Radio frequency composite Class-S power amplifier having discrete power control

Patent metadata

Field	Value
Publication number	US-9325284-B2
Application number	US-201314380915-A
Country	US
Kind code	B2
Filing date	Feb 2, 2013
Priority date	Feb 2, 2013
Publication date	Apr 26, 2016
Grant date	Apr 26, 2016

Abstract

A composite amplifier providing digitally selectable amplification includes a plurality of channels and a combiner. Each of the channels includes a digitally controllable selector, a Class-S power amplifier, and bandpass filter. The digitally controllable selector selectively couples a digital bitstream to the amplifier. The amplifier receives the digital bitstream and provides an amplified signal. The bandpass filter generates a filtered signal as a function of the amplified signal. The combiner couples filtered signals provided by the channels to form a composite output signal. A method of providing digitally selectable amplification includes steps of: selectively coupling a digital bitstream to a plurality of channels in the amplifier; amplifying the digital bitstream to provide an amplified signal associated with a corresponding one of the channels; filtering amplified signals associated with the channels to provide corresponding filtered signals; and combining the filtered signals to generate a composite output signal.

First claim

What is claimed is:

1. A composite amplifier that provides digitally selectable amplification, the composite amplifier comprising:
a plurality of channels, each of the plurality of channels comprising:
a digitally controllable selector;
a Class-S power amplifier, the digitally controllable selector being operative to selectively couple a digital bitstream to the Class-S power amplifier, the Class-S power amplifier being operative to amplify the digital bitstream, thereby providing an amplified signal; and
a bandpass filter coupled with the Class-S power amplifier, the bandpass filter being operative to filter the amplified signal, thereby providing a filtered signal; and

a combiner operative to couple filtered signals associated with the plurality of channels and to generate a composite output signal as a function of the filtered signals.

2. The composite amplifier defined by claim 1 , further comprising a driver operatively coupling the digital bitstream to the digitally controllable selector.

3. The composite amplifier defined by claim 1 , further comprising a binary-to-thermometer-code decoder operatively coupled to the digitally controllable selector, the binary-to-thermometer-code decoder providing a thermometer code control signal to the digitally controllable selector in response to a binary control signal.

4. The composite amplifier defined by claim 1 , wherein each of the plurality of channels further comprises an up-matching circuit operative to match an impedance associated with at least one of the plurality of channels to a prescribed impedance value.

5. The composite amplifier defined by claim 4 , wherein the up-matching circuit comprises at least one of discrete sections and tapered transmission lines.

6. The composite amplifier defined by claim 1 , further comprising an up-matching circuit operative to match an impedance associated with the combiner to a prescribed impedance value.

7. The composite amplifier defined by claim 1 , wherein the digitally controllable selector comprises a three-state buffer and a resistor, the resistor being coupled between an output of the three-state buffer and a voltage source.

8. The composite amplifier defined by claim 1 , wherein the bandpass filter comprises a series resonant circuit centered on a carrier frequency associated with the digital bitstream.

9. The composite amplifier defined by claim 1 , wherein the Class-S power amplifier comprises digital telescoping inverter chains.

10. The composite amplifier defined by claim 1 , wherein the Class-S power amplifier is arranged in at least one of a voltage-mode configuration and a current-mode configuration.

11. An integrated circuit, comprising:
at least one composite amplifier adapted to provide digitally selectable amplification, the at least one composite amplifier comprising:
a plurality of channels, each of the plurality of channels comprising:
a digitally controllable selector;
a Class-S power amplifier, the digitally controllable selector being operative to selectively couple a digital bitstream to the Class-S power amplifier, the Class-S power amplifier being operative to amplify the digital bitstream, thereby providing an amplified signal; and
a bandpass filter coupled with the Class-S power amplifier, the bandpass filter being operative to filter the amplified signal, thereby providing a filtered signal; and

a combiner operative to couple filtered signals associated with the plurality of channels and to generate a composite output signal as a function of the filtered signals.

12. A method of providing digitally selectable amplification in an amplifier, the method comprising steps of:
selectively coupling a digital bitstream to a plurality of channels in the amplifier;
amplifying, using a Class-S power amplifier in each of the plurality of channels, the digital bitstream to provide an amplified signal associated with a corresponding one of the plurality of channels;
filtering, using a bandpass filter, amplified signals associated with the plurality of channels to provide corresponding filtered signals; and
combining the filtered signals to generate a composite output signal as a function of the filtered signals.

13. The method according to claim 12 , wherein the step of selectively coupling is performed using a digitally controllable selector, the method further comprising providing a thermometer code control signal to the digitally controllable selector in response to a binary control signal.

14. The method according to claim 12 , further comprising matching an impedance associated with at least one of the plurality of channels to a prescribed impedance value.

15. The method according to claim 14 , wherein the prescribed impedance value is substantially equal to 50 ohms.

16. An amplification system, comprising:
at least one composite amplifier for providing digitally selectable amplification, the at least one composite amplifier comprising:
a plurality of channels, each of the plurality of channels comprising:
a digitally controllable selector;
a Class-S power amplifier, the digitally controllable selector being operative to selectively couple a digital bitstream to the Class-S power amplifier, the Class-S power amplifier being operative to amplify the digital bitstream, thereby providing an amplified signal; and
a bandpass filter coupled with the Class-S power amplifier, the bandpass filter being operative to filter the amplified signal, thereby providing a filtered signal; and

a combiner operative to couple filtered signals associated with the plurality of channels and to generate a composite output signal as a function of the filtered signals.

17. The system defined by claim 16 , further comprising a binary-to-thermometer-code decoder operatively coupled to the digitally controllable selector, the binary-to-thermometer-code decoder providing a thermometer code control signal to the digitally controllable selector in response to a binary control signal.

18. The system defined by claim 16 , wherein each of the plurality of channels further comprises an up-matching circuit operative to match an impedance associated with at least one of the plurality of channels to a prescribed impedance value.

19. The system defined by claim 18 , wherein the up-matching circuit comprises at least one of discrete sections and tapered transmission lines.

20. The system defined by claim 16 , further comprising an up-matching circuit operative to match an impedance associated with the combiner to a prescribed impedance value.

21. The system defined by claim 16 , wherein the digitally controllable selector comprises a three-state buffer and a resistor, the resistor being coupled between an output of the three-state buffer and a voltage source.

22. The system defined by claim 16 , wherein the bandpass filter comprises a series resonant circuit centered on a carrier frequency associated with the digital bitstream.

23. The system defined by claim 16 , wherein the Class-S power amplifier comprises digital telescoping inverter chains.

Assignees

• Lsi Corp
• Avago Technologies General Ip

Inventors

• Wilson Ross S
• Abdelli Said E
• Kiss Peter
• Laturell Donald R
• Macdonald James F

Classifications

• H03F3/211

  using a combination of several amplifiers (H03F3/60 takes precedence) · CPC title

• H03F3/72

  Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal · CPC title

• H03F1/3241

  using predistortion circuits (H03F1/3211, H03F1/3217 take precedence) · CPC title

• H03F3/245

  with semiconductor devices only · CPC title

• H03F2203/7215

  the gated amplifier being switched on or off by a switch at the input of the amplifier · CPC title