Time Domain Measurement: TDR or VNA?

Nowadays, semiconductor technology requires that integrated circuits be interconnected at very high-speed data rates. Taking time domain measurements on the digital links can offer challenges for electronic engineers, one of which is to decide which is the better measurement instrument to use in the given signal integrity environment. The time domain reflectometer (TDR) and vector network analyzer (VNA) are the staple instruments to consider, each one having its pros and cons. Here we compare the responses of the two instruments when used for taking time domain measurements of typical signal integrity devices under test (DUTs): a stripline and a through hole on a FR-4 board.


EMC Test Site Qualifications: Site Voltage Standing Wave Ratio versus Time Domain Reflectometry

Everyone in the EMC business is familiar with the traditional Normalized Site Attenuation test (NSA). However, in February of 2007 CISPR 16-1-4 was published complete with the new Site Voltage Standing Wave Ratio (SVSWR) test. At the time, the American National Standards Institute (ANSI) Accredited Standards Committee (ASC) C63® had developed a draft proposal for C63.4 (Draft 1 - May 20, 2005) called the Time Domain Reflectivity (TDR) measurement. The critical question addressed by this article is which method – SVSWR or TDR - more accurately provides an assessment of the test site. Given the investments companies make in test sites for EMC compatibility, this is key assessment question.