INTERPOLATING DIGITAL-TO-ANALOG CONVERTER WITH SEPARATE BIAS CURRENT SOURCE FOR EACH DIFFERENTIAL INPUT TRANSISTOR PAIR

The most significant portion of a digital word may be converted into a high and a low analog voltage representative, respectively, of the highest and lowest possible values which a digital word could have with the most significant portion. An analog output may be produced by interpolating between the high and the low analog voltage in accordance with the value of the least significant portion of the digital word. A differential transconductance input stage may have pairs of differential input transistors. For each differential input transistor pair, a separate bias current circuit may provide a bias current to the differential input transistor pair, separate from the bias current provided to the other differential input transistor pairs. All bias current circuits may be identical in a linear interpolator. The transconductance input stage may have a gain of at least 20 dB and may result in an integral non-linearity in the analog output of no more than 0.08 times the weight of the least significant bit of the digital word.