Interference suppression for switched mode power supply with error correction

Patent metadata

Field	Value
Publication number	US-9479121-B2
Application number	US-201314413960-A
Country	US
Kind code	B2
Filing date	Jul 10, 2013
Priority date	Jul 10, 2012
Publication date	Oct 25, 2016
Grant date	Oct 25, 2016

Abstract

A switched mode power supply arranged to provide a switched supply at one terminal of an inductor, another terminal of the inductor being connected to a first input of an error amplifier having a reference signal at a second input, the error amplifier generating a corrected switched supply at an output in dependence on the difference between signals at its first and second inputs, there being provided a feedback path between the output of the error amplifier and the first input of the error amplifier, and further comprising circuitry for sensing a switcher interference current in the feedback path of the error amplifier, and for adjusting the corrected switched supply output to reduce the switcher interference current in the output.

First claim

What is claimed is:

1. A switched mode power supply comprising:
a first inductor arranged to receive a switched supply at one terminal;
an error amplifier having a first input connected to an other terminal of the first inductor and a second input connected to a reference signal, the error amplifier being configured to generate a corrected switched supply at an output of the error amplifier in dependence on a difference between signals at the first and second inputs;
an impedance connected between the output of the error amplifier and the other terminal of the first inductor;
a resistor connected between the other terminal of the first inductor and the first input of the error amplifier; and
a second inductor connected between the first input of the error amplifier and the output of the error amplifier.

2. The switched mode power supply of claim 1 , wherein the impedance has a value of 1/g m , where g m is the transconductance of the error amplifier.

3. The switched mode power supply of claim 1 , wherein the impedance comprises a reactive element.

4. The switched mode power supply of claim 1 , wherein the impedance is implemented as a printed circuit board track.

5. An envelope tracking power supply including the switched mode power supply of claim 1 .

6. A radio frequency (RF) amplification stage including the switched mode power supply according to claim 1 for providing a power supply to an RF power amplifier.

Assignees

• Snaptrack Inc
• Qualcomm Inc

Inventors

• Wilson Martin

Classifications

• H03F2200/462

  the current being sensed · CPC title

• H02M1/15

  using active elements · CPC title

• H03F2200/432

  Two or more amplifiers of different type are coupled in parallel at the input or output, e.g. a class D and a linear amplifier, a class B and a class A amplifier · CPC title

• H03F3/217

  Class D power amplifiers; Switching amplifiers · CPC title

• H03F1/0227 Primary

  using supply converters · CPC title