Design of a programmable OTA with multi-decade transconductance adjustment

A programmable operational transconductance amplifier (OTA) structure is presented which permits a g/sub m/ adjustment by greater than two decades without severe degradation in linearity. This is achieved by including a programmable current mirror structure in the OTA output stage for coarse g/sub m/ adjustment in addition to a fine g/sub m/ adjustment via control of a bias current in the OTA differential input stage. Experimental results indicate that less than 1% nonlinearity in the transconductance characteristic is achieved throughout the g/sub m/ adjustment range for input signals less than 1$iV/sub pp/.<
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