Quartz Crystal Drive Level Dependency under High Transmit Current Bursts
High transmit current bursts shift crystal drive levels, causing motional resistance jumps and frequency pulling that degrade wireless packet transmission.
Quartz Crystal Resonator
Meaning
Piezoelectric components provide high stability frequency control through mechanical vibrations induced by an electric field. The quartz crystal resonator utilizes a thin slice of quartz that vibrates at a specific resonant frequency when an alternating voltage is applied.
Physical Structure
Quartz blanks are cut at specific angles to the crystal axes to determine the temperature stability of the finished part. The quartz crystal resonator is then mounted in a hermetically sealed package to protect the surface from moisture and contaminants. High vacuum environments within the package minimize air damping and increase the quality factor.
Frequency Stability
Temperature variations influence the resonant frequency based on the cut of the quartz. A quartz crystal resonator designed with an at-cut provides a stable frequency over a wide thermal range. This stability is required for radio frequency transmission and global positioning receivers.
Mounting Stress
Mechanical forces from the package or the solder process can shift the frequency of the device. When the quartz crystal resonator is soldered to a circuit board, the differential expansion between the material and the enclosure introduces strain. Proper pad design and stress relief prevent permanent offsets in the frequency output.
Characterization of these shifts allows for more accurate frequency compensation in the final system firmware.