Octave-Band High Precision Balanced Modulator

This paper describes an octave bandwidth component that closely approximates an ideal bi-phase linear modulator at microwave frequencies. PIN diodes in a balanced configuration of hybrid couplers were combined to realize the component in a microstrip circuit. Phase errors of 2 degrees or less were achieved over an octave band for a bi-phase modulator application. The modulator was also used to form a frequency translator with a minimum carrier suppression of 30dB and sideband suppression of 20dB over the 4-10GHz frequency band.