A multistage single sideband generator with improved image rejection

Abstract

A multistage single-sideband generator consisting of a cascade of binary periodically switched phase shifters, e.g. with values of 180 degrees , 90 degrees , and 45 degrees for a double stage unit is described. With a special order of phase shift values, any degree of suppression of the image sideband may be obtained even with imperfect phase shifters merely by increasing the number of stages. This means that any degree of accuracy in the homodyne measurement of amplitude and phase values of a device under test can be obtained using the concept described. The phase and amplitude information is retrieved from a bandpass-filtered low-frequency signal at the mixer output. The receiver seems to be particularly suited for industrial applications of microwaves, where accurate amplitude and phase information is needed and where simplicity and robustness are of prime importance. >