Two-stage power supply with feedback adjusted power supply rejection ratio

• US 8,125,204 B2
• Filed: 01/10/2008
• Issued: 02/28/2012
• Est. Priority Date: 01/29/2007
• Status: Expired due to Fees

• Current Assignee: Richtek Technology Corporation (MediaTek, Inc.)
• Original Assignee: Richtek Technology Corporation (MediaTek, Inc.)
• Inventors: Liu, Jing-Meng, Pai, Chung-Lung, Chiu, Wei-Che
• Primary Examiner(s): Berhane, Adolf
• Assistant Examiner(s): GBLENDE, JEFFREY A
• Application Number:
  US12/008,272
• Publication Number:
  US 20080180073A1
• Time in Patent Office: 1,510 Days
• Field of Search: 323/273, 323266-268, 323284-285
• US Class Current: 323/274
• CPC Class Codes: G05F 1/575 characterised by the feedback circuit

Abstract

The present invention discloses a power supply comprising: a switching regulator circuit converting an input voltage to an intermediate voltage; a low dropout linear regulator circuit converting the intermediate voltage to an output voltage so as to supply a load current to a load; and a feedback control circuit which increases the noise filtering effect of the low dropout linear regulator circuit when the load current increases.

Claims

1. A power supply, comprising:

a switching regulator circuit converting an input voltage to an intermediate voltage;

a low dropout linear regulator circuit converting the intermediate voltage to an output voltage so as to provide a load current to a load; and

a feedback control circuit which increases the quiescent current of the low dropout linear regulator circuit when the load current increases, wherein the feedback control circuit includes a bit error rate counter electrically connected with the load to generate a bit error rate signal according to an abnormal condition of the load, and the bit error rate signal is converted to a modulation signal to adjust the quiescent current of the low dropout linear regulator circuit.

2. The power supply of claim 1, wherein the low dropout linear regulator circuit includes an error amplifier, and the modulation signal controls the current consumption of the error amplifier.

3. A power supply, comprising:

a switching regulator circuit converting an input voltage to an intermediate voltage;

a low dropout linear regulator circuit including a first error amplifier which controls a power transistor to convert the intermediate voltage to an output voltage so as to provide a load current to a load; and

A power supply, comprising;

a switching regulator circuit converting an voltage to an intermediate voltage;

a low dropout linear regulator circuit including a first error amplifier which controls a power transistor to convert the intermediate voltage to an output voltage so as to provide a load current to a load; and

a feedback control circuit which increases the voltage drop between the intermediate voltage and the output voltage when the load current increases by generating a modulation signal which is inputted to a regulation loop of the switching regulator circuit,

wherein the feedback control circuit includes a bit error rate counter electrically connected with the load to generate a bit error rate signal according to an abnormal condition of the load, and the bit error rate signal is used for generating the modulation signal.