Low cost digital-to-analog converter with high precision feedback resistor and output amplifier

摘要

An integrated circuit digital-to-analog converter includes a nichrome feedback resistor having +/-1% accuracy in its output amplifier, a plurality of bit current determining resistors that have +/-30% manufacturing accuracy, a bias voltage circuit that produces a temperature-compensated bias voltage including an integrated potentiometer that is laser trimmed to compensate for the inaccuracy of the bit current determining resistors. The bit current determining resistors thereby produce constant, precise temperature-independent bit currents. The integrated potentiometer is accurately laser trimmed without changing the series resistance of the potentiometer. This prevents current density changes that change the temperature sensitivity of temperature-compensating elements in the bias voltage circuit.