基于对数检波器的峰值功率计研制

针对北京正负电子对撞机重大改造工程(BEPCII)直线加速器的实际情况和具体需求，为了提高峰值功率计测量精度、进一步降低反射保护报警响应时间并提供实时波形检测手段，对基于集成电路的射频检波芯片进行了调研，研制了一种基于对数检波器、现场可编程门阵列(FPGA)、高速模数转换器(ADC)的新型峰值功率计。通过对不同工作频率下的多点校准，建立分段传递函数，实现功率计校准工作。对功率计样机进行了系统测试，实现了实验室功率测量误差±0.2 dB，BEPCII在线测试的反射保护响应时间2 μs的成绩，功率计已稳定上线运行一段时间。此外，新型峰值功率计具有宽线性动态范围、反射保护报警、内置双通道检波器、用户和工程师双界面、实时波形显示、波形任一点功率测量等特点。

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.