CAD for circuits with piezoelectric devices

During the last decade commercial software packages for circuit design matured concurrent with PC operating systems. Although optimized for general-purpose design, when used imaginatively, they are useful for circuits that employ piezoelectric devices. This paper illustrates CAD for such circuits with simple examples as the vehicle. The GENESYS 7 suite from Eagleware Corporation is used but the techniques are applicable to other CAD tools. A 4-section bulk-quartz resonator 9 MHz ladder bandpass filter and a SAW resonator 900 MHz oscillator are used to illustrate a few selected CAD techniques for circuits with piezoelectric devices including: 1. Synthesis; 2. Equation defined parameters; 3. Component influences; 4. Standard values; 5. Component tolerances; 6. Resonator cross coupling; 7. Oscillator design methodology; 8. Oscillator loaded Q; 9. Device current; 10. Optimization; 11. Load pulling