Miscellaneous active electrical nonlinear devices – circuits – and – Specific signal discriminating without subsequent control – By phase
Reexamination Certificate
1999-09-21
2001-12-11
Lam, Tuan T. (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Specific signal discriminating without subsequent control
By phase
C327S007000
Reexamination Certificate
active
06329847
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a radio device comprising a frequency synthesizer that notably includes a phase discriminator for comparing the phase of a first signal with the phase of a second signal, the phase discriminator being formed by a first sequential circuit for producing output signals that represent the phase difference between said first and second signals.
The invention also relates to such a discriminator and a process for comparing the various phase levels of two signals.
BACKGROUND OF THE INVENTION
Such devices are well known and find many applications, notably in the field of portable telephones that use a great many frequency channels determined by the synthesizer. It will be recollected that a synthesizer is formed, in essence, by a voltage-controlled variable oscillator slaved to a reference frequency after a frequency division that ultimately determines the output frequency of the synthesizer.
When the device is in the stand-by mode, it is more or less periodically to be connected to the network and, for reasons of saving energy, it is desirable for the synthesizer to be longest possible in the state of rest, that is, that this implies that the variable oscillator is synchronized with the reference frequency in the fastest possible way. One of the elements that enable to obtain a fast synchronization is the phase discriminator. In patent document EP 0 500 014 the description of such a discriminator can be found.
If this known discriminator offers good indications as regards the phase differences between −&pgr; and +&pgr;, these indications are no longer sufficient for greater phase differences, thus for signals having different frequencies.
SUMMARY OF THE INVENTION
The invention proposes a device in which the discriminator features a good characteristic of the phase level, so as to notably obtain a fast synchronization of the variable oscillator.
Therefore, such a device is characterized in that the discriminator includes a second sequential circuit for producing a constant signal when said first and second signals have different frequencies.
Thus, thanks to the invention, when the frequencies of the signals are different, the DC signal whose value is equal to a maximum permits the rapid correction of the frequency of the voltage-controlled oscillator to obtain the synchronization of the oscillator in the fastest way.
REFERENCES:
patent: 6100721 (2000-08-01), Durec et al.
patent: 6140853 (2000-10-01), Lo
patent: 6157218 (2000-12-01), Chen
patent: 0500014B1 (1992-08-01), None
patent: 0316543B1 (1993-10-01), None
patent: 2343368 (1977-02-01), None
patent: 1534233 (1978-11-01), None
patent: 2161660A (1986-01-01), None
Dicran Halajian
Lam Tuan T.
Nguyen Hiep
U.S. Phillips Corporation
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