Design and Calibration of a Phase and Amplitude Detector

The phase and amplitude detector (PAD) is one of the key units of the phasing system for BEPCII linac. A new PAD based on I/Q demodulator has been constructed to measure the phase and amplitude of each klystron. To compensate the mismatches of the I/Q demodulator, a calibration algorithm using the adaptive LMS method has been developed to calibrate the I/Q demodulator, and most of the mismatches have been compensated after calibration. Some EMC methods have been adopted to minimize the influence of the noises in the klystron gallery, and the PAD has been running stably and successfully.