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Oscillator with Frequency Variable in Selectable Steps

IP.com Disclosure Number: IPCOM000103778D
Original Publication Date: 1993-Jan-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 1 page(s) / 63K

Publishing Venue

IBM

Related People

Kostenko, WP: AUTHOR

Abstract

A circuit called a phase-locked loop conventionally has a voltage controlled oscillator, a reference frequency source, a comparator circuit, a filter circuit, and a frequency divider. The frequency divider receives the oscillator output and produces a submultiple in the range of the reference frequency. The comparator compares the phase or frequency of the oscillator and the reference and produces an error signal. The filter transmits the error signal to the oscillator to cause the oscillator to run at a multiple of the reference frequency that is established by the divider circuit.

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Oscillator with Frequency Variable in Selectable Steps

      A circuit called a phase-locked loop conventionally has a
voltage controlled oscillator, a reference frequency source, a
comparator circuit, a filter circuit, and a frequency divider.  The
frequency divider receives the oscillator output and produces a
submultiple in the range of the reference frequency.  The comparator
compares the phase or frequency of the oscillator and the reference
and produces an error signal.  The filter transmits the error signal
to the oscillator to cause the oscillator to run at a multiple of the
reference frequency that is established by the divider circuit.

      The frequency divider is formed by a counter that produces one
output pulse (sent to the comparator) for each repeating cycle of
counting a predetermined number of input pulses (from the voltage
controlled oscillator).  The count is established by a multi-bit
input to the divider circuit.

      Phase-locked loops are often used in the clock circuits that
establish the cycle time of a data processor.  Variable clocks are
useful in testing a data processor in a variable frequency clock for
testing a data processor, the reference frequency is provided by a
reference oscillator and a second frequency divider.  The reference
oscillator runs at a fixed frequency, and the second frequency
divider is adjustable to vary the reference frequency that is
supplied to one input to the comparator circuit.  The frequency...