Electricity: power supply or regulation systems – Output level responsive – Using a three or more terminal semiconductive device as the...
Reexamination Certificate
1999-08-31
2002-06-25
Riley, Shawn (Department: 2838)
Electricity: power supply or regulation systems
Output level responsive
Using a three or more terminal semiconductive device as the...
C323S288000, C363S060000
Reexamination Certificate
active
06411069
ABSTRACT:
COPYRIGHT NOTICE
A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to voltage regulation. The invention is also related to dividing voltage sources. The invention is more particularly related to the division and provision of regulated voltage in microelectronic circuits. The invention is still more particularly related to the provision of capacitor divided voltage provided for power requirements of microelectronic devices, particulary flash memory devices.
2. Discussion of Background
Most electronic systems being designed today use some form of voltage regulation to ensure circuit stability in the face of changes in load current or supply voltage. In addition to being a requisite for proper or stable circuit operation, many times the circuit design can be simplified with resultant cost reductions if it is based on using a regulated supply. Regulated voltage supplies are also useful to provide a voltage level for comparison of other voltages, such as testing charge levels of other devices in an electronic device. The degree of accuracy that the voltage regulator must provide varies considerably with the function performed by the electronics. As a result, there are many different methods for providing the regulation available to the designer.
For many years gas tubes have been used to provide voltage regulation. This is because the characteristic maintaining voltage of these gas discharge tubes remains fairly constant over a relatively wide range of operating currents. Thus, they can absorb any reasonable voltage or current fluctuations occurring in normal operation, keeping the load voltage fairly constant. However, such devices have limited applicability and are not suitable for microelectronic devices.
Solid state voltage regulator diodes or Zeners have been popular since the late 1950's when they replaced bulky vacuum tubes. Zener diodes primarily serve as voltage regulators with variable operating currents when placed in parallel across a load to be regulated.
Generally speaking, voltage regulation within modern microelectronic devices utilize a voltage source which is regulated based on it's output. The process is illustrated in FIG.
1
. At step
100
, an output voltage is sampled. The output voltage is provided from a power supply. At step
110
, the sampled voltage is compared to a know value or reference (band gap reference, for example). The reference can be any stable value which provides an indication as to whether the power supply is providing the required or designed power output. Finally at step
120
, feedback from the step
110
comparison is fed back into the power supply to adjust the power level output (output voltage). In this manner a regulated power supply is provided.
FIG. 2
illustrates a typical arrangement of electronics for implementing the above described process. A voltage source
200
provides a supply voltage V
supply
. The V
supply
is divided by resistor pair
210
,
220
to provide a divided voltage
230
. The divided voltage
230
is typically divided from the V
supply
to provide a proper voltage level for any connected electronics and a design of the remaining circuit. In this case, the divided voltage provides a voltage for a comparison circuit
250
.
The divided voltage
230
is input to the comparison circuit
250
and compared to a reference voltage
240
. The comparison circuit
250
is a standard comparator or amplifier configured to produce some difference or adjustment between the divided voltage
230
and the reference voltage
240
, producing a feedback voltage
260
.
The feedback voltage
260
is then fed back into the voltage supply
200
where it has the effect of either lowering or increasing a voltage level produced, resulting in a regulated power supply. As thus illustrated, the circuit in
FIG. 2
performs the method described above for power regulation and also illustrates a method of producing additional specific voltages (divided voltage
230
, for example) from a single voltage source using a resistor divider (resistor pair
210
,
220
).
Resistor dividers are common methods for providing specific voltages from a single power source. However, such arrangements require that power is constantly drawn from the voltage source to provide the voltage, and are thus inefficient. One method that does not continuously draw power to provide a divided voltage is illustrated in
FIG. 3. A
capacitor pair
310
,
320
is shown that divides a voltage to produce a capacitor divided voltage
330
. The capacitor divided voltage is provided to comparison circuit
250
to produce the feedback voltage
260
.
The capacitor pair
310
,
320
are charged up by a voltage source similar to voltage source
200
.
FIGS. 4A-B
illustrates the charge of the capacitors
310
,
329
charged up from t
1
to t
2
, to provide a voltage level for comparison purposes. Unfortunately, capacitors leak charge (see t
2
to t
3
, for example) or will have charge drawn from them for circuit operation and therefore are unsuitable for stable continuous operations.
SUMMARY OF THE INVENTION
The present inventor has realized that continuous current voltage dividers, such as resistor pairs, are unsuitable for modern electronic devices, particularly for on chip devices or pumps that have limited power resources. The present inventor has realized that capacitor dividers are an ideal way to maintain a voltage level for operating purposes within modern microelectronic devices, and that a method of maintaining a charge level in the capacitors without continuous power application would overcome the problems in the prior art.
Roughly described, the present invention provides a nominal power application at predetermined intervals to refresh and maintain a charge level in a capacitor voltage divider circuit. The refresh is performed by calculating an amount of time that a capacitor in the capacitor divider circuit maintains a sufficient charge, and, before that time period has expired, turning the circuit off and reinitializing the capacitors in the circuit, and turning the circuit back on. The timing is generally based on a period of the pump (or voltage supply) and utilizes detailed set of electronics to implement the selected timing regiment.
The present invention is a device that provides a selected voltage level with a minimum of power drain from a supply voltage. The present invention includes a refresh mechanism for initializing capacitor nodes of a capacitor voltage divider circuit to maintain a predetermined voltage division of a voltage source between a capacitor pair of the capacitor voltage divider.
An embodiment of the present invention includes a timing circuit capable of refreshing a capacitor voltage diver circuit at a frequency tied to a frequency of a pump supplying the voltage divider by the capacitor voltage divider circuit.
The present invention can be constructed from parts already present on a microelectronic circuit to implement the timing and functions of the present invention.
The invention may be embodied in either of: a sampling circuit having, a sampling node, and a refresh circuit configured to refresh the sampling circuit at an interval rate of less than an amount of time that charge leakage of the sampling circuit degrades a voltage measurement made at the sampling node beyond a threshold amount; and a regulated voltage supply, having a voltage source, a sampling circuit connected to an output of said voltage source and configured to sample the output without drawing current from said voltage source, and a feedback circuit configured to provide a signal that adjusts an amount of voltage supplied at the output based on the sampled output.
The invention may al
Advanced Micro Devices , Inc.
Fliesler Dubb Meyer & Lovejoy
Riley Shawn
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