Measuring Group Delay of Frequency Converters with Embedded Local Oscillators

Application Notes

Mixers and frequency converters lie at the heart of wireless and satellite communications systems. The requirements on the frequency response and phase linearity of these frequency converters, particularly those used in satellite systems, are increasing. A key measurement that is becoming required is the relative and/or absolute group delay for the frequency converter. However, attributes of these systems require new techniques, and one key attribute is that the Local Oscillator(LO) is not, in any way, accessible. Furthermore, there is not even a common reference frequency signal (typically 10 MHz) that is available to lock the embedded LO with external signal generators.