ABSTRACT
Digital-to-analog converters (DAC) enable the interfacing of digital systems with the real world. They are used to transform binary code into an analog output signal, either in the form of a voltage or current. Nyquist DACs are based on various architectures and conversion techniques such as voltage scaling, current scaling, charge scaling or redistribution, and hybrid methods. The effect of mismatches, which are generally caused by integrated circuit process gradients, can be alleviated either by adding a calibration stage to the DAC or by laser trimming components to adjust their values after wafer fabrication. In response to a digital input code, voltage-scaling DACs produce an output voltage by exploiting voltage-divider principle. Current-scaling DACs generally consist of a number of current sources that are selectively switched into a summing node in response to a digital input code. A binary-weighted resistor DAC is realized by summing the current contributions associated to the different bits of a digital input code.
