Linear regulator which provides stabilized current flow

• US 6,369,554 B1
• Filed: 09/01/2000
• Issued: 04/09/2002
• Est. Priority Date: 09/01/2000
• Status: Expired due to Term

• Current Assignee: Marvell Asia Pte Limited (Marvell Technology Group Limited)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Aram, Farbod
• Primary Examiner(s): Vu, Bao Q.
• Application Number:
  US09/654,392
• Time in Patent Office: 585 Days
• Field of Search: 323/271, 323/273, 323/274, 323/282, 323/284
• US Class Current: 323/282
• CPC Class Codes: G05F 1/575 characterised by the feedback circuit

Abstract

A linear regulator operable from a source voltage provides a regulated voltage to a load. The linear regulator includes a bipolar device connected between the source voltage and the load with an output of the bipolar device connected to output the regulated voltage, a feedback amplifier connected in negative feedback relationship between the output of the bipolar device and a reference voltage so as to provide a stabilized voltage, and a capacitor amplification circuit connected between the stabilized voltage and the output of the bipolar device. The capacitive amplification circuit includes a MOSFET n-channel device connected to a base of the bipolar device so as to stabilize current flow from the base to the output of the bipolar device. The capacitor amplification circuit includes an amplifier and a capacitor connected in feedback relationship with the output of the linear regulator, with an output of the amplifier stage providing a reference signal to the gate of the MOSFET device. Most preferably, a 1:n current mirror provides even greater current independence for the frequency characteristics of the linear regulator.

Claims

1. A linear regulator operable from a source voltage to provide a regulated voltage to a load, said linear regulator comprising:

a bipolar device connected between the source voltage and the load, with an output of said bipolar device connected to output the regulated voltage;

a feedback amplifier connected in negative feedback between the output of said bipolar device and a reference voltage so as to provide a stabilized voltage; and

a capacitor amplification circuit connected between the stabilized voltage and the output of said bipolar device;

wherein said capacitor amplification circuit includes a first MOSFET device connected to a base of said bipolar device so as to stabilize current flow from the base to the output of said bipolar device, said first MOSFET device comprising a 1;

n current mirror

wherein said capacitor amplification circuit includes an amplifier and a capacitor in a feedback relationship between an input of said amplifier and the output of the linear regulator, and

wherein said capacitor amplification circuit includes a common-source amplifier communicating between said amplifier and the 1;

n current mirror.

2. A linear regulator according to claim 1, wherein said capacitor amplification circuit includes an amplifier and a capacitor in a feedback relationship between an input of said amplifier and the output of the linear regulator, and wherein said MOSFET device includes a source connected to the base of said bipolar device and a gate connected to an output of said amplifier.

3. A linear regulator according to claim 1, wherein said 1:

n current mirror includes the first MOSFET device and a second MOSFET device, wherein said capacitor amplification circuit includes a current source, wherein said first MOSFET device includes a source connected to the base of said bipolar device and includes a gate, and wherein said current source is connected to a gate and a source of the second MOSFET device and to the gate of the first MOSFET device.

4. A linear regulator according to claim 1, wherein said first MOSFET device is an n-channel device.

9. A linear regulator according to claim 1, wherein said feedback amplifier and said capacitor amplification circuit cause the linear regulator to have a frequency response characteristic that linearly increases as a function of load current up to a predetermine frequency, but then decreases according to a non-linear function of the load current even when the load current continues to increase.

5. A linear regulator operable from a source voltage to provide a regulated voltage to a load, said linear regulator comprising:

bipolar means connected between the source voltage and the load, with an output of said bipolar means connected to output the regulated voltage;

feedback amplifier means connected in negative feedback between the output of said bipolar means and a reference voltage for providing a stabilized voltage; and

capacitor amplification means connected between the stabilized voltage and the output of said bipolar means for stabilizing current flow;

wherein said capacitor amplification means includes a first MOSFET means connected to a base of said bipolar means for stabilizing current flow from the base to the output of said bipolar for stabilizing current flow, said first MOSFET means comprising a 1;

n current mirror means,

wherein said capacitor amplification means includes amplifying means and capacitor means in a feedback relationship between an input of said amplifying means and the output of the linear regulator, and

wherein said capacitor amplification means includes a common-source amplifying means communicating between said amplifying means and the 1;

n current mirror means.

6. A linear regulator according to claim 5, wherein said capacitor amplification means includes amplifier means and capacitor means in feedback relationship between an input of said amplifier means and the output of the linear regulator, and wherein said first MOSFET means includes a source connected to the base of said bipolar means and a gate connected to an output of said amplifier means.

7. A linear regulator according to claim 5, wherein said 1:

n current mirror means includes the first MOSFET means and a second MOSFET means, wherein said capacitor amplification means includes a current source means, wherein said first MOSFET means includes a source connected to the base of said bipolar means and includes a gate, and wherein said current source means is connected to a gate and a source of the second MOSFET means and to the gate of the first MOSFET means.

8. A linear regulator according to claim 7, wherein said MOSFET means is an n-channel device.

10. A linear regulator according to claim 7, wherein said feedback amplifier means and said capacitor amplification means cause the linear regulator to have a frequency response characteristic that linearly increases as a function of load current up to a predetermine frequency, but then decreases according to a non-linear function of the load current even when the load current continues to increase.

11. A linear regulator operable from a source voltage to provide a regulated voltage to a load through a bipolar device that is connected between the source voltage and the load, an output of the bipolar device being connected to output the regulated voltage, said linear regulator comprising:

a feedback amplifier connected in negative feedback between the output of the bipolar device and a reference voltage so as to provide a stabilized voltage; and

a capacitor amplification circuit connected between the stabilized voltage and the output of the bipolar device;

wherein said capacitor amplification circuit includes a first MOSFET device connected to a base of the bipolar device so as to stabilize current flow from the base to the output of the bipolar device, said first MOSFET device comprising a 1;

n current mirror

wherein said capacitor amplification circuit includes an amplifier and a capacitor in a feedback relationship between an input of said amplifier and the output of the linear regulator, and

wherein said capacitor amplification circuit includes a common-source amplifier communicating between said amplifier and the 1;

n current mirror.

12. A linear regulator according to claim 11 , wherein said feedback amplifier and said capacitor amplification circuit cause the linear regulator to have a frequency response characteristic that linearly increases as a function of load current up to a predetermine frequency, but then decreases according to a non-linear function of the load current even when the load current continues to increase.