Loopback Delay Testing Method for Programmable RF Transceivers

Loopback delay is a critical metric for evaluating the real-time performance of programmable RF transceivers in wireless communication, radar, and measurement systems. Conventional measurement approaches often rely on external signal generators and oscilloscopes, resulting in complex setups and susceptibility to instrument-induced errors. This paper presents a fully FPGA-based loopback delay testing method utilizing internal zero-crossing signal generation and detection. The proposed approach was implemented and validated on the Hongxin chip developed by the Beijing Microelectronics Technology Institute. The method requires no external instruments or additional configuration, offering fast, stable, and accurate measurement results. It is versatile and can be widely applied to FPGA+RF transceiver architectures in various system platforms.