Power amplifier with transistor input mismatching

• US 8,237,501 B2
• Filed: 08/31/2011
• Issued: 08/07/2012
• Est. Priority Date: 09/09/2010
• Status: Active Grant

• Current Assignee: MKS Instruments Incorporated
• Original Assignee: MKS Instruments Incorporated
• Inventors: Owen, Christopher Michael
• Primary Examiner(s): NGUYEN, HIEU P
• Application Number:
  US13/222,202
• Publication Number:
  US 20120062322A1
• Time in Patent Office: 342 Days
• Field of Search: 330/295, 330/124.R, 330/251, 330/207.A, 330/255
• US Class Current: 330/251
• CPC Class Codes: H03F 1/086 with FET's
• CPC Class Codes: H03F 1/565 using inductive elements
• CPC Class Codes: H03F 2200/534 Transformer coupled at the input of an amplifier
• CPC Class Codes: H03F 2200/537 A transformer being used as coupling element between two amplifying stages
• CPC Class Codes: H03F 2203/21103 An impedance adaptation circuit being added at the input of a power amplifier stage
• CPC Class Codes: H03F 3/211 using a combination of several amplifiers H03F3/60 takes precedence
• CPC Class Codes: H03F 3/2171 with field-effect devices H03F3/2173 - H03F3/2178 take precedence
• CPC Class Codes: H03F 3/2178 using more than one switch or switching amplifier in parallel or in series H03F3/2173, H03F3/2175 take precedence
• CPC Class Codes: H03F 3/265 with field-effect transistors only

Abstract

A power amplifier includes an input module. The input module includes a transformer and is configured to receive a radio frequency signal and generate output signals. Impedance transformation modules each of which having an output impedance and configured to receive a respective one of the output signals from the transformer. Switch modules each of which comprising a transistor and connected to an output of one of the impedance transformation modules. The transistor has an input impedance and outputs an amplified signal. Each of the output impedances is mismatched relative to a respective one of the input impedances.

Claims

1. A power amplifier comprising:

a first input module comprising a transformer and configured to receive a first radio frequency signal and generate output signals;

impedance transformation modules each of which having an output impedance and configured to receive a respective one of the output signals from the transformer; and

switch modules each of which comprising a transistor and connected to an output of one of the impedance transformation modules, wherein the transistor has an input impedance and outputs an amplified signal, and

wherein each of the output impedances is mismatched relative to a respective one of the input impedances.

2. The power amplifier of claim 1, wherein the input power amplifier comprises:

an inductance having an input and an output, wherein the input of the inductance is configured to receive the first radio frequency signal; and

a capacitance having a first terminal connected to the output of the inductance and to an input of the transformer.

3. The power amplifier of claim 1, wherein the impedance transformation modules are each configured to dissipate reflected power received from the switch modules.

4. The power amplifier of claim 1, wherein:

each of the impedance transformation modules comprises a capacitance,

the capacitance is in series with a respective output of the transformer and is connected to a control input of a respective one of the transistors.

5. The power amplifier of claim 4, wherein the output impedances are output impedances of the capacitances.

6. The power amplifier of claim 4, wherein each of the impedance transformation modules further comprises an inductance in series with a respective one of the capacitances between the transformer and an input of the respective one of the capacitances.

7. The power amplifier of claim 4, wherein the capacitances of the impedance transformation modules increase input impedances and reactances at control terminals of the transistors.

8. The power amplifier of claim 4, wherein the capacitances of the impedance transformation modules reduce gain at frequencies other than a fundamental operating frequency of the power amplifier.

9. The power amplifier of claim 4, wherein each of the impedance transformation modules further comprises a resistance connected between an input of one of the capacitances of the impedance transformation modules and a voltage reference terminal.

10. The power amplifier of claim 9, wherein the resistances reduce impedances at inputs of the capacitances and dissipate reflected power received by the switch modules.

11. The power amplifier of claim 9, wherein:

each of the impedance transformation modules further comprises an inductance; and

the resistances compensate for impedance mismatching of the transistors and the capacitances to impedance match outputs of the inductances.

12. The power amplifier of claim 4, wherein:

each of the impedance transformation modules further comprises a biasing circuit; and

the biasing circuit is connected to an output of one of the capacitances and is configured to generate a bias voltage.

13. The power amplifier of claim 1, further comprising:

a combiner module configured to combine outputs of the transistors to generate a combined output signal; and

an output module configured to filter the combined output signal to generate a power amplifier output signal.

14. The power amplifier of claim 13 comprising:

a second input module configured to receive a second radio frequency signal and generate a conditioned signal;

a driver module configured to receive the conditioned signal and generate the first radio frequency signal; and

a load configured to receive the power amplifier output signal.

15. A power amplifier comprising:

an input module comprising a transformer and configured to receive a first radio frequency signal, wherein the transformer comprises

a first end configured to output a first output signal based on the first radio frequency signal, and

a second end configured to output a second output signal based on the first radio frequency signal;

a first capacitance in series with the first end and having a first output impedance;

a second capacitance in series with the second end and having a second output impedance;

a first transistor comprising a control terminal connected to the first capacitance, having a first input impedance, and outputting a first amplified signal, wherein the first input impedance does not match the first output impedance; and

a second transistor comprising a control terminal connected to the second capacitance, having a second input impedance, and outputting a second amplified signal, wherein the second input impedance does not match the second output impedance.

16. The power amplifier of claim 15, wherein the input power amplifier comprises:

an inductance having an input and an output, wherein the input of the inductance is configured to receive the first radio frequency signal; and

a capacitance having a first terminal connected to the output of the inductance and to an input of the transformer.

17. The power amplifier of claim 15, further comprising:

a first inductance in series between the first end and the first capacitance;

a first resistance having a first terminal and a second terminal, wherein the first terminal of the first resistance is connected to the first inductance and to an input of the first capacitance, and wherein the second terminal of the first resistance receives a reference voltage;

a second inductance in series between the second end and the second capacitance; and

a second resistance having a first terminal and a second terminal, wherein the first terminal of the second resistance is connected to the second inductance and to an input of the second capacitance, and wherein the second terminal of the second resistance receives the reference voltage.

18. The power amplifier of claim 17, wherein:

the first resistance

reduces an impedance at an input of the first capacitance and dissipates a first reflected power signal received by the first transistor, and

compensates for impedance mismatching of an input of the first transistor and an output of the first capacitance to impedance match an output of the first inductance; and

the second resistance

reduces an impedance at an input of the second capacitance and dissipates a second reflected power signal received by the second transistor, and

compensates for impedance mismatching of an input of the second transistor and an output of the second capacitance to impedance match an output of the second inductance.

19. The power amplifier of claim 15, further comprising:

a first biasing circuit configured to generate a first bias voltage, wherein an output of the first capacitance and the control terminal of the first transistor receive the first bias voltage; and

a second biasing circuit configured to generate a second bias voltage, wherein an output of the second capacitance and the control terminal of the second transistor receive the first bias voltage.

20. The power amplifier of claim 15, wherein the capacitances:

increase input impedances and reactances at the control terminals of the first transistor and the second transistor; and

reduce gain at frequencies other than a fundamental operating frequency of the power amplifier.