A tunable, video-frequency, low-power, single-amplifier biquadratic filter

In this paper, a tunable single-amplifier biquadratic lowpass filter is presented. It consists of one balanced low-gain current amplifier and a second-order MOSFET–C feedback network. The filter was integrated in a double-poly 0.6 µm CMOS process and operates from a 3.3 V power supply. The pole frequency is tunable from 15.2 to 17.2 MHz, the pole Q is 3, the spurious-free dynamic range is at least 60 dB, and the filter consumes only 2.4 mW per pole. Furthermore, the active area used per pole is only 0.06 mm 2. The filter is well suited for low-power video-frequency applications, and demonstrates that the MOSFET–C filter technique can be applied successfully to filters other than those based on integratorconnected topologies. 1