Measuring Group Delay of Frequency Downconverter Devices Using a Chirped RF Modulated Signal

This paper discusses the implementation possibilities for making Group Delay measurements of RF frequency converting devices using a standard RF semiconductor Automatic Test Equipment (ATE) that cannot be done using the standard S-parameter measurement due to the difference in frequency from the input to the output of the device. We discuss how using a chirp waveform modulating an RF generator can be used to sweep the frequency response of a RF frequency-converting device and how to produce such a modulation waveform in digital signal processing. We will describe how to implement a group delay test based on our previous work in the baseband domain and how to understand the errors pertaining to measuring a Radio Frequency Receiver. The measurement of the Group Delay of an RF front-end filter and post down convert IF filter will be demonstrated. We will also describe how to produce and maintain a stable frequency reference so that any down converted signal would be a true representation of the modulation signal applied to the RF Source and not corrupted by Phase Noise. We will show how to implement a group delay test based on our previous work in the baseband domain and how to understand the errors pertaining to measuring a radio frequency receiver. The measurement of the group delay of an RF mixer and pre and post down convert RF/IF filters will be demonstrated. The central goal of this paper is to demonstrate how a group delay test can be done at RF, with a frequency translating device, in a cheap and effective manner on semiconductor Automatic Test Equipment in a production environment.