H

Abstract:
An image suppression mixer, comprising:a first phase shifter for receiving a first input signal and generating first and second signals having a phase difference of a predetermined degree;a second phase shifter for receiving a second input signal and generating third and fourth signals having a phase difference between of a predetermined degree;a third phase shifter, connected to the first phase shifter, for receiving the second signal from the first shifter and shifting the phase of the second signal in accordance with a first control signal;a fourth phase shifter, connected to the second phase shifter, for receiving the fourth signal from the second phase shifter and shifting the phase of the fourth signal in accordance with a second control signal;a first phase difference detection circuit, connected to the first and third phase shifters, for detecting the phase difference between the first and second signals and generating a first detection signal indicating the phase difference;a second phase difference detection circuit, connected to the second and third phase shifters, for detecting the phase difference between the third and fourth signals and generating a second detection signal indicating the phase difference;a differential circuit, connected to the third and fourth phase shifters and the first and second phase difference detection circuits, for receiving the first and second detection signals and generating the first and second control signals, wherein the first control signal originates from the difference between the first and second detection signals, and the second control signal is an inverse of the first control signal; andan image suppression circuit, connected to the first to fourth phase shifters, for receiving the first to fourth signals, generating a first mixing signal by mixing the first and third signals, generating a second mixing signal by mixing the second and fourth signals, and generating a modulation output signal by combining the first and second mixing signals.