Oscillators – Automatic frequency stabilization using a phase or frequency... – Afc with logic elements
Patent
1981-04-06
1984-12-25
Grimm, Siegfried H.
Oscillators
Automatic frequency stabilization using a phase or frequency...
Afc with logic elements
331 4, 331 17, 331 27, 328134, 328155, H03L 712
Patent
active
044906889
ABSTRACT:
A sample and hold phase detector for a phase locked loop includes a digital detector for detecting the frequency and phase difference between the reference signal and the voltage controlled oscillator (VCO) signal. In a first mode of operation, the digital detector generates a first signal relating the difference in frequency and in a second mode of operation generates a second signal relating the difference in phase. A capacitor stores the first or second signal depending on the operational mode of the digital detector. The capacitor is selectively discharged in response to a discharge signal produced by the digital detector when either the VCO frequency is higher than the reference frequency or following each detection of a phase difference. A first amplifier is used to bypass a portion of the loop filter to effect rapid changes in VCO frequency in the first mode while a second amplifier couples the control voltage to the VCO via the loop filter to maintain proper VCO frequency in the second mode.
REFERENCES:
patent: 3795870 (1974-03-01), Sanders
patent: 3826988 (1974-07-01), Wise et al.
Motorola MX300 Series "Handie-Talkie" FM Two-Way Portable Radios Theory/Maintenance Manual.
Borras Jaime A.
Suarez Jose I.
Victor Alan M.
Downey Joseph T.
Grimm Siegfried H.
Motorola Inc.
Roney Edward M.
Southard Donald B.
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