This paper presents a low power highly tunable second-order G(m) - C bandpass filter for auditory signal processing of fully implantable cochlear implants. The resonance frequency of the 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 (OTAs) operate in the subthreshold region to achieve low power consumption. The input transistors are driven from the bulk to reduce the transconductance so that the low frequencies of the 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 0.18-mu m CMOS technology on an active area of 0.085mm(2). The filter consumes 13.2nW from a 1V supply and achieves 51.98 dB dynamic range at the resonance frequency of 950 Hz.