Realization of an analog biquadratic filter using log-domain techniques

We propose the design of a biquadratic filter using log domain filtering techniques. The filter is designed using a purely current-mode approach. This biquadratic filter realizes low pass, high pass, band pass, band elimination and all pass filter functions. The designed filter is electronically tunable over several decades of frequency by changing the magnitude of current source. The complexity is low as current mirrors are used as opposed to operational amplifiers, gyrators or OTAs.