OTA extended adjustment range and linearization via programmable current mirrors

A technique is presented for obtaining an extended g_m (transconductance) adjustment range and linearization in a CMOS OTA (operational transconductance amplifier) via electronically programmable current mirrors. The mirrors include two outputs for each differential-current input, and the gain at each output may be varied independently. A current differencing technique then results in an overall g_m for the OTA which is proportional to the mirror gain difference. At the same time, the current differencing works to cancel nonlinearities in the transconductance signal. Experimental measurements of a transistor array implementation verify the extended adjustment/linearization technique