Electrically tuned integrated amplifier for wireless communications

• US 6,509,799 B1
• Filed: 11/09/2000
• Issued: 01/21/2003
• Est. Priority Date: 11/09/2000
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Franca-Neto, Luiz M.
• Primary Examiner(s): Pascal, Robert
• Assistant Examiner(s): Choe, Henry
• Application Number:
  US09/711,332
• Time in Patent Office: 803 Days
• Field of Search: 330/292, 330/305, 330/311, 330/306, 334/15
• US Class Current: 330/305
• CPC Class Codes: H03F 1/223 with MOSFET's
• CPC Class Codes: H03F 2200/294 the amplifier being a low noise amplifier [LNA]
• CPC Class Codes: H03F 2200/372 Noise reduction and elimination in amplifier
• CPC Class Codes: H03F 2200/391 the output circuit of an amplifying stage comprising an LC-network
• CPC Class Codes: H03F 2203/45704 the LC comprising one or more parallel resonance circuits
• CPC Class Codes: H03F 3/193 with field-effect devices H03F3/195 takes precedence
• CPC Class Codes: H03F 3/45188 Non-folded cascode stages

Abstract

An electrically tunable radio frequency (RF) amplifier includes a resonant circuit having a voltage variable capacitance as one of its elements. In one approach, a drain diffusion capacitance of one of the transistors within the amplifier is used as the voltage variable capacitance. A voltage adjustment unit is provided to adjust a bias voltage on the voltage variable capacitance to change the capacitance value thereof and thus modify the operating frequency range of the amplifier. In one embodiment, the voltage adjustment unit also provides a power supply noise blocking function.

Claims

1. A radio frequency (RF) amplifier comprising:

a resonant circuit having a plurality of circuit elements, said plurality of circuit elements including a voltage variable capacitance, said resonant circuit having a resonant frequency that depends upon a present value of said voltage variable capacitance; and

a voltage adjustment unit in communication with said voltage variable capacitance to vary a bias voltage on said voltage variable capacitance to modify a capacitance value thereof;

wherein said voltage variable capacitance is a diffusion capacitance associated with a first transistor within the RF amplifier, and wherein said voltage adjustment unit includes a third transistor having an input terminal to receive a control signal, said third transistor to vary a voltage drop between a supply node and said first transistor in response to variations in said control signal.

2. The RF amplifier claimed in claim 1, wherein:

said first transistor is biased in saturation during operation of the RF amplifier.

3. The RF amplifier claimed in claim 1, wherein said first transistor is part of a cascode core within said RF amplifier.

4. The RF amplifier claimed in claim 1, comprising:

an output terminal to deliver an amplified signal to other circuitry, said first transistor being connected to said output terminal.

5. The RF amplifier claimed in claim 1, comprising:

a second transistor connected between said first transistor and a ground node, said second transistor having an input terminal to receive an RF input signal to be amplified by said RF amplifier.

6. The RF amplifier claimed in claim 1, wherein:

said first transistor includes an input terminal to receive an RF input signal to be amplified by said RF amplifier.

7. The RF amplifier claimed in claim 1, wherein:

said voltage adjustment unit is connected between said resonant circuit and a supply node.

8. The RF amplifier claimed in claim 1, wherein:

said RF amplifier further includes control circuitry coupled to said input terminal of said third transistor to generate said control signal.

9. The RF amplifier claimed in claim 8, wherein:

said control circuitry includes circuitry for tuning an operational frequency range of said RF amplifier using said control signal.

10. The RF amplifier claimed in claim 8, wherein:

said control circuitry includes circuitry for automatically tuning an operational frequency range of said RF amplifier in the field to compensate for component aging.

11. The RF amplifier claimed in claim 1, wherein:

said resonant circuit and said voltage adjustment unit are integrated on a common semiconductor chip.

12. The RF amplifier claimed in claim 11, further comprising:

an integrated circuit package housing said common semiconductor chip, said integrated circuit package having a first pin connected to a supply node on said chip to connect said RF amplifier to an external power supply, a second pin connected to a ground node on said chip to connect said RF amplifier to an external ground, and a third pin connected to the input terminal of said third transistor to connect said RF amplifier to an external control signal source.

13. A radio frequency (RF) amplifier comprising:

an output node to carry an output signal;

a resonant circuit connected to said output node;

at least one transistor coupled between said output node and a ground node, said at least one transistor including a first transistor connected to said output node, said first transistor having a voltage variable diffusion capacitance; and

a voltage adjustment unit in communication with said output node to adjust a bias voltage thereon to change a capacitance value of said voltage variable diffusion capacitance of said first transistor to adjust a resonant frequency of said RF amplifier;

wherein said voltage adjustment unit includes a transistor coupled between a supply node and said output node, said transistor including an input terminal to receive a control signal.

14. The RF amplifier of claim 13, wherein:

said first transistor is biased in saturation during operation of said RF amplifier.

15. The RF amplifier of claim 13, wherein:

said voltage adjustment unit adjusts said bias voltage on said output node in response to said control signal.

16. The RF amplifier of claim 13, wherein:

said transistor connected between said supply node and said output node is biased in saturation during operation of said RF amplifier.

17. The RF amplifier of claim 13, wherein:

said at least one transistor includes a cascode core having said first transistor connected to said output node and a second transistor coupled between said first transistor and said ground node, said second transistor having an input terminal to receive an input signal to be amplified by said RF amplifier.

18. The RF amplifier of claim 13, wherein:

said at least one transistor is connected directly to said ground node.

19. A radio frequency (RF) amplifier comprising:

a resonant circuit having a plurality of circuit elements, said plurality of circuit elements including a voltage variable capacitance, said resonant circuit having a resonant frequency that depends upon a present value of said voltage variable capacitance; and

a voltage adjustment unit in communication with said voltage variable capacitance to vary a bias voltage on said voltage variable capacitance to modify a capacitance value thereof;

wherein said voltage adjustment unit includes an input port to receive a control signal, said RF amplifier further including control circuitry coupled to said input port of said voltage adjustment unit to generate said control signal, said control circuitry including circuitry for automatically tuning an operational frequency range of said RE amplifier in the field to compensate for component aging.

20. The RF amplifier of claim 19, wherein:

said voltage variable capacitance is a voltage variable diffusion capacitance of a transistor within the RF amplifier.

21. The RF amplifier of claim 20, wherein:

said transistor is biased in saturation during operation of said RF amplifier.

22. A radio frequency (RF) amplifier comprising:

a resonant circuit having a plurality of circuit elements, said plurality of circuit elements including a voltage variable capacitance, said resonant circuit having a resonant frequency that depends upon a present value of said voltage variable capacitance; and

a voltage adjustment unit in communication with said voltage variable capacitance to vary a bias voltage on said voltage variable capacitance to modify a capacitance value thereof;

wherein said resonant circuit and said voltage adjustment unit are integrated on a common semiconductor chip, said RF amplifier further comprising an integrated circuit package housing said common semiconductor chip, said integrated circuit package having a first pin connected to a supply node on said chip to connect said RF amplifier to an external power supply, a second pin connected to a ground node on said chip to connect said RF amplifier to an external ground, and a third pin connected to an input terminal of said voltage adjustment unit to connect said RF amplifier to an external control signal source.

23. The RF amplifier of claim 22, wherein:

said voltage variable capacitance is a voltage variable diffusion capacitance of a transistor within the RF amplifier.

24. The RF amplifier of claim 23, wherein:

said transistor is biased in saturation during operation of said RF amplifier.

25. The RF amplifier of claim 23, wherein:

said transistor is part of a cascode core.

26. The RF amplifier of claim 22, wherein:

said voltage adjustment unit includes a transistor coupled between a supply node and said voltage variable capacitance, said transistor having an input terminal to receive a control signal.

27. The RF amplifier of claim 26, wherein:

said transistor is biased in saturation during operation of said RF amplifier.