A ultra low power, wide input range MICS band channel selection filter on 65 nm CMOS

This paper proposes a low power MICS band receiver channel selection filter on 65 nm CMOS for implantable biomedical devices. This 5^th-order elliptic OTA-C bandpass filter utilizes sub-threshold inverter based OTAs. In order to broaden input range of the filter, the first OTA stage is linearized by using the active-error feedforward technique. The overall filter only consumes 300 μA DC current under 1 V supply, while having an input range up to 0.6 V_pp. The total harmonic distortion (THD) is -58 dB for 1.3 MHz input signal at 0.5 V_pp swing. As a MICS band channel selection filter, it has 300 kHz bandwidth and exhibits more than 45 dB attenuation to the ajacent channel. By using NFET capacitors as OTAs, load, the chip area of this filter is minimized.