460 μW 32 dB image rejection ratio second-order active-RC complex filter with improved power efficient opamp

An ultra-low-power second-order Chebyshev active-RC complex filter for a low-IF ultra-low-power receiver is presented. By utilising a pole-cancellation push-pull buffer with feedforward phase compensation technology, the operational amplifier (opamp) realises superior stability while maintaining high gain bandwidth and ultra-low power consumption. A second-order complex filter with four proposed opamps and an adaptive bias fabricated in standard 180 nm CMOS process consumes only 460 μW at 1.8 V power supply. The measured centre frequency is 3 MHz and bandwidth is 2 MHz, while it achieves 32 dB image rejection ratio at the centre frequency.