D=A converter with coarse and fine bit decoders

摘要

The coarse bit decoder (10) works on bits of higher order of a digital (M + N) bit input signal, while the fine bit decoder (70) works on lower order bits of the same signal. A current calibrator (20) classifies the currents into numerous stages and transmits a selected current, on output signal reaction from the coarse bit decoder. The output current from the calibrator is converted into voltage by a current to voltage converter (20) and a voltage amplifier (40) transmits the output voltage as a reference voltage. The latter is processed by a voltage divider (50) into several stages and a selected stage is delivered in response to switch control signal from a fine bit decoder. A current compensator (60) acts on the current through the voltage divider for holding the reference voltage constant.