Abstract: A simple circuit consisting of a comparator and an exclusive-OR gate is sufficient to double the frequency of a reference signal. Maxim/Dallas > App Notes > AMPLIFIER AND COMPARATOR CIRCUITS Keywords: comparators, exclusive-OR gates, XOR gates, frequency doublers Aug 27, 2004 APPLICATION NOTE 3327 Simple Circuit Doubles Input Frequency A simple circuit consisting of a comparator and an exclusive-OR gate is sufficient to double the frequency of a reference signal. The versatile phase-locked loop (PLL) allows multiplication of a reference frequency with an operating frequency that ranges from "DC to daylight." A PLL is overkill for some applications, however, especially if the input frequency needs only to be doubled. For those cases a simpler approach―such as the circuit in Figure 1 ― will do the job just as well. Figure 1. This circuit doubles the input frequency. The referen……