Quadrature detection receiver with separate amplitude and phase control

Claim 1

A receiver for high frequency signals, comprising: a first oscillator providing high frequency oscillator signals in a phase quadrature relationship, and oscillator means providing signals of a frequency f 2 in a phase quadrature relationship, a pair of signal paths connected in parallel to an input, each signal path including a series arrangement including: a first mixing stage receiving a respective one of said high frequency oscillator signals for down-conversion of received high frequency signals, filtering means for selecting a down-converted signal from the respective mixing stage, and a second mixing stage receiving the respective selected high frequency signal and a respective one of said signals of a frequency f 2 for up-conversion of the respective selected down-converted signal, a superposition circuit connected to said second mixing stages for producing, at a signal output, an output signal containing two frequency components having a central frequency value equal to f 2 situated substantially centrally between them, and a control signal arrangement comprising a pair of third mixing stages each having first and second mixing inputs and a mixing output, the two second mixing inputs being connected to said signal output for generating at the respective mixing output respective control signals for separately correcting undesired amplitude and phase differences in signal processing in said signal paths, characterized in that said oscillator means comprises a second oscillator which produces phase quadrature oscillator signals having a frequency 2×f 2 , and a divide-by-two divider between the second oscillator and the second mixing stages, said control signal arrangement includes a pair of further mixing stages having respective third and fourth mixing inputs and further mixing outputs, said third mixing inputs each receiving a respective one of said signals having a frequency 2×f 2 , and said fourth mixing inputs being connected to said signal output, for generating at each of the further mixing outputs a frequency-mirror signal containing two frequency components which are mirror-image components with respect to the two frequency components in said output signal, symmetrical about the frequency f 2 , and said further mixing outputs are coupled respectively to the third mixing inputs of said third mixing stages.