Variable-gain cascode amplifier using voltage-controlled and variable inductive load

• US 20050140456A1
• Filed: 12/26/2003
• Published: 06/30/2005
• Est. Priority Date: 12/26/2003
• Status: Active Grant

• Current Assignee: Agency For Science Technology and Research
• Original Assignee: Agency For Science Technology and Research
• Inventors: Xiong, Yong Zhong, Krishnasamy Maniam, Nuntha Kumar
• Granted Patent: US 7,019,593 B2
• Time in Patent Office: Days
• US Class Current: 330/311
• CPC Class Codes: H01L 23/5227 Inductive arrangements or effects of, or between, wiring layers other inductive arrangements H01L23/645
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H03F 1/22 by use of cascode coupling, i.e. earthed cathode or emitter stage followed by earthed grid or base stage respectively
• CPC Class Codes: H03F 1/26 Modifications of amplifiers to reduce influence of noise generated by amplifying elements
• 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 2200/541 Transformer coupled at the output of an amplifier
• CPC Class Codes: H03F 3/191 Tuned amplifiers H03F3/193, H03F3/195 take precedence
• CPC Class Codes: H03G 1/0023 in emitter-coupled or cascode amplifiers H03G1/0029 takes precedence
• CPC Class Codes: H03G 1/007 using FET type devices

Abstract

Circuits, such as a cascode amplifier or low noise amplifier, having terminals and a voltage-controlled and variable inductive load are disclosed. Any such circuit comprises an output terminal and a voltage-controlled and variable inductive loading network. The voltage-controlled and variable inductive loading network comprises a primary inductor having a first primary inductor terminal for coupling to a supply voltage, a second primary inductor terminal coupled to the output terminal, a secondary inductor sharing mutual inductance with the first inductor, and a variable resistance device having one terminal connected to a first secondary inductor terminal and another terminal connected to a second secondary inductor terminal, wherein the variable resistance device being dependant on mutual induction between the primary and secondary inductors provides loading at the output terminal.

Claims

1. A variable gain cascode amplifier comprising:

an input transistor having a first output terminal for coupling to a bias current and an input terminal for coupling to an input signal;

a cascode transistor having a first output terminal coupled to a second output terminal of the input transistor and a second output terminal for providing an output signal;

a primary inductor having a first primary inductor terminal for coupling to a supply voltage, a second primary inductor terminal coupled to the second output terminal of the cascode transistor;

a secondary inductor sharing mutual inductance with the first inductor; and

a variable resistance device having one terminal connected to a first secondary inductor terminal and another terminal connected to a second secondary inductor terminal

wherein the variable resistance device being dependant on mutual induction between the primary and secondary inductors provides loading at the second output terminal of the cascode transistor.

2. The amplifier as in claim 1, wherein the variable resistance device comprises at least one circuit element providing variable resistance.

3. The amplifier as in claim 2, wherein the at least one circuit element is a variable resistor.

4. The amplifier as in claim 2, wherein the at least one circuit element is a transistor.

5. The amplifier as in claim 4, wherein the variable resistance device comprises two transistors, the two transistors being configured as two variable resistance transistors including a first variable resistance transistor and a second variable resistance transistor.

6. The amplifier as in claim 5, wherein a first output terminal of the first variable resistance transistor is coupled to the first secondary inductor terminal and a first output terminal of the second variable resistance transistor is coupled to the second secondary inductor terminal.

7. The amplifier as in claim 6, wherein a second output terminal of the first variable resistance transistor is coupled to a second output terminal of the second variable resistance transistor.

8. The amplifier as in claim 6, wherein an input terminal of at least one of the first and second variable resistance transistor is couplable to a control signal for controlling the state of the at least one of the first and second variable resistance transistor.

9. The amplifier as in claim 1, wherein the primary and secondary inductors are on-chip circuit elements, the primary inductor being patterned on a first semiconductor layer and the secondary inductor being patterned on a second semiconductor layer separate from the first semiconductor layer.

10. The amplifier as in claim 9, wherein the mutual inductance shared between the primary and secondary inductors is dependant on electromagnetic coupling between the primary and secondary inductors during operation of the amplifier.

11. The amplifier as in claim 9, wherein the primary and secondary inductors are patterned as spirals.

12. The amplifier as in claim 1, wherein the input and cascode transistors are n-channel depletion-type metal oxide field-effect transistors.

13. A circuit having terminals and a voltage-controlled and variable inductive load, the circuit comprising:

an output terminal; and

a voltage-controlled and variable inductive loading network comprising

a primary inductor having a first primary inductor terminal for coupling to a supply voltage, a second primary inductor terminal coupled to the output terminal;

a secondary inductor sharing mutual inductance with the first inductor, and

a variable resistance device having one terminal connected to a first secondary

inductor terminal and another terminal connected to a second secondary inductor terminal

wherein the variable resistance device being dependant on mutual induction between the primary and secondary inductors provides loading at the output terminal.

14. The circuit as in claim 13, wherein the variable resistance device comprises at least one circuit element providing variable resistance.

15. The circuit as in claim 14, wherein the at least one circuit element is a variable resistor.

16. The circuit as in claim 14, wherein the at least one circuit element is a transistor.

17. The circuit as in claim 16, wherein the variable resistance device comprises two transistors, the two transistors being configured as two variable resistance transistors including a first variable resistance transistor and a second variable resistance transistor.

18. The circuit as in claim 17, wherein a first output terminal of the first variable resistance transistor is coupled to the first secondary inductor terminal and a first output terminal of the second variable resistance transistor is coupled to the second secondary inductor terminal.

19. The circuit as in claim 18, wherein a second output terminal of the first variable resistance transistor is coupled to a second output terminal of the second variable resistance transistor.

20. The circuit as in claim 18, wherein an input terminal of at least one of the first and second variable resistance transistor is couplable to a control signal for controlling the state of the at least one of the first and second variable resistance transistor.

21. The circuit as in claim 13, wherein the primary and secondary inductors are on-chip circuit elements, the primary inductor being patterned on a first semiconductor layer and the secondary inductor being patterned on a second semiconductor layer separate from the first semiconductor layer.

22. The circuit as in claim 21, wherein the mutual inductance shared between the primary and secondary inductors is dependant on electromagnetic coupling between the primary and secondary inductors during operation of the circuit.

23. The circuit as in claim 21, wherein the primary and secondary inductors are patterned as spirals.

24. The circuit as in claim 13, further comprising a cascode amplifier, wherein the cascode amplifier comprises

an input transistor having a first output terminal for coupling to a bias current and an input terminal for coupling to an input signal, and

a cascode transistor having a first output terminal coupled to a second output terminal of the input transistor and a second output terminal for providing an output signal

wherein the second output terminal of the cascode transistor is connected to the output terminal for providing variable gain control to the cascode amplifier.