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Quartz crystal sinusoidal oscillator

2016-08-01 19:23  
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Quartz crystal sinusoidal oscillator
The circuit shown as the chart is a sine wave oscillator which is composed of the quartz crystal resonator SJT and one gate of six inverter IC CD4069. And comparing with ordinary RC phase shift oscillator, the crystal oscillator's frequency stability can be up to 0.00001 or higher. This is the high targets which RC phase-shift oscillator can not achieve (RC phase shift oscillator frequency stability can only reach the order of 0.01). CMOS NAND gate and negative feedback bias resistor Rl form the inverting amplifier. Quartz crystal SJT and Cl, C2 constitute a 7c positive feedback subcircuit. When quartz crystal is in the vicinity of its natural resonance frequency, it is self-inductive, the inductors and capacitors Cl, C2 constitute a resonant circuit, the forming selective frequency phase shift feedback network is back to the amplifier input to produce oscillation. Adjusting the capacitor C2 can fine-tune the oscillation frequency. Components Selection: Six inverter manifold A: CD4069. Capacitor Cl: 20pF, C2: 3 ~ 22pF, C3: 1000pF. Resistor Rl: 10MΩ. Crystal SJT: 32.768kHz. Circuit connection method: six integrated circuit CD4069 inverter only uses 1 / 6 door, the remaining doors can be used to connect to its input termination VDD or VSS when no other uses, the output is floating.