Very high linearity tunable OTA in 5 V CMOS

摘要

A fully differential OTA with a digitally programmable transconductance value is presented. The design has been optimised for high linearity at moderate frequencies. The simulated THD for a single-ended output of amplitude 2.2 V/sub P-P/ across an 80 kHz bandwidth is >or=-88 dB. When a five-bit tuning code is used the transconductance value is tunable over a range of +or-50% and has a maximum quantisation error of +or-5%. A new automatic tuning scheme requiring no external components is suggested.