DIGITAL-TO-ANALOG CONVERTER ARCHITECTURE AND METHOD HAVING LOW SWITCH COUNT AND SMALL OUTPUT IMPEDANCE

摘要

A digital-to-analog converter includes a coarse resolution resistor circuit (11) coupled between a first voltage (Vin) and an intermediate voltage (VO) to produce coarse resolution node voltages (V0,...V240), and also includes a fine resolution resistor circuit (20) coupled between the intermediate voltage and a second voltage (GND). One of the coarse resolution node voltages is selected in response to a group of MSB bits of a digital input (D0,l...) to produce a first output voltage (Vout2), and one of the fine resolution node voltages is selected in response to group of LSB bits of the digital input to produce a second output voltage (Voutl), the second output voltage (Voutl) and the first output voltage (Vout2) providing a differential analog output signal (Voutl -Vout2). In one embodiment, the coarse resolution and fine resolution resistor circuits are string resistor circuits, and in another embodiment they are modified R- 2R networks.