Abstract: A system and method are provided for controlling the phase of a voltage controlled oscillator output. The method comprises: accepting a plurality of VCO outputs coarsely differentiated by phase; selecting one of the VCO outputs; finely modifying the phase of the selected VCO output; and, supplying the phase modified VCO output. In one aspect, accepting VCO outputs coarsely differentiated by phase includes: accepting a first VCO output (I0); accepting a second VCO output (I1), differentiated approximately 90 degrees from the first VCO output; accepting a third VCO output (Q0), differentiated approximately 90 degrees from the second VCO output; and, accepting a fourth VCO output (Q1), differentiated approximately 90 degrees from the third VCO output. Finely modifying the phase of the selected VCO output includes modifying the selected VCO output in the range between +45 and −45 degrees. In one aspect, the output is modified in 16 discrete steps.

Abstract: A system and method are provided for reducing the threshold bias offset voltage in a comparator, by canceling and bypassing the bias offset current errors. The comparator system comprises amplification stages with bias cancellation circuitry and a threshold setting circuit. The bias offset current cancellation circuit is used to cancel the base current of differential amplifier input emitter follower. The bias offset current cancellation circuit also cancels the loading effect of amplifier input emitter-follower driving stage. The threshold offset voltage is further reduced by the threshold setting circuit. The threshold-setting circuit includes two integrators and a unit gain operation amplifier. The integrators have the input accept a single-ended input signal, an output connected to the negative input of the comparator, and an output connected to the unit gain operational amplifier, whose output is connected to the negative input of the comparator.