With the development and requirements of quartz resonator technology, impedance meters have been widely used in the production and inspection of quartz resonators, and according to the operating frequency range of quartz resonators, they have been series, as shown in Table 1.

    Figure 1

    The circuit structure of the impedance meter is in the range of 1 ~ 100MHz, as shown in Figure 1. It is actually a variant of a capacitive three-point (Corpitz) oscillator. A quartz resonator is connected in series in the middle of the inductor L to control the oscillation frequency and amplitude. When the grid LC channel is adjusted to the minimum impedance frequency of the quartz resonator, the indication of the grid current meter A is the largest. At this time, it can be considered that the oscillation frequency is equal to the series resonance frequency fs of the resonator, and is directly measured by an electronic counter at the output end of the impedance meter.

    In order to ensure stable oscillation of the oscillator, the resistance RT cannot be too small. Generally, RT is required to be greater than the dynamic resistance R1, and when RT is greater than R1, it will affect the measurement accuracy. This is the main reason why the measurement accuracy of the impedance meter is lower than the transmission method.