Chapter 7 - Data Converter Support Circuits

Abstract

Voltage references have a major impact on the performance and accuracy of analog systems. Reference circuits and linear regulators actually have much in common. The latter could be functionally described as a reference circuit, but with greater current (or power) output. Accordingly, almost all of the specifications of the two circuit types have great commonality (even though the performance of references is usually tighter with regard to drift, accuracy, etc.). In many cases today the support circuitry is included in the converter package. This is advantageous to the designer since it simplifies the design process and guarantees performance of the system. Noise in voltage references is often overlooked, but it can be very important in system design. Noise is an instantaneous change in the reference voltage. It is generally specified on data sheets, but system designers frequently ignore the specification and assume that voltage references do not contribute to system noise. There are two dynamic issues that must be considered with voltage references: their behavior at start-up, and their behavior with transient loads. Solid-state analog switches and multiplexers have become an essential component in the design of electronic systems which require the ability to control and select a specified transmission path for an analog signal. These devices are used in a wide variety of applications including multi-channel data acquisition systems, process control, instrumentation, video systems, etc. Today, analog switches and multiplexers are available in a wide variety of configurations, options, etc., to suit nearly all applications.