A Design of Cmos based 4th Order Low Pass Biquad Filter for Biomedical Applications

In this brief a design of CMOS based 4th order low pass biquad filter for biomedical applications is reported. By cascading the 2^nd order P-FVF and N-FVF biquads the 4^th order filter structure are formed. The operating region of the proposed filter is sub-threshold. The cutoff frequency of this circuit is 114.4 Hz. The proposed design is demonstrated in 90nm CMOS technology in the Cadence environment. Low pass filter consumes 2nW with the input voltage of 0.2V. The input-referred noise (IRN) density of the proposed design is 2.8uV/sqrt (Hz). This proposed design gives high passband gain. Because of the low power at low voltage, it will be suitable for biomedical applications.