XOR_GATE_OSCILLATOR

Published:2009/7/9 1:44:00 Author:May | From:SeekIC

An exclusive-OR gate, IC1D, turns a simple CMOS oscillator into an FSK generator. When the data input increases, IC1D inverts, and negative feedback through R2 lowers the circuit's output frequency. A low input results in positive feedback and a higher output frequency. R1 and C set the oscillator's frequency range, and R2 determines the circuit's frequency shift. To ensure frequency stability, make R3 much greater than R1 and use a high-quality feedback capacitor. The three gates constituting the oscillator itself need not be exclusive-OR types; use any CMOS inverter.



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