Switching and Multiplexing


Defining a test strategy is critical to reducing cost and maximizing the efficiency of your product development and manufacturing organizations. Gain best practices from the Fundamentals of Building a Test System guides to understand the recommended process for building test systems from start to finish. Ensure you have the fundamentals to build a smarter test system that is built to address your needs today and in the future. Switching can be a cost-effective and efficient option for expanding the channel count of your instrumentation, but it is not always the best option. Learn about the four different switching architectures and determine the best strategy to meet the needs of your test system.


Many automated test applications require routing signals to a variety of instruments and devices under test (DUTs). Often the best way to address these applications is to implement a network of switches that facilitate this signal routing between the instrumentation and the DUTs. Switching not only handles this signal routing, but it is also a low-cost way to increase the channel count of expensive instrumentation while increasing the flexibility and repeatability of your measurements.

When adding switching to an automated test system, you have three main options: design and build a custom switching network in-house, use a stand-alone box controlled via GPIB or Ethernet, or use a modular platform with one or more instruments such as a digital multimeter (DMM). Switching is almost exclusively used alongside other instruments, so tight integration with those instruments is often a necessity. An off-the-shelf, modular approach can meet these integration challenges inherent in most common test systems. This guide will outline best practices for integrated switching and multiplexing into your test system.

Topics Covered
  • Switching Architectures for ATE: No switching, switching in the test rack, and switching in the test fixture
  • Common Switching Topologies: Multiplexer (MUX), matrix, sparse matrix, general purpose relays (SPST, SPDT, DPST, and DPDT), and fault insertion units (FIUs)
  • Relay Types: Electromechanical relays (EMR), reed relays, solid-state relays (SSR), and FET relays
  • Key Switching Specifications: Bandwidth, power rating, switching time, isolation, crosstalk, and voltage standing wave ratio (VSWR)
  • Switch Tips and Tricks: Switch expansion, relay maintenance, UL safety certification, triggering, and 2-wire switching



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