Abstract
This paper presents a power efficient, bulk driven, source degenerated fully differential operational transconductance amplifier (OTA), operating in the subthreshold region. The input part of the OTA consists of a bulk driven source degenerated differential pair and cross coupled transistors to improve the linearity of OTA. It consists of a bulk driven pair to reduce the supply voltage and to improve the linearity. The proposed fully differential OTA has utilized self-cascode current mirror loads which increases the output impedance and hence the overall intrinsic gain. A subthreshold region is adopted to reduce the power consumption of the circuit. For a 200 mVpp sinusoidal input at 100 Hz, a total harmonic distortion (THD) of −58.56 dB is achieved. The gain, gain bandwidth (GBW), phase margin (PM) and gain margin (GM) values obtained were 48.4 dB, 3.1 KHz, 80° and 19.01 dB, respectively. The common mode rejection ratio (CMRR), power supply rejection ratio (PSRR) and slew rate +/− values were 146.3 dB, 83 dB and 99.56/100 V/ms, respectively. The circuit is capable of operating under a supply voltage of 0.8 V with a power consumption of 59.04 nW, which proves that the circuit is suitable for portable biomedical devices. The proposed circuit is simulated in CADENCE environment virtuoso using LFoundry 150 nm Complementary metal oxide semiconductor (CMOS) process technology.
Highlights
With the increasing demand for portable battery operated biomedical devices, there is a growing need for the development of new design techniques for low voltage (LV), low power (LP), integrated circuits (IC) [1]
AC analysis of the proposed operational transconductance amplifier (OTA) was done with a capacitive load of 1 pF and the DC gain obtained was 48.4 dB with a unity gain bandwidth (GBW) of 3.1 KHz; the phase margin (PM) and
Bulk driven transconductance is lower than that of the gate driven technique, driven but this low transconductance is favorable circuit, because circuit but this technique, low transconductance is favorable for our circuit, because for thisour circuit focuses on lowthis frequency focuses on low frequency biomedical applications
Summary
With the increasing demand for portable battery operated biomedical devices, there is a growing need for the development of new design techniques for low voltage (LV), low power (LP), integrated circuits (IC) [1]. Biomedical devices should be portable and durable due to the constraints of avoiding frequent replacement of batteries and having power efficient circuits as well as low supply voltages so that these devices can be used for a prolonged period of time [3]. There is an increasing density of components on the chip, and a silicon chip can only have a limited amount of power per unit area. Since the increasing density of components allows for more electronic functions per unit area, the power per electronic function has to be lowered in order to Electronics 2018, 7, 41; doi:10.3390/electronics7030041 www.mdpi.com/journal/electronics
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