Method and apparatus for amplifying a radio frequency signal

• US 6,404,283 B1
• Filed: 08/18/2000
• Issued: 06/11/2002
• Est. Priority Date: 08/18/2000
• Status: Expired due to Term

• Current Assignee: North Star Innovations Inc. (Wi-LAN Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Lau, Sin Kai Henry, Watanabe, Glenn
• Primary Examiner(s): Pascal, Robert
• Assistant Examiner(s): Nguyen, Patricia T.
• Application Number:
  US09/639,126
• Time in Patent Office: 662 Days
• Field of Search: 330/51, 330/129, 330/133, 330/134, 455/241.1, 455/251.1, 455/253.2
• US Class Current: 330/129
• CPC Class Codes: H03F 1/223 with MOSFET's
• CPC Class Codes: H03F 2203/7236 the gated amplifier being switched on or off by putting into parallel or not, by choosing between amplifiers by (a ) switch(es)
• CPC Class Codes: H03F 3/193 with field-effect devices H03F3/195 takes precedence
• CPC Class Codes: H03F 3/72 Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal
• CPC Class Codes: H03G 1/0023 in emitter-coupled or cascode amplifiers H03G1/0029 takes precedence
• CPC Class Codes: H03G 1/0088 using discontinuously variable devices, e.g. switch-operated

Abstract

The present invention concerns a method for variable linear amplification and an apparatus for a variable linear amplifier, which is particularly suited for RF communication applications. One embodiment includes a high gain circuit in communication with a transconductor to receive an RF signal, a low gain circuit in communication with the transconductor and a current dissipation circuit in communication with the transconductor and a ground source. In one embodiment, the high gain circuit is a NMOS device which is characteristically larger than the low gain device.

Claims

1. A variable gain amplifier in a wireless device having a transconductor including a radio frequency input, a control circuit and an impedance matching circuit having a radio frequency output, the amplifier comprising:

a) a high gain circuit in communication with the transconductor and the impedance matching circuit, the high gain circuit controlled by the control circuit;

b) a low gain circuit in communication with the transconductor, the high gain circuit and the impedance matching circuit, the low gain circuit controlled by the control circuit; and

c) a controllable current dissipation circuit in communication with the transconductor, a ground source and the impedance matching circuit.

2. The variable gain amplifier of claim 1 wherein the controllable current dissipation circuit is controlled by and in communication with a dissipation control means.

3. The variable gain amplifier of claim 2 wherein the transconductor is a power to current conversion circuit.

4. The variable gain amplifier of claim 3 further including at least one gain circuit in communication with the high gain circuit, the low gain circuit and the current dissipation circuit.

5. The variable gain amplifier of claim 4 wherein the high gain circuit NMOS device characteristically including WG=16 microns, LG=0.4 micron and NG=16 gates.

6. The variable gain amplifier of claim 5 wherein the low gain circuit is a NMOS device characteristically including WG=16 microns, LG=0.4 micron and NG=3 gates.

7. The variable gain amplifier of claim 5 wherein the current dissipation circuit is a NMOS device characteristically including NG=64 gates, LG=0.4 micron and WG=16 microns.

8. A variable gain amplifier comprising:

a) a transconductor having a radio frequency input;

b) a high gain circuit in communication with the transconductor and controlled by a control circuit;

c) a low gain circuit in communication with the transconductor and high gain circuit, the low gain circuit controlled by the control circuit;

d) a current dissipation circuit in communication with the transconductor and a ground source;

e) a dissipation control means for controlling the current dissipation circuit, the dissipation control means in communication with the current dissipation circuit; and

f) an impedance matching circuit in communication with the high gain circuit, the low gain circuit and the current dissipation circuit, the impedance matching circuit having an RF output.

9. The variable gain amplifier of claim 8 wherein the high gain circuit is a high gain common gate amplifier NMOS device.

10. The variable gain amplifier of claim 8 wherein the low gain circuit is a low gain common gate amplifier NMOS device.

11. The variable gain amplifier of claim 8 further including a plurality of variable gain circuits in communication with the high gain circuit, the low gain circuit and the current dissipation circuit.

12. A method for providing linear amplification to a radio frequency (RF) signal received by a wireless device from an RF transmitting source, the wireless device having a transconductor including a radio frequency input, a control circuit and an impedance matching circuit having a radio frequency output, the method comprising the steps of:

a) introducing a high gain circuit in communication with the transconductor and the impedance matching circuit, the high gain circuit controlled by the control circuit;

b) introducing a low gain circuit in communication with the transconductor, the high gain circuit and the impedance matching circuit, the low gain circuit controlled by the control circuit; and

c) introducing a controllable current dissipation circuit in communication with the transconductor, a ground source and the impedance matching circuit, the controllable current dissipation circuit being controlled by and in communication with a dissipation control means.

13. The method for providing linear amplification of claim 12 further including at least one gain circuit in communication with the high gain circuit, the low gain circuit and the current dissipation circuit.

14. A method for achieving variable linear amplification in radio frequency (RF) applications comprising the steps of:

a) introducing a transconductor having an RF input bus;

b) providing a controllable high gain circuit and a controllable low gain circuit in communication with the transconductor, the high gain circuit in communication with the low gain circuit, the high gain and low gain having a common RF output bus;

c) providing a controllable current dissipation circuit in communication with the transconductor and a ground source, the controllable current dissipation circuit further in communication with a ground source;

d) providing a current dissipation controller in communication with the current dissipation circuit;

e) transconducting an RF input signal by the transconductor;

f) amplifying the RF signal through the high gain circuit when the RF input signal originates from a far RF transmitting source and outputting a high gain RF output signal to the processing circuitry;

g) amplifying the RF signal through the low gain circuit when the RF input signal originates from a nearby RF transmitting source, allowing a portion of the RP signal current to be dissipated by the current dissipation circuit, and outputting a low gain RF output signal to the processing circuitry.

15. The method for achieving variable linear amplification of claim 14 further including a plurality of variable gain circuits in communication with the high gain circuit, the low gain circuit and the current dissipation circuit.

16. A method for amplifying a radio frequency (RF) signal comprising the steps of:

a) transconducting the RF signal resulting in a transconductance signal;

b) amplifying the transconductance signal through a first controllable circuit when the RF signal originates from a far away RF transmitting source resulting in a high gain RF output signal and transmitting the high gain RF output signal to processing circuitry; and

c) amplifying a desired portion of the transconductance signal through a second controllable circuit when the RF signal originates from a nearby RF transmitting source resulting in a low gain RF output signal, transmitting an undesired portion of the transconductance signal through a third controllable circuit and transmitting the low gain RF output signal to processing circuitry.

17. The method for amplifying a RF signal of claim 16 wherein the high gain circuit is a high gain common gate amplifier NMOS device.

18. The method for amplifying an RF signal of claim 16 wherein the low gain circuit is a low gain common gate amplifier NMOS device.

19. The method for amplifying an RF signal of claim 16 further including a plurality of variable gain circuits in communication with the high gain circuit, the low gain circuit and the third controllable circuit, the third controllable circuit further including a current dissipation circuit.

20. The method for amplifying an RF signal of claim 19 wherein the current dissipation circuit is a common gate amplifier NMOS device.