Frequency Divider

frequency divider [′frē·kwən·sē di‚vīd·ər]

(electronics)

A harmonic conversion transducer in which the frequency of the output signal is an integral submultiple of the input frequency. Also known as counting-down circuit.

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Frequency Divider 

an electronic device that reduces by an integral factor the frequency of periodic oscillations supplied to it. Frequency dividers are used in frequency synthesizers, in quartz-crystal and atomic clocks, in television apparatus (to synchronize scanning generators), and as timing devices in radar. Electronic counters, self-excited sine-wave generators, regenerative devices, self-excited oscillators with phase-locked frequency control, and relaxation generators are used to divide frequencies.

In a self-excited sine-wave generator, frequency division is achieved by synchronizing the generator’s frequency with a subharmonic oscillation of the frequency of the external periodic signal by means of the locking effect. In a regenerative frequency divider for sine waves, the periodic signal of frequency f, which is to be divided, and a signal of frequency (k - 1)·flk (where k is the scaling ratio), which is produced in the feedback circuit only when a voltage of the frequency being converted is fed to the input of the frequency divider, are fed to the frequency converter. The difference-frequency signal, equal tof/k, is obtained at the converter’s output. In apparatus consisting of a self-excited oscillator with phase-locked frequency control, a phase detector compares the frequency of a harmonic oscillation k times greater than the fundamental frequency of the oscillator with the divided frequency. An error voltage from the output of the phase detector, which is proportional to the difference between the frequencies being compared, is fed to the oscillator and varies its frequency until the divided frequency becomes exactly k times smaller. To divide the repetition rate of the pulse signals, relaxation generators are used as frequency dividers. These generators (multivibrators and blocking oscillators) operate in the periodic mode, with the pulse-repetition rate locked onto a subharmonic frequency, or in the driven mode, with a pulse-repetition period k times higher. In practice k does not exceed 10.

REFERENCES

Frolkin, V. T. Impul’snye ustroistva, 2nd ed. Moscow, 1966.
Gonorovskii, I. S. Radiotekhnicheskie tsepi i signaly, part 2. Moscow, 1967.

IU. B. LIUBCHENKO