A 0.4V, 720nW CMOS OTA with Improved Gain, UGB and Slew Rate

This paper presents a new ultra-low-voltage ultra-low-power operational transconductance amplifier (OTA) using feed-forward technique. The proposed topology is based on a bulk driven input differential pair employs a Miller compensation technique. In addition, through a coupling capacitance, input signal is simultaneously coupled to gate of idle transistors resulted dramatic enhancement in gain and unity gain-bandwidth (UGB) of the OTA and also improving slew rate. The circuit is designed in the 0.18µm CMOS technology. The simulation results show that the amplifier has a 90dB open-loop DC gain and a unity gain-bandwidth of 127 kHz while operating at 0.4V supply voltage. This technique show remarkable enhancement not even in unity gain-bandwidth and DC gain but also in slew rate compared to the bulk driven input differential pair technique. The total power consumption is as low as 720nW, which makes it suitable for low-power bio-medical applications.

Keywords:

Ultra low power , Ultra low voltage , operational transconductance amplifier , feedforward