A 0.5V Bulk-Input Operational Transconductance Amplifier with Improved Common-Mode Feedback

Abstract—This paper presents the design of a two-stage pseudodifferential operational transconductance amplifier (OTA). The circuit was designed in a standard 0.18 µm, 0.5 V VT digital CMOS process. An improved bulk-mode common-mode feedback (CMFB) circuit has been designed which does not load the OTA compared to previous design [2]. A self cascode load structure and partial positive feedback provide higher gain. The bulk terminals of all transistors have been biased to lower their Vt and maximize signal swing. The OTA operates at a supply voltage of 0.5 V and consumes only 28 µW of power. Rail-to-rail input is made possible by using the transistor’s bulk terminal as the input. For a load of 20 pF the OTA has a simulated DC gain of 65 dB, a gain-bandwidth product of 550 kHz, and a phase margin of 500 .

• Type: Conference
• Year: 2007
• Where: ISCAS
• Authors: Michael Trakimas, Sameer R. Sonkusale
• Keywords: Bulk Terminal, ISCAS 2007, Standard 0.18 µm, Vt Digital Cmos