US5563501A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low voltage dropout circuit with compensating capacitance circuitry
Assignee: Microsemi Corp
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Filing: 1995-06-02
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Granted: 1996-10-08
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Expires: 2015-06-02
Abstract
Abstract An improved low voltage dropout regulation circuit is provided. The internal compensating capacitance coupled to the regulated output port is coupled to a virtual ground and the virtual ground is current buffered for coupling to the control electrode of the path element. For additional frequency compensation, particularly when the path element has a large capacitance, an additional internal compensating capacitance is coupled between the input of the dropout circuit and an output of a transconductance amplifier, which is responsive to the voltage at the regulated output port.
Inventors
- 👤 Shufan Chan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 23:48
CPC Classifications
G; G05; G05F; G05F1/00; G05F1/10; G05F1/46; G05F1/56; G05F1/565
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
223 words
A low voltage dropout circuit comprising: a dropout circuit input and a dropout circuit output and a low voltage port; a path element coupled between the dropout circuit input and the dropout circuit output, the path element having a control port and a parasitic capacitance; a first capacitor having a first and a second port, the first port of the capacitor coupled to the dropout circuit input; an amplifier having a first and a second input and an output, the first input of the amplifier coupled to the reference voltage, the second input of the amplifier coupled to the dropout circuit output, the output of the amplifier coupled to the second port of the first capacitor; a voltage buffer having a first port and a second port, the first port of the voltage buffer coupled to the output of the amplifier and the second port of the voltage buffer coupled to the control port of the path element; a second capacitor having a first and a second port, the first port of the second capacitor coupled to the dropout circuit output; a current buffer having a first port and a second port, the second port of the current buffer coupled to the output of the amplifier and the first port of the current buffer coupled to the second port of the second capacitor.
Claim 2
Dependent Claim
223 words
A low voltage dropout circuit comprising: a dropout circuit input and a dropout circuit output and a low voltage port; a path element coupled between the dropout circuit input and the dropout circuit output, the path element having a control port and a parasitic capacitance; a first capacitor having a first and a second port, the first port of the capacitor coupled to the dropout circuit input; an amplifier having a first and a second input and an output, the first input of the amplifier coupled to the reference voltage, the second input of the amplifier coupled to the dropout circuit output, the output of the amplifier coupled to the second port of the first capacitor; a voltage buffer having a first port and a second port, the first port of the voltage buffer coupled to the output of the amplifier and the second port of the voltage buffer coupled to the control port of the path element; a second capacitor having a first and a second port, the first port of the second capacitor coupled to the dropout circuit output; a current buffer having a first port and a second port, the second port of the current buffer coupled to the output of the amplifier and the first port of the current buffer coupled to the second port of the second capacitor.
Claim 3
Dependent Claim
43 words
A dropout circuit as recited in claim 1, further comprising: a voltage divider coupled between the dropout circuit output and the low voltage port; a node within the voltage divider coupled between the second input of the amplifier and the dropout circuit output.
Claim 4
Dependent Claim
30 words
A dropout circuit as recited in claim 1, wherein the path element has a Miller effect and the current buffer reduces the Miller effect with respect to the second capacitor.
Claim 5
Dependent Claim
26 words
A dropout circuit as recited in claim 1, wherein the current buffer comprises a virtual AC ground coupled to the second terminal of the second capacitor.
Claim 6
Dependent Claim
17 words
A dropout circuit as recited in claim 1, wherein the voltage buffer is a voltage buffer amplifier.
Claim 7
Dependent Claim
15 words
A dropout circuit as recited in claim 1, wherein the amplifier is a transconductance amplifier.
Claim 8
Dependent Claim
31 words
A dropout circuit as recited in claim 1, wherein the path element is a PMOSFET transistor having a gate, and wherein the control port of the path element comprises the gate.
Claim 9
Dependent Claim
15 words
A dropout circuit as recited in claim 1, wherein, the amplifier is a differential amplifier.
Claim 10
Independent Claim
143 words
A method for generating a regulated voltage source at an output port from an unregulated voltage at an input port, the method comprising: controlling the flow of a first current between the input and the output ports with at least one path component having a parasitic capacitance; generating a feedback voltage based upon the voltage at the output port; comparing the feedback voltage with a predetermined voltage; providing a second current based upon the comparison of the feedback voltage with the predetermined voltage; generating a third current by capacitive coupling to the output port and current buffering the capacitive current; summing the second and the third currents at a node; coupling a capacitor between the input port and the node; voltage buffering a sum of currents at the node to provide the control of the flow of the current through the path component.
Claim 11
Independent Claim
143 words
A method for generating a regulated voltage source at an output port from an unregulated voltage at an input port, the method comprising: controlling the flow of a first current between the input and the output ports with at least one path component having a parasitic capacitance; generating a feedback voltage based upon the voltage at the output port; comparing the feedback voltage with a predetermined voltage; providing a second current based upon the comparison of the feedback voltage with the predetermined voltage; generating a third current by capacitive coupling to the output port and current buffering the capacitive current; summing the second and the third currents at a node; coupling a capacitor between the input port and the node; voltage buffering a sum of currents at the node to provide the control of the flow of the current through the path component.
Claim 12
Dependent Claim
49 words
The method of claim 9, wherein the step of generating a feedback voltage based upon the voltage at the output port comprises the steps of coupling a voltage divider between the output port and a low voltage port; coupling the feedback voltage from a node within the voltage divider.
Claim 13
Independent Claim
174 words
A method for making a low voltage dropout integrated circuit, the method comprising: forming in the integrated circuit a path element having a control electrode between an input port and an output port; forming a feedback voltage circuit in the integrated circuit having a node; coupling the node to the output port; forming a reference voltage generator in the integrated circuit; forming an amplifier in the integrated circuit for determining the difference between the voltage at the node and the reference voltage generator; forming a voltage buffer coupled between an output of the amplifier and the control electrode of the path element such that flow of current through the path element results in the voltage at the output port being about a predetermined multiple of the reference voltage; forming a compensating capacitance path between the output port and the output of the amplifier such that a compensating capacitance is isolated to thereby avoid any feed forward circuit path; forming a second compensating capacitance path between the input port and the output of the amplifier.
Claim 14
Independent Claim
174 words
A method for making a low voltage dropout integrated circuit, the method comprising: forming in the integrated circuit a path element having a control electrode between an input port and an output port; forming a feedback voltage circuit in the integrated circuit having a node; coupling the node to the output port; forming a reference voltage generator in the integrated circuit; forming an amplifier in the integrated circuit for determining the difference between the voltage at the node and the reference voltage generator; forming a voltage buffer coupled between an output of the amplifier and the control electrode of the path element such that flow of current through the path element results in the voltage at the output port being about a predetermined multiple of the reference voltage; forming a compensating capacitance path between the output port and the output of the amplifier such that a compensating capacitance is isolated to thereby avoid any feed forward circuit path; forming a second compensating capacitance path between the input port and the output of the amplifier.
Claim 15
Independent Claim
137 words
A method for making an integrated circuit power supply, the method including: forming input and output ports and a path element having a control electrode coupling the input to the output port; forming an amplifier responsive to a voltage difference between a reference voltage and a voltage proportional to the voltage at the output port; forming a voltage buffer between an output of the amplifier and the control electrode of the path element such that the control electrode of the path element is responsive to the output of the amplifier; forming a virtual AC ground in the circuit; and forming a first compensating capacitance coupling the virtual AC ground to the output port, whereby frequency stability of the circuit is improved; forming a second compensating capacitance coupled between the input port and the output of the amplifier.
Claim 16
Independent Claim
137 words
A method for making an integrated circuit power supply, the method including: forming input and output ports and a path element having a control electrode coupling the input to the output port; forming an amplifier responsive to a voltage difference between a reference voltage and a voltage proportional to the voltage at the output port; forming a voltage buffer between an output of the amplifier and the control electrode of the path element such that the control electrode of the path element is responsive to the output of the amplifier; forming a virtual AC ground in the circuit; and forming a first compensating capacitance coupling the virtual AC ground to the output port, whereby frequency stability of the circuit is improved; forming a second compensating capacitance coupled between the input port and the output of the amplifier.
Claim 17
Dependent Claim
30 words
The method of claim 12, wherein the step of forming a virtual AC ground comprises forming a current buffer and coupling the current buffer to the output of the amplifier.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-10-08 | 2000-04-08 | 2000-10-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-10-08 | 2004-04-08 | 2004-10-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-10-08 | 2008-04-08 | 2008-10-08 | $7700.00 | Window Closed / Lapsed |