Digital-to-analog converter with reduced number of resistors

摘要

There is disclosed a digital-to-analog converter (10) including a resistor string (12) having intermediate taps (T1 to Tn+1) at resistor junctions as well as resistor-potential junctions. Switching transistors (M1 to Mn+1) are coupled between a respective intermediate tap (T1 to Tn+1) and an output node (14). Decode circuits (2) are capable of switching at least two transistors to be in the on state at the same time to electrically couple more than one intermediate tap (T1 to Tn+1) to the output node (14) to produce at least one analog output. In one embodiment, one row select line can be energized simultaneously with at least two column select lines. Alternatively, at least two row select lines can be energized simultaneously with one column select line. A DAC (10) in accordance with the present invention is suitable for fabrication in the form of a monolithic integrated circuit and requires less area while maintaining the same degree of resolution as prior art DACs. The DAC also may be used with successive approximation circuitry to provide an analog-to-digital converter. <IMAGE>