An Ultra Low-Voltage and Low-Power OTA Using Bulk-Input Technique and Its Application in Active-RC Filters

Arash Ahmadpour
<span title="">2011</span> <i title="Scientific Research Publishing, Inc,"> <a target="_blank" rel="noopener" href="https://fatcat.wiki/container/7xp3xydesfgwbon56mgufqzvea" style="color: black;">Circuits and Systems</a> </i> &nbsp;
This paper presents the design of a two-stage bulk-input pseudo-differential operational transconductance amplifier (OTA) and its application in active-RC filters. The OTA was designed in 90 nm CMOS process and operates at a single supply voltage of 0.5 V. Using a two-path bulk-driven OTA by the combination of two different amplifiers the DC gain and speed of the OTA is increased. Rail-to-rail input is made possible using the transistor's bulk terminal as in input. Also a Miller-Feed-forward
more &raquo; ... F) compensation is utilized which is improved the gain bandwidth (GBW) and phase margin of the OTA. In addition, a new merged cross-coupled self-cascode pair is used that can provide higher gain. Also, a novel cost-effective bulk-input common-mode feedback (CMFB) circuit has been designed. Simplicity and ability of using this new merged CMFB circuit is superior compared with state-of-the-art CMFBs. The OTA has a 70.2 dB DC gain, a 2.5 MHz GBW and a 70.8° phase margin for a 20 PF capacitive load whereas consumes only 25 µw. Finally, an 8 th order Butterworth active Biquadrate RC filter has been designed and this OTA was checked by a typical switched-capacitor (SC) integrator with a 1 MHz clock-frequency. Figure 1. One stage of proposed bulk-input differential pair.
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