Rectangular Pulse Frequency Doubler

As shown in the figure, this is a rectangular pulse frequency multiplier circuit. This circuit is a digital frequency multiplier, which consists of a six-phase inverter MC840P, two diodes and a capacitor, and its operating frequency range is 1Hz~100kHz. The input signal of the circuit is a square wave. The output is an approximately symmetrical rectangular wave. The capacitive reactance of capacitor C is required to be 1kΩ at the operating frequency. If the output is required to be a symmetrical square wave, a resistor can be connected in series or in parallel with the capacitor. The output circuit includes inverters G3, G4, G5 and G6, which are cross-coupled through diodes D1 and D2. Due to the phase shifting effect of the phase shifting network G1, G2 and C, the phase difference between the two input signals of the output stage is 90o, so the output signal frequency fout=2fin. The circuit works stably, and the same type of circuit can be used to cascade to realize a multi-frequency circuit, and its upper frequency limit can reach 100kHz.