04272729 is referenced by 54 patents and cites 5 patents.

The automatic pretuning of a voltage controlled oscillator in a phase locked loop frequency synthesizer utilizes a successive approximation technique to rapidly bring the coarse tuning voltage of the oscillator to the desired pretuning value. A digital number stored in a digital register is converted to an analog voltage value and applied to the voltage controlled oscillator as the coarse tuning voltage. The frequency of the output signal from the oscillator is compared with a reference signal, and control logic responsive to the sense of the frequency difference between the reference signal and the oscillator output signal adjusts the value of the number stored in the digital register successively from the most significant bit to the least significant bit. A microprocessor can be used to adjust the value of the number stored in the register, as well as provide additional functions such as reverse successive approximation when the synthesizer is switched from one frequency to another frequency. The microprocessor can also be used to sweep the coarse tuning voltage of the oscillator until the output signal is within the capture range of the phase locked loop, and thereafter perform a successive approximation function to bring the coarse tuning voltage to the center of the capture range.

Title
Automatic pretuning of a voltage controlled oscillator in a frequency synthesizer using successive approximation
Application Number
6/37886
Publication Number
4272729
Application Date
May 10, 1979
Publication Date
June 9, 1981
Inventor
William J Riley Jr
Pittsford
NY, US
Agent
L Lawton Rogers III
Assignee
Harris Corporation
FL, US
IPC
H03L 7/12
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