A fully reconfigurable low-power floating-gate transistor-capacitor filter

Abstract

This paper presents a fully reconfigurable lowpower filter that is composed of a cascade of floating-gate transistor-capacitor (FGT-C) biquadratic sections suitable for biomedical applications. The proposed FGT-C filter provides both the lowpass and bandpass outputs to the following stage with all filter parameters reconfigurable, including the gains, natural frequency, quality factor, DC levels for input and outputs. The filter topology exhibits good modularity so that the biquadratic sections can be cascaded and scaled up to implement highorder frequency responses easily with efficient area and power consumption. A prototype chip has been fabricated in a 0.35 m 2P4M CMOS process and each FGT-C biquadratic filter occupies an area of 0.0313 mm 2 . From measurement results, the filter consumes 118.4 nW of power with a dynamic range of 45.5 dB while operating at 1.8 V power supply with a 10 kHz bandwidth.

Minimal two‐transistor multifunction filter design

“…At very high frequencies, micro‐strip and resonator filters are employed . However, filter design using single transistors or even a few transistors has remained idle for a long time and subject to trial and error for specific applications . For example, in the work of Pantoli et al .…”

“…Finally, in the work of Peng et al . , a single biquad filter based on six floating gate transistors and numerous biasing transistors was targeted at biomedical applications operating at very low frequencies. In all but the last example cited, the true multifunction output was not available but buffering was still needed.…”

“…At very high frequencies, micro-strip and resonator filters are employed [11,12]. However, filter design using single transistors or even a few transistors has remained idle for a long time [13] and subject to trial and error for specific applications [14][15][16][17][18][19][20][21][22]. For example, in the work of Pantoli et al [16], Stornelli et al [17], and Leuzzi et al [22], targeted at Bluetooth applications, or [21] targeted at radio and radar applications, band-pass filters based on gyrator operation in the gigahertz range were built around single transistors, but not without the presence of additional compensation networks, complicated design, and the need to buffer output signals.…”

“…In [24], two main transistors produced band-pass and low-pass outputs, but the filter coefficients depended heavily on the parasitic gate to source and gate to drain capacitance, which is not always easy to control. Finally, in the work of Peng et al [18], a single biquad filter based on six floating gate transistors and numerous biasing transistors was targeted at biomedical 1450 B. J. MAUNDY ET AL. applications operating at very low frequencies.…”