All-digital calibration of string DAC linearity using area efficient PWL approximation: eliminating hardware search and digital division

A method of calibrating a digital-to-analog converter (DAC), the DAC having a digital input and an analog output, the DAC being configured and arranged to produce a voltage level at its analog output in response to a code value applied to its digital input based on a transfer function of the DAC, the method comprising the steps of:

• determining first and second pluralities of code values, each code value of the second plurality representing a respective DAC input code value, successive code values of the first plurality representing uniformly spaced DAC output voltage levels corresponding to the respective code values of the second plurality,
• wherein corresponding pairs of code values of the first and second pluralities of code values define respective breakpoints of a piecewise linear (PWL) approximation of the DAC transfer function;
• storing the first plurality of code values at respective locations within a memory, the respective memory locations being addressable by the second plurality of code values;
• receiving a first input code value by calibration logic circuitry;
• accessing a pair of code values of the first plurality from successive locations within the memory based on the first input code value by the calibration logic circuitry;
• computing a third code value using the accessed pair of code values by a PWL approximation technique by the calibration logic circuitry;
• and
• applying the computed code value to the digital input of the DAC, thereby allowing the DAC to produce a calibrated output voltage level corresponding to the first input code value.