A self-calibration technique for SSB modulators

A new method to adaptively calibrate a Hartley phasing type single-sideband (SSB) modulator for obtaining high carrier and image suppressions is presented. The Hartley SSB modulator is extended by control elements to compensate for circuit non-idealities, a novel monitor circuit to measure the levels of the undesired residual carrier and image tones, and a digital controller. A direct search algorithm adjusts the control elements to maximize modulator performance. The effectiveness of the new technique is demonstrated by an experimental SSB modulator, achieving carrier and image suppressions of 60 dB over a carrier bandwidth of 30 %.