Crystal Real-time Measurement System Design

In the paper, the design of the real-time test system for crystal parameters is presented. The signal generator of sweep frequency based on DDS device AD9852, the signal measuring circuit based on gain and phase detector AD8302, and the real-time control and deal circuit based on TMS320VC5416 and the design of high-speed printed digital & analog circuit board are discussed in details. The system can generate sweep frequency signal with frequency range from 100kHz to 150MHz and power range from -40dBm to +18dBm, and measure the gain and phase of the crystal. According to the gain and phase information and the IEC-444 Standard, crystal parameters can be calculated, such as nominal frequency, series resistance, shunt capacitance, motion capacitance, motion inductance, Q factor and so on.