Miscellaneous active electrical nonlinear devices – circuits – and – External effect – Temperature
Reexamination Certificate
2001-08-14
2002-11-05
Wells, Kenneth B. (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
External effect
Temperature
C327S552000
Reexamination Certificate
active
06476663
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
The invention relates generally to micro-circuitry design. Specifically, this invention relates to a method for reducing supply noise near an on-die thermal sensor.
2. Background Art
In electronic circuits, the system power supply can be shown as an equivalent circuit
10
as shown in FIG.
1
. Specifically, the equivalent circuit
10
includes: a system power supply source
12
; a system resistance (Rs)
14
; a system inductance (Ls)
16
; and a system capacitance (Rc)
18
. Each of these system components
12
,
14
,
16
, and
18
represent an equivalent value of all of the combined respective components in the power supply system. The performance of the circuit
10
is frequency dependent. As shown in the graph of
FIG. 2
, as the frequency of the system increases, the resistance of the circuit increases as well. This increase in resistance continues until a peak
20
is reached at a resonance frequency. Finally, the resistance will subside at even higher frequencies.
The rate of increase in the resistance of the circuit as the frequency approaches its resonance value is quantified as a “Q” value. The “Q” value is calculated as Q=((L/C))/R; where L is the system inductance value; where C is the system capacitance value; and where R is the system resistance value. As shown in
FIG. 2
, under normal operations, the equivalent circuit
10
has a very high Q value
24
near the resonance frequency. A high current transient with the high Q region of the frequency band causes significant noise in the power supply system. Supply noise can result in such problems as component or logic malfunction, signal interference, temperature variation, etc.
It would be advantageous to decrease the Q value of the power supply system and thereby reduce supply noise. A reduced Q value
26
is also shown in FIG.
2
. This Q value
26
would have the advantage of substantially reducing the supply noise of the respective system.
FIG. 3
shows a prior art method of reducing the Q value for a thermal sensor power supply system. A thermal sensor
32
is a component that may be included in an integrated circuit or “chip”. The thermal sensor
32
monitors the temperature of a specific local region of the chip and it may serve as a trouble-shooting device should the temperature get too hot. The thermal sensor
32
is just one of many types of components that are commonly included in an integrated circuit. Each of these components often has a dedicated power supply that is unique and separate from the power supplies of other components. The prior art method used in
FIG. 3
involves inserting a de-coupling capacitor
34
across the power supply in parallel with the thermal sensor
32
. However, the capacitor
34
takes up a significant amount of space on the chip. With chip space at a premium, a space efficient method of reducing power supply noise for a thermal sensor is needed.
SUMMARY OF INVENTION
In some aspects, the invention relates to a method for reducing power supply noise of a thermal sensor, comprising: supplying power to a thermal sensor; and connecting a resistance in parallel with the thermal sensor.
In another aspect, the invention relates to a method for reducing power supply noise of a thermal sensor, comprising: step of supplying power to a thermal sensor; and step of shunting a resistance in parallel with the thermal sensor.
In another aspect, the invention relates to an apparatus for reducing power supply noise of a thermal sensor, comprising: a thermal sensor; a power supply system connected to the thermal sensor; and a shunting resistor connected across the power supply system in parallel with the thermal sensor.
In another aspect, the invention relates to an apparatus for reducing power supply noise of a thermal sensor, comprising: means of supplying power to a thermal sensor; and means of connecting a resistance in parallel with the thermal sensor.
Other aspects and advantages of the invention will be apparent from the following description and the appended claims.
REFERENCES:
patent: 4441023 (1984-04-01), Docter et al.
patent: 5345055 (1994-09-01), Leung
patent: 6040668 (2000-03-01), Huynh et al.
patent: 6121615 (2000-09-01), Ito
patent: 6308519 (2001-10-01), Bielinski
Amick Brian W.
Gauthier Claude R.
Liu Dean
Thorp Tyler J.
Trivedi Pradeep R.
Cox Cassandra
Rosenthal & Osha L.L.P.
Sun Microsystems Inc.
Wells Kenneth B.
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