An ultra low power OTA with improved unity gain bandwidth product

An operational transconductance amplifier (OTA) using dynamic threshold MOS (DTMOS) and hybrid compensation technique is presented in this paper. The proposed topology is based on a bulk and gate driven input differential pair. Two separate capacitors are employed for the OTA compensation where one of them is used in a signal path and the other one in a non-signal path. The circuit is designed in the 0.18μm CMOS TSMC technology. The proposed design technique shows remarkable enhancement in unity gain-bandwidth and also in DC gain compared to the bulk driven input differential pair OTAs. The Hspice simulation results show that the amplifier has a 92dB open-loop DC gain and a unity gain-bandwidth of 135kHz while operating at 0.4V supply voltage. The total power consumption is as low as 386nW which makes it suitable for low-power bio-medical and bio-implantable applications.