This paper presents a highly tunable low powersecond order Gm−C bandpass filter for auditory signal processing of fully implantable cochlear implants. The resonance frequency of filter is tunable within the daily acoustic band of 200 - 6000 Hz with a tunable quality factor from 1 to 3. The operational transconductance amplifiers operate in sub-threshold region to achieve low power consumption and the input transistors are driven from the bulk to reduce transconductance so that the low frequencies of daily acoustic band are covered. The effect of reduced transconductance on the gain is compensated by increasing the output resistance with folded cascode structure so that unity gain is achieved. The filter was fabricated using TSMC 180 nm CMOS technology on an active area of 0.085 mm2. The filter consumes 13.2 nW from 1 V supply and achieves 51.98 dB dynamic range at the resonance frequency of 950 Hz.