Simple Circuit Doubles Input Frequency

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