Radio frequency signal processing with a monolithic four-quadrant multiplier

A new monolithic and linear four-quadrant multiplier allows replacement of traditional hybrid-based circuits used in frequency conversion, and in-phase or amplitude modulation schemes. We demonstrate the advantages of this approach by evaluating the performances of a wideband amplitude and phase modulation unit built around the 500 MHz multiplier AD834. Key specifications of the unit we assembled are an 80 dB attenuation range, a 100 ns response time, a 360° range of phase shift, and an accuracy up to 0.02°. The device suits the phase and amplitude modulation needs of a nuclear magnetic resonance spectrometer.