Glitches in Digital to Analog Converters

Digital-to-analog converters (DACs) are widely used for signal processing and other applications. A popular Digital-to-Analog Converter (DAC) topology is the R-2R ladder. It is a simple topology which consists of only two resistors and a switch per bit, and typically one OPAMP buffer at the output. However, such a topology is vulnerable to glitches (voltage spikes) that may occur when several bits in the digital input change at the same time. Although a DAC is often followed by a Reconstruction Filter (RCF), this filter may need to be of a high order to attenuate the voltage spikes sufficiently. Such a filter increases the size of the die in an integrated circuit (IC), or requires more spaces, components and increases cost for a printed circuit board implementation. In some applications, such as an analog control signal to a valve, the filter may not even be necessary, but it is probably desirable to not have glithces. In this work some alternative topologies that eliminate glitches are considered, primarily DACs based on R-2R ladders that accept Gray code input