A programmable bandpass array using floating-gate elements

In order to meet the demands of low-power real-time audio signal processing, we present a programmable array of bandpass filters using floating-gate transistors. This bank of analog bandpass filters can be placed before an analog-to-digital converter to perform a frequency decomposition of an audio signal and also allow for analog preprocessing before being transformed into the digital domain. Individual filter taps can easily be tuned to any given frequency and bandwidth because capacitively coupled current conveyers (C⁴s) are used with floating-gate transistors as biasing elements. Offsets and mismatches within the circuit elements are shown to be inconsequential because they can be accounted for and programmed out.