Timing-controlled fully programmable analogue signal processors using switched continuous-time filters

Analog signal processors based on continuous-time emulation of sampled-data networks are presented. In these processors, continuous-time signal delay is realized using the phase shift of fixed-frequency, fixed-Q, continuous-time low-pass filters (LPFs), and analog multiplication is accomplished through signal switching using digitally programmable duty cycles. Each coefficient of the processor transfer function is dependently programmable, without requiring selectable capacitor (or resistor) arrays. Experiments verify that this method can be used to construct analog processors with arbitrarily programmable frequency responses. The results presented here are complementary to other results presented earlier by the authors, using sample-data delays