A new low-voltage CMOS digitally programmable operational transconductance amplifier (OTA) circuit is presented. The circuit utilizes simple class AB voltage buffers to provide a non slew rate limited performance with low standby power consumption. The OTA can be digitally programmed to maintain a constant settling time for different load capacitors without increasing the standby power consumption. Experimental results from a 1.2-μm chip and comparisons with the regular folded cascode OTA circuit are given. The proposed circuit power consumption is found to be less than one third of a regular folded cascode OTA when driving a load capacitance of 35 pF. For the same power consumption level of 240μA, the new circuit achieves a slew rate more than 10 V/μs while the traditional folded cascode fails to settle.
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