Mismatch-Immune Digital-to-Analog Converter

A digital-to-analog converter (DAC) comprising:

• a differential amplifier including a non-inverting input coupled to ground, an inverting input, and an output for providing an analog signal;
• a feedback resistor having a first terminal coupled to the output and a second terminal coupled to the inverting input;
• a bias resistor having a first terminal coupled to a positive supply terminal and a second terminal coupled to the inverting input;
• first and second inputs for receiving first and second signals, respectively, the first and second signals comprising an encoded signal pair including overlapping low value portions that are substantially equal in duration to overlapping high value portions within a frame;
• a resistive network including a plurality of resistors and a respective plurality of switches, each resistor including a first terminal coupled to the inverting input and a second terminal coupled to a corresponding one of the respective plurality of switches, each switch responsive to one of the first and second signals to selectively couple the corresponding resistor to one of the positive supply terminal and a negative supply terminal to alter a voltage applied to the inverting input.

A method of providing an analog output signal, the method comprising:

• receiving first and second signals having overlapping low value portions that are substantially equal in duration to overlapping high value portions within a frame;
• applying the first signal to a control terminal of a first switch and the second signal to a control terminal of a second switch to alter a current provided to a common node;
• and
• providing the current into the common node to an output terminal as the analog output signal.