Selecting op amps for high-speed ATE digitizers
Current-feedback amplifiers can provide constant analog bandwidth as they operate in the different gain configurations found in automated test equipment.
By Maurizio Gavardoni, Maxim Integrated Products -- EDN, July 31, 2008
Digitizers play a fundamental role in testing state-of-the-art devices for applications such as DVD, DSL, cellular phones, HDTV, and set-top boxes. The digitizer is an option for ATE systems that capture analog signals in bandwidths from DC to several hundred megahertz, and convert them to digital format for signal processing with digital signal processors (DSPs).
High-performance digitizers employ analog-to-digital converters (ADCs) of 12- to 16-bit resolution, with sampling frequencies of 100 Msps or so. The high resolution allows accurate testing of linearity for most of the digital-to-analog converters (DACs) used in HDTV, set-top boxes, and similar-performance products. One requirement for digitizers is a high bandwidth that approaches the ADC sample rate and even beyond, if the ADC is to implement under-sampling techniques.
At the other extreme, it is also important to extend the analog bandwidth down to a very low frequency or DC. To increase the cost benefit of investing in a high-bandwidth digitizer, the test engineer will want to use it for testing lower-bandwidth devices as well.
This article originally appeared in EDN sister publication Test & Measurement World. Please click here to continue reading "Selecting op amps for high-speed ATE digitizers" on the Test & Measurement World site.
