Patent
Phase locked loop with means for preventing locking at undesired frequencies
TLDR
In this article, a phase-locked loop (PLL) circuit is proposed for TV tuners, which has a voltage-controlled type oscillator, program divider, a phase detector and a low-pass filter.Abstract:
Disclosed is a phase locked loop (PLL) circuit adapted for use, for example, in TV tuners. The PLL circuit has a voltage-controlled type oscillator, program divider, a phase detector and a low-pass filter, as is the case of conventional PLL circuits, and in addition, includes means for making the phase of the variable signal input to the phase detector lag behind the phase of the reference signal when a program switch for determining the divisor number of the program divider and a power source switch are operated, or means are provided at the output side of the low-pass filter for preventing the oscillator from oscillating at a frequency higher than one octave above a preselected frequency. These means are each effective to avoid the locking of the PLL circuit at a frequency which is a multiple of the desired frequency, thereby to ensure a safe and stable operation of the circuit in which the PLL circuit is incorporated.read more
Citations
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Synthesized multiple conversion receiver system with provision for avoiding receiver self-quieting spurious response
Alan M. Victor,Darrell E. Davis +1 more
TL;DR: In this article, a multiple conversion superheterodyne receiver system includes a first frequency synthesizer capable of generating any one of a number of predetermined first local oscillator frequencies for mixing with an incoming signal to produce a first intermediate frequency.
References
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Patent
Tunable high frequency input circuit for a television receiver that tunes both VHF and UHF channels and can be readily integrated
Klaus Dr Rer Nat Loehn,Georg Dipl-Ing Luetteke,Gerd Dr-Ing Schiefer,Lammert Bruntink,Groenewegen Paulus Petru Maria,Rer Nat Weinerth Han Viktor,Wilhelmus Antonius Joseph Marie Zwijsen,Karel Petrus Van Rooij +7 more
TL;DR: The IC television tuner has a tunable oscillator and a fixed oscillator, two mixer stages and a filter in between as mentioned in this paper, which operates at two intermediate frequencies the first of which lies in the GHz range.
Patent
Arrangement for interference suppression in phase locked loop synchronized oscillators
Pausini F,Squartini G +1 more
TL;DR: In a phase-locked loop synchronized oscillator as discussed by the authors, the phase detector compares an oscillator frequency and a synchronizing frequency to derive a voltage for controlling the oscillator frequencies, and a blocking circuit is used to prevent the memory from changing the value hold before interference occurred.
Patent
Phase-locked frequency synthesizer with means for restoring stability
TL;DR: In this article, the authors proposed a frequency synthesizer that detects, ahead of the frequency and phase comparator, the absence of an output from the frequency countdown circuitry of the feedback portion of the phase-locked loop.
Patent
Method and apparatus for reducing phaselock loop FM'ing
TL;DR: In this article, the loop filter input signal is changed so that high frequency components therein are increased in intensity and yet the average value of this signal is substantially unchanged, after the loop is locked.
Patent
Phase locked loop synthesizer
TL;DR: In this article, a phase-locked loop synthesizer comprising a means for controlling a tuning means is presented, wherein a phase difference between the outputs of a reference signal oscillator and a programmable counter means is detected by a phase detector to obtain a d.c. voltage corresponding to the phase difference, an output having a prescribed frequency is generated by a voltage controlled oscillator frequency is controlled by said d. c. voltage, a part of said output and the output having another reference frequency from a local oscillator are mixed by a mixer, the mixed output is supplied to