Power amplifier with load switching circuit

• US 6,806,767 B2
• Filed: 07/09/2002
• Issued: 10/19/2004
• Est. Priority Date: 07/09/2002
• Status: Expired due to Term

• Current Assignee: Skyworks Solutions Incorporated
• Original Assignee: Anadigics Incorporated (Coherent Corp.)
• Inventors: Dow, Gee Samuel
• Primary Examiner(s): NGUYEN, LONG T
• Application Number:
  US10/190,567
• Publication Number:
  US 20040008082A1
• Time in Patent Office: 833 Days
• Field of Search: 330/51, 330/129, 330/133, 330/285, 330/302, 330/303, 330/305, 330/306
• US Class Current: 330/51
• CPC Class Codes: H03F 1/14 by use of neutralising means
• CPC Class Codes: H03F 1/30 Modifications of amplifiers to reduce influence of variations of temperature or supply voltage or other physical parameters in differential amplifiers H03F3/45479
• CPC Class Codes: H03F 1/3241 using predistortion circuits H03F1/3211, H03F1/3217 take precedence
• CPC Class Codes: H03F 1/56 Modifications of input or output impedances, not otherwise provided for
• CPC Class Codes: H03F 2200/318 A matching circuit being used as coupling element between two amplifying stages
• CPC Class Codes: H03F 2200/411 the output amplifying stage of an amplifier comprising two power stages
• CPC Class Codes: H03F 2200/75 the amplifier stage being a common source configuration MOSFET
• CPC Class Codes: H03F 3/189 High-frequency amplifiers, e.g. radio frequency amplifiers
• CPC Class Codes: H03F 3/191 Tuned amplifiers H03F3/193, H03F3/195 take precedence
• CPC Class Codes: H03F 3/60 Amplifiers in which coupling networks have distributed constants, e.g. with waveguide resonators H03F3/54 takes precedence

Abstract

A power amplifier circuit includes a power amplifier responsive to a power mode signal, the power amplifier having a power amplifier output node, and a power amplifier load circuit also responsive to the power mode signal, the power amplifier load circuit having a load circuit input node connected to the power amplifier output node. The power amplifier load circuit has a first transmission line coupled between the load circuit input node and a first node, a harmonic filter coupled between the load circuit input node and a common node, a first capacitor coupled between the first node and the common node, and a first switch coupled between the common node and ground, where the first switch is responsive to the power mode signal.

Claims

1. A power amplifier circuit comprising:

a power amplifier responsive to a power mode signal, said power amplifier having a power amplifier output node; and

a power amplifier load circuit also responsive to said power mode signal, said power amplifier load circuit having a load circuit input node connected to said power amplifier output node;

wherein the power amplifier load circuit comprises;

a first transmission line coupled between the load circuit input node and a first node;

a second transmission line coupled between the first node and a second node;

a harmonic filter coupled between the load circuit input node and a common node;

a first capacitor coupled between the first node and the common node; and

a first switch coupled between the common node and ground,

wherein the first switch is responsive to said power mode signal.

2. The power amplifier circuit according to claim 1, wherein the power amplifier load circuit further comprises:

a second capacitor and a second switch connected to one another in series, between the second node and ground,

wherein the second switch is responsive to a band select signal.

3. The power amplifier circuit according to claim 1, wherein the power amplifier load circuit further comprises:

a second capacitor coupled between the second node and the common node.

4. The power amplifier circuit according to claim 1, wherein the power amplifier load circuit further comprises:

a second capacitor coupled between the second node and ground.

5. The power amplifier circuit according to any one of claims 2, 3, and 4, wherein the power amplifier load circuit further comprises a third transmission line connected between the second node and a load circuit output node.

6. The power amplifier circuit according to claim 1, wherein the power amplifier load circuit further comprises:

a fourth transmission line coupled to the amplifier output node;

an inductor coupled between the fourth transmission line and a battery voltage input node; and

a capacitor coupled between the battery voltage input node and ground.

7. The power amplifier circuit according to claim 1, wherein the power amplifier an the power amplifier load circuit are implement as a GaAs integrated circuit.

8. The power amplifier circuit according to claim 1, wherein the power mode signal corresponds to one of a low power mode signal and a high power mode signal, wherein the low power mode signal corresponds to a low-power mode of the power amplifier and the high power mode signal corresponds to a high-power mode of the power amplifier.

9. The power amplifier circuit according to claim 8, wherein the low power mode signal has a voltage of approximately 0V and the high power mode signal has voltage of approximately 3V.

10. The power amplifier circuit according to claim 1, wherein the harmonic filter comprises a filter inductor and a filter capacitor connected in series.

11. The power amplifier circuit according to claim 10, wherein the filter inductor has an inductance of approximately 0.75 nH and the filter capacitor has a capacitance of approximately 14 pF.

12. The power amplifier circuit according to claim 1, wherein the power amplifier comprises:

a phase shift circuit coupled to a power amplifier input node;

a first amplifier stage coupled to the phase shift circuit; and

a second a amplifier stage coupled between the first amplifier stage and the power amplifier output node,

wherein the phase shift circuit, the first amplifier stage, and the second amplifier stage are responsive to the power mode signal.

13. The power amplifier circuit according to claim 12, wherein the phase shift circuit comprises:

a second capacitor coupled between the power amplifier input node and a first internal node;

an inductor coupled between the first internal node and a second internal node;

a third capacitor coupled between the second internal node and the first amplifier stage;

a first diode coupled between the first internal node and ground; and

a second diode coupled between the second internal node and ground,

wherein the power mode signal is input to the first internal node.

14. The power amplifier circuit according to claim 12, wherein the phase shift circuit comprises:

a second capacitor coupled between the power amplifier input node and a first internal node;

an inductor coupled between the first internal node and a second internal node;

a third capacitor coupled between the second internal node and the first amplifier stage;

a fourth capacitor coupled between the first internal node and a third internal node;

a fifth capacitor coupled between the second internal node and the third internal node; and

a third switch coupled between the third internal node and ground,

wherein the third switch is responsive to the power mode signal.

15. The power amplifier circuit according to claim 12, wherein the phase shift circuit is tunable.

16. The power amplifier circuit according to claim 12, wherein:

the first amplifier stage comprises;

a first transistor, having a first transistor base, a first transistor emitter and a first transistor collector; and

a first current mirror circuit configured to stabilize a voltage at the first transistor base, and

the second amplifier stage comprises;

a second transistor, having a second transistor base, a second transistor emitter and a second transistor collector; and

a second current mirror circuit configured to stabilize a voltage at the second transistor base, and

the first and second current mirror circuits are responsive to the power mode signal.

17. The power amplifier circuit according to claim 16, wherein:

the first amplifier stage further comprises;

a first input match circuit coupled between the phase shift circuit and the first transistor base;

a first output match circuit coupled between the first transistor collector and the second amplifier stage; and

an inductor and transmission line connected between a first battery voltage input node and the first transistor collector, and a capacitor connected between said first battery voltage input node and ground,

the second amplifier stage further comprises;

a second input match circuit coupled between the first output match circuit and the second transistor base; and

an inductor and transmission line connected between a second battery voltage input node and the second transistor collector, and a capacitor connected between said second battery voltage input node and ground.

18. A power amplifier circuit, comprising:

a power amplifier responsive to a power mode signal, said power amplifier having a power amplifier output node; and

a power amplifier load circuit also responsive to said power mode signal, said power amplifier load circuit having a load circuit input node connected to said power amplifier output node;

wherein the power amplifier load circuit comprises;

a first transmission line coupled between the load circuit input node and a first node;

a second transmission line coupled between the first node and a second node;

a harmonic filter and a first switch connected to one another in series, between the load circuit input node and ground;

a first capacitor coupled between the first node and a common node;

a second capacitor coupled between the second node and the common node; and

a second switch coupled between the common node and ground,

wherein the first and second switches are responsive to the power mode signal.

19. A power amplifier circuit, comprising:

a power amplifier responsive to a power mode signal, said power amplifier having a power amplifier output node; and

a power amplifier load circuit also responsive to said power mode signal, said power amplifier load circuit having a load circuit input node connected to said power amplifier output node;

wherein the power amplifier load circuit comprises;

a first transmission line coupled between the load circuit input node and a first node;

a second transmission line coupled between the first node and a second node,

a filter and a first switch connected to one another in series, between the load circuit input node and ground;

a first capacitor and a second switch connected to one another in series, between the first node and ground; and

a second capacitor and a third switch connected to one another in series, between the second node and ground;

wherein the first, second and third switches are all responsive to the power mode signal.