Ultra low-power low-voltage active-RC filter with on-chip automatic tuning

An ultra low-power low-voltage active-RC filter design with on-chip automatic tuning system is presented. It is based on the compensation method for compact low-gain amplifier and can be operated at supply voltages down to 0.5 V. Charge pump phase-locked loop technique has been adopted for automatic tuning system. A fifth-order Chebyshev low-pass filters with cut-off frequency tunable from 2 MHz to 10 MHz was designed using a 0.18-μm CMOS process with standard threshold voltage. The output signal-to-in-band integrated noise ratio (SNR) is around 42 dB and the spurious free dynamic range (SFDR) about -42 dBc is also obtained. The filter consumes only 60.9μW with 10 MHz bandwidth.