Development of peak power meter based on logarithmic detector

To improve the measurement accuracy of peak power meter of BEPCII linear accelerator, further reduce the response time of reflection protection alarm and provide real-time waveform detection means, the RF detector chip based on integrated circuit has been investigated, and a new type of peak power meter based on logarithmic detector, field programmable gate array (FPGA), and high speed analog-to-digital converter (ADC) has been developed. By the multi-point calibration at different operating frequencies, the segmented transfer function is established, and finally the calibration of power meter is realized. The prototype of power meter has been tested systematically. The results show that the error of power measurement in laboratory is ±0.2 dB and the response time of reflection protection in BEPCII online test is about 2 μs. It has been running steadily online for a period of time. In addition, the new peak power meter has the characteristics of wide linear dynamic range, reflection protection alarm, built-in dual-channel RF detectors, dual interface for users and engineers, real-time waveform display, waveform power measurement at any point, etc.