Voltage regulator

• US 7,038,434 B1
• Filed: 07/21/2003
• Issued: 05/02/2006
• Est. Priority Date: 08/08/2002
• Status: Expired due to Fees

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: De Jong, Gerben Willem, Brekelmans, Johannes Hubertus Antonius
• Primary Examiner(s): BERHANE, ADOLF D
• Application Number:
  US10/523,730
• Time in Patent Office: 1,016 Days
• Field of Search: 323/265, 323/282, 323/283, 323/284, 323/351
• US Class Current: 323/282
• CPC Class Codes: G05F 1/575 characterised by the feedback circuit

Abstract

A low dropout voltage regulator comprising a series-regulating element (T1) between an input (I) and an output (O) of the voltage regulator, and a differential input error amplifier (1) having a first output (O1) coupled to a control input of the series-regulating element (T1), characterized in that the error amplifier (1) further comprises a second output (O2) coupled to the output (O) via a high-pass filter (5, C1, R1).

Claims

1. A voltage regulator comprising a series-regulating element (T1) between an input (I) and an output (O) of the voltage regulator, and a differential input error amplifier (1) having a first output (O1) coupled to a control input of the series-regulating element (T1), characterized in that the error amplifier (1) further comprises a second output (O2) coupled to the output (O) via a high-pass filter (5, R1, C1).

2. A voltage regulator as claimed in claim 1, wherein a first low-pass filter (3) is coupled between the input (I) of the voltage regulator and an input terminal of the series regulating element (T1).

3. A voltage regulator as claimed in claim 2, wherein the first low-pass filter (3) comprises a first plurality of resistors (R2a, R2b, R2c) connected in series, the first plurality of resistors (R2a, R2b, R2c) being coupled to a first plurality of respective switches (T2a, T2b, T2c) for modifying a time constant of the first low-pass filter (3).

4. A voltage regulator as claimed in claim 1, wherein a first input (+) of the error amplifier (1) is coupled to the input (I) of the voltage regulator through a second low-pass filter (2).

5. A voltage regulator as claimed in claim 4, wherein the second low-pass filter (2) comprises a series coupling of a voltage source (Vdrop), a resistor (R3) and a capacitor (C3).

6. A voltage regulator as claimed in claim 1, wherein the series-regulating element (T1) comprises a plurality of series-regulating elements (T1a, T1b, T1c) coupled to a respective second plurality of selectable resistors (R11a, R12a, R11b, R12b, R11c, R12c).

7. A voltage regulator as claimed in claim 6, wherein the second plurality of selectable resistors (R11a, R12a, R11b, R12b, R11c, R12c) are field effect transistors coupled in pairs, each pair comprising a series connection of a main current channels of two transistors coupled between the input (I) of the voltage regulator and the first output (O1) of the error amplifier (1).

8. An optical detector/amplifier (200) comprising a voltage regulator as claimed in any of the preceding claims for supplying one ore more photo diodes (201) coupled to a variable gain amplifier (202).

9. An optical detector/amplifier (200) as claimed in claim 8, wherein the variable gain amplifier comprises a plurality of cascaded-connected controllable amplifiers.