Microwave Journal

Rohde & Schwarz Demonstrates New Method for Group Delay Measurement

June 11, 2009

Rohde & Schwarz is demonstrating a new technique for measuring the group delay of frequency-converting devices at the International Microwave Symposium. The technique does not require access to the local oscillator (LO) of the device under test. This is extremely useful in applications such as satellite communication links and highly-integrated devices in which the LO cannot be accessed. The solution is extremely fast, accurate and easy to use. It is available as an option for all four-port R&S ZVA and R&S ZVT Series of vector network analyzers.


Group delay – the time a signal requires to pass from the input to the output of a device – can cause signal distortion if it is not constant within the used frequency band. This makes the measurement of group delay and deviation from linear phase essential to evaluate the performance of wireless communication systems employing higher-order modulation schemes.

Stability and accuracy of conventional group delay measurement methods that require the LO, or try to recon¬struct the LO with an external source, are susceptible to variations of frequency and phase of the DUT’s LO if it is not accessible.

In contrast, the new Rohde & Schwarz technique allows high-precision group delay measurements on converters and mixers even without access to the local oscillator or the reference signal.

The benefits of the technique are equally important for evaluating devices with multiple mixing stages.