0.6-V 1.65-uW second-order Gm-C bandpass filter for multi-frequency bioimpedance analysis based on a bootstrapped bulk-driven voltage buffer
Date
Authors
Director
Publisher
Impacto
Abstract
A bootstrapping technique used to increase the intrinsic voltage gain of a bulk-driven MOS transistor is described in this paper. The proposed circuit incorporates a capacitor and a cutoff transistor to be connected to the gate terminal of a bulk-driven MOS device, thus achieving a quasi- floating-gate structure. As a result, the contribution of the gate transconductance is cancelled out and the voltage gain of the device is correspondingly increased. The technique allows for implementing a voltage follower with a voltage gain much closer to unity as compared to the conventional bulk-driven case. This voltage buffer, along with a pseudo-resistor, is used to design a linearized transconduc- tor. The proposed transconductance cell includes an economic continuous tuning mechanism that permits programming the effective transconductance in a range sufficiently wide to counteract the typical variations that process parameters suffer during fabrication. The transconductor has been used to implement a second-order Gm-C bandpass filter with a relatively high selectivity factor, suited for multi-frequency bioimpedance analysis in a very low-voltage environment. All the circuits have been designed in 180 nm CMOS technology to operate with a 0.6-V single-supply voltage. Simulated results show that the proposed technique allows for increasing the linearity and reduc- ing the input-referred noise of the bootstrapped bulk-driven MOS transistor, which results in an improvement of the overall performance of the transconductor. The center frequency of the bandpass filter designed can be programmed in the frequency range from 6.5 kHz to 37.5 kHz with a power consumption ranging between 1.34 μW and 2.19 μW. The circuit presents an in-band integrated noise of 190.5 μVrms and is able to process signals of 110 mVpp with a THD below −40 dB, thus leading to a dynamic range of 47.4 dB
Description
Keywords
Department
Faculty/School
Degree
Doctorate program
item.page.cita
item.page.rights
© 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license.
Los documentos de Academica-e están protegidos por derechos de autor con todos los derechos reservados, a no ser que se indique lo contrario.