Divided-voltage fet power amplifiers

• US 6,683,499 B2
• Filed: 12/20/2001
• Issued: 01/27/2004
• Est. Priority Date: 12/27/2000
• Status: Expired due to Fees

• Current Assignee: Emhiser Research Inc
• Original Assignee: Emhiser Research Inc
• Inventors: Lautzenhiser, Lloyd L., Lautzenhiser, Barry A.
• Primary Examiner(s): Choe, Henry
• Application Number:
  US10/028,844
• Publication Number:
  US 20020113655A1
• Time in Patent Office: 768 Days
• Field of Search: 330/295, 330/286, 330/277, 330/124.R, 330/84
• US Class Current: 330/295
• CPC Class Codes: H03F 1/301 in MOSFET amplifiers H03F1/303, H03F1/305, H03F1/308 take precedence
• CPC Class Codes: H03F 3/601 using FET's, e.g. GaAs FET's H03F3/607, H03F3/608 take precedence

Abstract

Divided-voltage FET amplifiers (10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 130, 140, 150, 160, 170, 180, 200, or 220) include two or more solid-state current devices, preferably gallium arsenide FETs, (Q1, Q2, Q4, Q5, Q6, and/or Q8), connected in series or series-parallel for dc operation, and connected in parallel for rf operation, thereby improving power efficiency by using the same current two or more times to develop rf power. Various ones of the embodiments produce separate rf outputs, separately amplify two rf outputs and subsequently combine them into a single rf output, and/or selectively phase shift rf outputs. Isolation between rf frequencies and dc voltages includes using decoupling capacitors with selected resonant frequencies and low effective series resistances (ESRs) and using inductors with selected self-resonant frequencies for rf chokes. Preferably, providing low ESRs includes paralleling two or more decoupling capacitors (Ca-n) with low ESRs, whose resonant frequencies can be distributed for wide-band operation.

Claims

1. A method for rf power amplifying which comprises:

a) series connecting upper and lower solid-state current devices;

b) said series connecting comprises connecting a lower-voltage terminal of said upper solid-state current device to an rf choke, and connecting said rf choke to a higher-voltage terminal of said lower solid-state current device;

c) separately amplifying rf signals in said solid-state current devices with an rf output of said upper solid-state current device exceeding about 100 milliwatts;

d) said separate amplifying comprises rf amplifying in said upper solid-state current device at a selected operating frequency of one gigahertz or greater;

e) rf decoupling said solid-state current devices;

f) said rf decoupling comprises connecting capacitors in parallel between said lower-voltage terminal and an electrical ground; and

g) said rf decoupling further comprises making said capacitors function as paralleled capacitors.

4. A method as claimed in claim 1 which said method further comprises:

a) splitting an rf input into said rf signals prior to said separate amplifying step; and

b) combining said separately amplified rf signals.

5. A method as claimed in claim 1 in which said rf decoupling further comprises selecting two of said capacitors to resonate at substantially the same frequency.

6. A method as claimed in claim 1 in which said rf decoupling further comprises:

a) selecting one of said capacitors to resonate at a frequency that is higher than said selected operating frequency; and

b) selecting an other of said capacitors to resonate at a frequency that is lower than said selected operating frequency.

7. A method as claimed in claim 1 in which said rf decoupling further comprises:

a) selecting two of said capacitors to resonate at frequencies that are higher than said selected operating frequency; and

b) selecting an other two of said capacitors to resonate at frequencies that are lower than said selected operating frequency.

8. A method as claimed in claim 1 in which said rf decoupling further comprises:

a) selecting two of said capacitors to resonate at separate frequencies that are both higher than said selected operating frequency; and

b) selecting an other two of said capacitors to resonate at separate frequencies that are both lower than said selected operating frequency.

9. A method as claimed in claim 1 in which said paralleling step comprises making an rf effective series resistance of a capacitance less than that of any porcelain capacitor that resonates at said selected operating frequency.

10. A method as claimed in claim 1 in which:

a) disposing said selected operating frequency within a broad band of operating frequencies;

b) said rf decoupling further comprises selecting a first plurality of said capacitors to resonate in a higher-frequency portion of said broad band; and

c) said rf decoupling still further comprises selecting a second plurality of said capacitors to resonate in a lower-frequency portion of said broad band.

11. A method as claimed in claim 1 in which:

a) disposing said selected operating frequency within a broad band of operating frequencies;

b) said rf decoupling further comprises making an rf effective series resistance of a capacitance less than that of any porcelain capacitor that resonates in a higher-frequency of said broad band; and

c) said rf decoupling still further comprises making an rf effective series resistance of a capacitance less than that of any porcelain capacitor that resonates in a lower-frequency of said broad band.

12. A method as claimed in claim 1 in which:

a) disposing said selected operating frequency within a broad band of operating frequencies; and

b) said rf decoupling comprises making an rf effective series resistance between said series connection of said solid-state current devices and an electrical ground less than 0.4 ohms divided by said rf output in watts throughout said broad band.

13. A method as claimed in claim 1 in which:

a) said rf power amplifying comprises series connecting a third solid-state current device with said upper and lower solid-state current devices;

b) said method further comprises supplying a variable voltage to a control terminal of said third solid-state current device; and

c) said method still further comprises controlling said rf output as a function of said variable voltage.

14. A method as claimed in claim 1 in which:

a) said separate amplifying comprises rf amplifying one of said rf signals at varying frequencies; and

b) said method comprises flattening said rf output of said one amplified rf signal with respect to said varying frequencies.

15. A method as claimed in claim 1 in which:

a) said method comprises series connecting a third solid-state current device with said upper and lower solid-state current devices;

b) said separate amplifying comprises amplifying said rf signals at equal and varying frequencies;

c) said method further comprises combining said separately amplified rf signals into a single rf output;

d) said method still further comprises flattening said single rf output with respect to said varying frequencies; and

e) said flattening step comprises detecting said single rf output, using said detected rf output to control said third solid-state current device, and using said third solid-state current device to control said separate amplifying.

16. A method as claimed in claim 1 in which:

a) said method comprises series connecting a third solid-state current device with said upper and lower solid-state current devices;

b) increasing current flow through two of said solid-state current devices with respect to said current flow through an other of said solid-state current devices; and

c) said increasing step comprises shunting current flow around said other solid-state current device.

17. A method as claimed in claim 1 in which said method comprises:

a) series connecting a third solid-state current device with said upper and lower solid-state current devices;

b) amplifying an rf input in said third solid-state current device; and

c) splitting said amplified rf input into said rf signals.

18. A method as claimed in claim 1 in which said method comprises:

a) series connecting third and fourth solid-state current devices with said upper and lower solid-state current devices;

b) amplifying an rf input in said third solid-state current device;

c) splitting said amplified rf input into said rf signals;

d) supplying a variable voltage to a control terminal of said third solid-state current device; and

e) controlling power amplification of said upper and lower solid-state current devices as a function of said variable voltage.

19. A method as claimed in claim 1 in which said method comprises:

a) connecting third and fourth solid-state current devices in parallel; and

b) connecting said parallel-connected third and fourth solid-state current devices in series with said upper and lower solid-state current devices.

20. A method as claimed in claim 1 in which said method comprises:

a) connecting third and fourth solid-state current devices in parallel;

b) connecting said parallel-connected third and fourth solid-state current devices in series with said upper and lower solid-state current devices;

c) amplifying an rf input in said third solid-state current device;

d) splitting said amplified rf input into said rf signals;

e) delivering a variable control voltage to said fourth solid-state current device; and

f) controlling said separate amplifying as a function of said variable control voltage.

21. A method as claimed in claim 1 in which:

a) said method comprises splitting an rf input into said rf signals; and

b) said separate amplifying comprises producing separate rf outputs.

22. A method as claimed in claim 1 in which:

a) said method comprises splitting an rf input into said rf signals;

b) said separate amplifying comprises producing separate rf outputs; and

c) said method further comprises separately phase-shifting one of said separate rf outputs.

23. A method as claimed in claim 1 in which said method further comprises:

a) splitting an rf input into said rf signals and a third rf signal; and

b) separately amplifying said third rf signal.

24. A method as claimed in claim 1 in which said method further comprises:

a) splitting an rf input into said rf signals and a third rf signal;

b) separately amplifying said third rf signal; and

c) combining all of said separately amplified rf signals.

25. A method as claimed in claim 1 in which:

a) said method comprises series connecting a third solid-state current device with said upper and lower solid-state current devices;

b) supplying a variable-voltage input to said third solid-state current device;

c) producing a variable-frequency rf signal in said third solid-state current device that is a function of said variable-voltage input; and

d) splitting said variable-frequency rf signal into said rf signals.

26. A method as claimed in claim 1 in which said method comprises paralleling a third solid-state current device with one of said series-connected solid-state current devices.

27. A method as claimed in claim 1 in which:

a) said method further comprises rf decoupling a lower-voltage terminal of said lower solid-state current device;

b) said rf decoupling comprises providing a capacitance between said lower-voltage terminal of said lower solid-state current device and said electrical ground; and

c) said providing comprises making capacitors function in parallel.

28. A method as claimed in claim 1 in which:

a) said method further comprises rf decoupling a lower-voltage terminal of said lower solid-state current device; and

b) said rf decoupling comprises making an effective series resistance between said lower-voltage terminal and said ground less than that of any porcelain capacitor that resonates at said operating frequency.

2. A method for rf power amplifying which comprises:

a) series connecting upper and lower FETs;

b) said series connecting comprises connecting a source terminal of said upper FET to an rf choke, and connecting said rf choke to a drain terminal of said lower FET;

c) separately amplifying rf signals in said FETs with an rf output of one of said FETs exceeding about 100 milliwatts;

d) said separate amplifying comprises rf amplifying in said upper FET at a selected operating frequency of one gigahertz or greater;

e) rf decoupling said FETs;

f) said rf decoupling comprises providing a capacitance between said source terminal and an electrical ground;

g) said providing comprises achieving an rf effective series resistance of said capacitance that is less than that of any porcelain capacitor that resonates at said selected operating frequency; and

h) said providing and achieving comprises making two capacitors function as paralleled capacitors.

3. A method for rf power amplifying which comprises:

a) series connecting upper and lower solid-state current devices;

b) said series connecting comprises connecting a lower-voltage terminal of said upper solid-state current device to an rf choke, and connecting said rf choke to a higher-voltage terminal of said lower solid-state current device;

c) separately amplifying rf signals in said solid-state current devices with an rf output of said upper solid-state current device exceeding about 100 milliwatts;

d) said separate amplifying comprises rf amplifying in said upper solid-state current device at a selected operating frequency of one gigahertz or greater;

e) rf decoupling said solid-state current devices;

f) said rf decoupling comprises providing a capacitance between said lower-voltage terminal and an electrical ground; and

g) said rf decoupling further comprises making an rf effective series resistance of said capacitance lower than that of any porcelain capacitor that resonates at said selected operating frequency.