Miscellaneous active electrical nonlinear devices – circuits – and – Specific identifiable device – circuit – or system – With specific source of supply or bias voltage
Reexamination Certificate
1998-02-26
2001-04-03
Callahan, Timothy P. (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Specific identifiable device, circuit, or system
With specific source of supply or bias voltage
C327S540000, C323S282000
Reexamination Certificate
active
06211727
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to a voltage regulator and more specifically to a circuit and method for intelligently regulating a supply voltage to a served device in which the supply voltage is regulated according to one or more performance parameters of the served device.
BACKGROUND OF THE INVENTION
The performance characteristics of a Complimentary Metallic Oxide Semiconductor (“CMOS”) device are maximized when the device operates at a certain supply voltage (the “optimal supply voltage” V
OPT
). Although the value of the optimal supply voltage for a CMOS device is specified when the device is designed (the “design voltage”), variations and imperfections in the manufacturing process cause the optimal supply voltage to vary from device to device. Moreover, when the CMOS device is placed in operation, the voltage supplied to the device is rarely equal to the optimal supply voltage, or even the design voltage. In fact, the supply voltage will likely vary over time as operating conditions change.
As a result of these variations, CMOS devices are designed to operate within a specified voltage range, such as plus or minus five to ten percent, around the design voltage. The bottom end of the specified voltage range is limited by the threshold voltage of the CMOS device, which is the minimum voltage required to operate the device. When the voltage supplied to the CMOS device is at or near the threshold level, the device will operate, but at a much slower speed. Conversely, the top end of the specified voltage range is limited by the reliability constraints of the CMOS device. When the voltage supplied to the CMOS device is at or near its maximum operating level, the device will operate at maximum speed, but its power dissipation will be excessive. Accordingly, the goal of any voltage regulation circuit should be to maintain the supply voltage to the CMOS device at or near the optimal supply voltage for the device. Most voltage regulators, however, maintain the supply voltage at or near the design voltage; not the optimal supply voltage.
As discussed above, the manufacture of integrated circuit devices is not 100% repetitive. That is, the geometry of each device varies due to imperfections and variations in the manufacturing process, which in turn affects the performance characteristics of the device. Although, these devices are designed to operate within a specified voltage range, these imperfections and variations may cause some of the devices to operate too slowly, dissipate too much power, or not operate at all, at the minimum or maximum specified voltage, thus making those devices unusable and thereby decreasing the production yield. Furthermore, the production yield for a given device decreases as its complexity increases.
One approach taken by some designers and manufacturers to increase production yield is to provide jumpers or programmable connections on the device to alter its performance so that it operates within the specified voltage range. This method, however, only provides a “coarse” adjustment and does not assure that the device will operate at its optimal level for a given voltage, and will not track the performance of the device, especially over temperature variations.
These problems are multiplied as circuit designers and manufacturers continue to decrease the overall geometry of CMOS devices because the design voltages and associated operating ranges are also decreased. For example, to achieve a certain gate length, such as 0.25 microns, the supply voltage cannot exceed 3.3 volts. If the gate length is decreased to 0.18 microns, the supply voltage cannot exceed 2.0 volts. This smaller voltage range will necessarily further decrease the production yield. Moreover, systems designers employing CMOS technologies often limit the devices they use based on a range of supply voltages. As the dimensions and supply voltages of these devices decrease, the devices themselves may become unattractive to designers who are limited in device selection based on system requirements.
Accordingly, it is desirable to have a circuit and method for intelligently regulating a supply voltage to a served device in which the supply voltage is regulated according to one or more performance parameters of the served device.
SUMMARY OF THE INVENTION
The present invention provides a circuit and method for intelligently regulating a supply voltage to a served device according to one or more performance parameters of the served device. More specifically, the present invention comprises a sensing circuit coupled to the served device for measuring at least one performance parameter of the served device and producing a performance signal which is representative of the measured parameter(s), a discriminator circuit for comparing the performance signal to a reference signal and producing a control signal, and a voltage regulating circuit for adjusting the supply voltage to the served device in response to the control signal.
The present invention also provides a circuit for intelligently controlling a voltage regulating circuit, which provides a supply voltage to a served device. In this embodiment, the present invention comprises a sensing circuit coupled to the served device for measuring at least one performance parameter of the served device and producing a performance signal which is representative of the measured parameter(s), and a discriminator circuit for comparing the performance signal to a reference signal and producing a control signal for controlling the voltage regulating circuit.
The present invention also provides a method for regulating a supply voltage to a served device. The method comprising the steps of measuring at least one performance parameter of the served device and producing a performance signal which is representative of the measured parameter(s), comparing the performance signal to a reference signal and producing a control signal, and regulating the supply voltage to the served device in response to the control signal.
One advantage of the present invention is that the served device operates at or near its optimal supply voltage. As a result, the served device operates at its required speed without unnecessary power dissipation. Another advantage of the present invention is that the production yield for the served device is increased because the question of whether the served device is usable is determined by the performance of the served device and the ability of the present invention to regulate the supply voltage, rather than the performance of the served device over a specified voltage range.
Other objects, features and advantages of the present invention shall be apparent to those of ordinary skill in the art upon reference to the following detailed description taken in conjunction with the accompanying drawings. For example, although CMOS devices are described, the present invention can be applied to other types of semiconductor devices, as well as other electrical devices.
REFERENCES:
patent: 5136260 (1992-08-01), Yousefi-Elezei
patent: 5399958 (1995-03-01), Iyoda
patent: 5528125 (1996-06-01), Marshall et al.
patent: 5546043 (1996-08-01), Pollmeier
patent: 5648766 (1997-07-01), Stengel et al.
patent: 5671149 (1997-09-01), Brown
patent: 5712589 (1998-01-01), Afek et al..
patent: 5883544 (1999-03-01), So et al.
patent: 5945820 (1999-08-01), Namgoong et al.
Callahan Timothy P.
Carlson David V.
Englund Terry L.
Galanthay Theodore E.
Jorgenson Lisa K.
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