A New Feedforward Technique to Enhance Gain-Bandwidth Product

Abstract — In this paper, a new ultra-low-voltage ultra-low-power operational transconductance amplifier (OTA) using feed-forward technique is proposed. The proposed topology is based on a bulk driven input differential pair employs a gain-stage in the Miller capacitor feedback path to improve the pole-splitting effect. 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. 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 270 kHz while operating at 0.5V supply voltage. This technique show remarkable enhancement in unity gain-bandwidth and also in DC gain compared to the bulk driven input differential pair technique. The total power consumption is as low as 900nW which makes it suitable for low-power bio-medical applications.