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

• 作者: Arash Ahmadpour
• 来源期刊: 电路与系统(英文)
• 学科: 工学
• 关键词: Operational TRANSCONDUCTANCE Amplifier (OTA) Common-Mode Feedback (CMFB) Bulk-Input SWITCHED-CAPACITOR (SC) INTEGRATOR Miller-Feed-Forward (MFF)
• 年，卷（期）: 2011,（3）
• 页码范围: 183-189
• 页数: 7页
• 分类号: TN7

摘要

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 (MFF) 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 70.8o phase margin for a 20 PF capacitive load whereas consumes only 25 μw. Finally, an 8th 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.