Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – With specific source of supply or bias voltage
Reexamination Certificate
2000-03-29
2001-11-13
Cunningham, Terry D. (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
With specific source of supply or bias voltage
C327S074000, C327S077000, C327S407000, C327S540000
Reexamination Certificate
active
06316991
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to electronic circuits and in particular to circuitry for out-of-calibration circuits and methods and systems using the same.
2. Description of the Related Art
In many voltage controlled circuits, precise voltage calibration of the control signals is critical to optimizing performance. For example, in the case of a phase-locked loop (PLL), the voltage controlled oscillator tuning voltage must be set within calibration limits to insure that the proper PLL output frequency is maintained. The calibrated voltage must then be maintained within those limits throughout circuit operation, notwithstanding the tendency of the signal to drift from the calibrated voltage due to temperature rise and/or fluctuations in the supply voltage.
In order to adjust or compensate for voltage changes in a given signal, some technique is required for monitoring that signal and detecting instances when the signal voltage drifts outside the selected calibration tolerance range. Optimally, this technique should be flexible such that it may be used in various applications calling for different nominal calibration voltages and tolerance ranges. Moreover, such a technique should allow for the calibration tolerances to be easily changed, even on the fly, as allowed by the given operating conditions of the device.
SUMMARY OF THE INVENTION
According to the principles of the present invention, a voltage out-of-calibration detector is disclosed which includes a voltage divider operating between first and second voltage rails and having a plurality of taps for generating first and second comparison voltages. A first set of switches selectively couples at least one of the plurality of taps to the input of a first voltage comparator, the first voltage comparator comparing the first comparison voltage with an input voltage and outputing a signal when the input voltage exceeds the first comparison voltage. A second set of switches selectively couples at least one of the plurality of taps to an input of a second voltage comparator, the second voltage comparator comparing the second comparison voltage with the input voltage and outputing a signal when the input voltage is below the second comparison voltage. Control logic selectively activates the selected ones of the first and second sets of switches in response to received control signals.
The inventive principles allow for the construction and operation of out-of-calibration circuits which can be used in a wide range of applications. By changing the number and size of the resistors within the resistor network, different nominal calibration voltages and tolerance ranges can be obtained. Moreover, the use of switches and control logic allow the calibration tolerances to be easily changed, even on the fly, as required by the given operating conditions of the embodying device.
REFERENCES:
patent: 5388084 (1995-02-01), Itoh et al.
patent: 5426616 (1995-06-01), Kajigaya et al.
patent: 5870401 (1999-02-01), Riley
patent: 6075390 (2000-06-01), Shin et al.
patent: 6211712 (2001-04-01), Baik
Luo Zheng
Muyshondt Gabriel Patrick
Cirrus Logic Inc.
Cunningham Terry D.
Murphy, Esq. James J.
Nguyen Long
Winstead Sechrest & Minick
LandOfFree
Out-of-calibration circuits and methods and systems using... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Out-of-calibration circuits and methods and systems using..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Out-of-calibration circuits and methods and systems using... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2573277