Active-Gm-RC bandpass filter with 60MHz center frequency and a combined analog-digital tuning system

An active-G_m-RC bandpass filter (BPF) with a combined analog-digital tuning system is presented. The active-G_m-RC BPF biquad features a positive feedback capacitor to enhance the quality factor, and its required number of OTA per filter-order becomes 0.5. A design example for the application to an on-chip equivalent SAW filter with 60MHz center frequency and 8MHz bandwidth is presented. The proposed tuning system can be enabled with a configurable active-G_m-RC BPF/LPF. Behavioral simulations present the proper tuning for the process variation of ±20% in resistors and capacitances, the power can be reduced by a factor of 18.8 over the active-RC BPF.