Circuit architectures for high linearity monolithic continuous-time filtering

Circuit architectures for high-linearity monolithic continuous-time filters are described based on the use of integrated passive components in active RC structures. Tunability of the frequency response is achieved by arranging either resistive or capacitive elements in programmable arrays. The array value is then set using a digital code produced by an on-chip calibration circuit. The advantages and disadvantages of possible configurations are analyzed, indicating the limits of usefulness. Different filter architectures are considered, and design equations for determining basic cell specifications are given. The analyses are compared with results of experimental integrated filter designs, confirming that both very high linearity (-90 dB) and reasonable tuning accuracy (around ±5%) are achievable