Continuous-time-sigma-delta DAC using chopper stabalisation

A sigma-delta digital-to-analog converter comprising:

• a current digital-to-analog converter (IDAC) stage which is operable to generate a current signal depending on an input digital signal, the IDAC having a pair of branches;
• a biasing current source positioned in each branch of the IDAC, each biasing current source being operable to supply a bias current which biases the converter in a mid-scale condition;
• an output current-to-voltage converter which is operable to convert the generated multi-level current signal to a voltage on a continuous-time basis;
• wherein the biasing current sources are connected to the output current-to-voltage converter by a set of switches which are operable to connect the biasing current sources to the output current-to-voltage converter in a first configuration and a second, reversed, configuration.

A method of operating a sigma-delta digital-to-analog converter comprising:

• applying a digital input signal to a current digital-to-analog converter (IDAC) stage to generate a current;
• converting the current to an analog voltage on a continuous-time basis in a current-to-voltage converter;
• and,
• chopper-stabilizing an amplifier of the current-to-voltage converter.

An analog signal resulting from a method of operating a sigma-delta digital-to-analog converter, the method comprising:

• applying a digital input signal to a current digital-to-analog converter (IDAC) stage to generate a current;
• converting the current to an analog signal on a continuous-time basis in a current-to-voltage converter;
• and,
• chopper-stabilizing an amplifier of the current-to-voltage converter.