Glitches in Digital to Analog Converters
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Authors
Nesboe, Simon
Xiong, Xingguo
Issue Date
2014-03-28
Type
Presentation
Language
en_US
Keywords
Engineering , Faculty research day , Digital to analog converters (DACs)
Alternative Title
Abstract
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.