Patent ID: 6225929
Filing Date: 2001-05-01
Classification: H03M

Abstract:
A digital-to-analog converter (DAC) for converting a digital input signal having N bits to a substantially equivalent analog voltage output signal, the DAC comprising:a resistor string having N resistors serially coupled between a ground node and the analog voltage output signal and having N nodes (node 1-node N), wherein nodes 1 through (N-1) are defined at junctions between the N resistors and node N is coupled to the analog voltage output signal; andN switchable current sources, each switchable current source including:a first transistor having a source coupled to a power source, a drain, and a gate coupled to a first bias voltage;a second transistor having a source coupled to the drain of the first transistor, a drain providing a current output coupled to a corresponding one of the N nodes of the resistor string, and a gate; anda third transistor having a source coupled to ground, a drain coupled the drain of the first transistor, and a control gate receiving a corresponding one of the N bits of the digital input signal.