A BICMOS PROGRAMMABLE CONTINUOUS-TIME FILTER USING IMAGE-PARAMETER METHOD SYNTHESIS AND VOLTAGE-COMPANDING TECHNIQUE

This paper presents a BiCMOS realization of a structure-programmable c ontinuous-time filter built with sections synthesized by the image-par ameter method and demonstrating the feasibility of the voltage compand ing technique, The circuit implements any one of four lowpass filters of order 2-5 or one fourth-order bandpass filter by interconnecting a set of identical cells, The filter is obtained by a component level su bstitution transforming a g(m)-C structure into its log-domain equival ent, The g(m)-C' structures are derived from LC ladder prototypes whic h are synthesized using the image-parameter method, This technique can be extended to realize higher order filters using multichip configura tions, As an example, six lowpass filters (order 6-11) and three bandp ass filters (order 6, 8, and 10) have been measured using three chips, The programmable filters can additionally be frequency tuned from 10- 100 kHz with a low total harmonic distortion (THD) despite their class AB operation.