Method and Apparatus of an Input Resistance of a Passive Mixer to Broaden the Input Matching Bandwidth of a Common Source/Gate LNA

• US 20180183391A1
• Filed: 01/31/2018
• Published: 06/28/2018
• Est. Priority Date: 12/06/2011
• Status: Active Grant

• Current Assignee: Tensorcom Inc
• Original Assignee: Tensorcom Inc
• Inventors: Soe, Zaw
• Granted Patent: US 10,461,703 B2
• Time in Patent Office: Days
• CPC Class Codes: H03D 7/125 with field effect transistors
• CPC Class Codes: H03D 7/1441 using field-effect transistors H03D7/145 takes precedence
• CPC Class Codes: H03D 7/1466 Passive mixer arrangements
• CPC Class Codes: H03D 7/165 at least two frequency changers being located in different paths, e.g. in two paths with carriers in quadrature combined with amplitude demodulation H03D1/2245, combined with angle demodulation H03D3/007; N-path filters H03H19/002
• CPC Class Codes: H03F 1/223 with MOSFET's
• CPC Class Codes: H03F 1/42 Modifications of amplifiers to extend the bandwidth
• CPC Class Codes: H03F 2200/108 A coil being added in the drain circuit of a FET amplifier stage, e.g. for noise reducing purposes
• CPC Class Codes: H03F 2200/294 the amplifier being a low noise amplifier [LNA]
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 2200/492 A coil being added in the source circuit of a transistor amplifier stage as degenerating element
• CPC Class Codes: H03F 2200/72 the amplifier stage being a common gate configuration MOSFET
• CPC Class Codes: H03F 2200/75 the amplifier stage being a common source configuration MOSFET
• CPC Class Codes: H03F 3/193 with field-effect devices H03F3/195 takes precedence
• CPC Class Codes: H03F 3/387 with semiconductor devices only
• CPC Class Codes: H03F 3/45071 with semiconductor devices only
• CPC Class Codes: H03F 3/45179 using MOSFET transistors as the active amplifying circuit H03F3/45278 takes precedence
• CPC Class Codes: H04L 27/38 Demodulator circuits; Receiver circuits

Abstract

A common-source Low Noise Amplifier (LNA) comprises a first spiral inductor coupled to a source of a first transistor, a second spiral inductor coupled to a drain of a second transistor, and a third inductor connecting the first transistor to the second transistor. The third inductor is configurable to enable a first capacitance to be coupled in parallel to form a bandpass filter. The first spiral inductor is configurable to enable a second capacitance to be coupled in parallel to form a resonant circuit. A variation of the LNA further includes a drain of a third transistor coupled to a gate of a fourth transistor with a first width, a source of the third transistor coupled to the resonant circuit, and an oscillator clock configured to operate at a first frequency that enables the third transistor, wherein the third transistor presents a first impedance to the resonant circuit, causing the resonant circuit to have a first bandwidth.

Claims

1. A common-source Low Noise Amplifier (LNA), comprising:

a first spiral inductor coupled to a source of a first transistor;

a second spiral inductor coupled to a drain of a second transistor; and

a third inductor connecting the first transistor to the second transistor.

2. The common-source LNA of claim 1, wherein the third inductor is configurable to enable a first capacitance to be coupled in parallel to form a bandpass filter;

and the first spiral inductor is configurable to enable a second capacitance to be coupled in parallel to form a resonant circuit.

3. The apparatus of claim 2, wherein the resonant circuit oscillates at a lower frequency than a center frequency when a width of the second transistor is less than a width of the first transistor.

4. The apparatus of claim 2, wherein the resonant circuit oscillates at a higher frequency than a center frequency when a width of the second transistor is greater than a width of the first transistor.

5. The apparatus of claim 1, further comprising:

a drain of a third transistor coupled to a gate of a fourth transistor with a first width;

a source of the third transistor configured to be coupled to the resonant circuit; and

an oscillator clock configured to operate at a first frequency that enables the third transistor;

wherein the third transistor presents a first impedance to the resonant circuit, causing the resonant circuit to have a first bandwidth.

6. The apparatus of claim 5, wherein the resonant circuit has a wider bandwidth than the first bandwidth when either a frequency of the oscillator clock is larger than the first frequency, a width of the fourth transistor is larger than the first width, or both are increased simultaneously.

7. The apparatus of claim 5, wherein the resonant circuit has a narrower bandwidth than the first bandwidth when either a frequency of the oscillator clock is less than the first frequency, a width of the fourth transistor is less than the first width, or both are decreased simultaneously.

8. A method for making a common-source LNA, comprising:

coupling a first spiral inductor to a source of a first transistor;

coupling a second spiral inductor to a drain of a second transistor; and

connecting a third inductor between the first transistor to the second transistor.

9. The method of claim 8, further comprising:

configuring the third inductor to enable coupling a first capacitor in parallel, thereby forming a bandpass filter; and

configuring the second spiral inductor to enable coupling a second capacitor in parallel, thereby forming a resonant circuit.

10. The method of claim 9, wherein the resonant circuit oscillates at a lower frequency than the center frequency when a width of the second transistor is less than a width of the first transistor.

11. The method of claim 9, wherein the resonant circuit oscillates at a higher frequency than the center frequency when a width of the second transistor is greater than a width of the first transistor.

12. The method of claim 9, further comprising:

coupling a drain of a third transistor to a gate of a fourth transistor with a first width;

coupling a source of the third transistor to the resonant circuit; and

configuring an oscillator clock to operate at a first frequency to enable the third transistor; and

presenting a first impedance of the third transistor to the resonant circuit, causing the resonant circuit to have a first bandwidth.

13. The method of claim 12, wherein the resonant circuit has a wider bandwidth than the first bandwidth when either a frequency of the oscillator clock is larger than the first frequency, a width of the fourth transistor is larger than the first width, or both are increased simultaneously.

14. The method of claim 12, wherein the resonate circuit has a narrower bandwidth than the first bandwidth when either a frequency of the oscillator clock is less than the first frequency, a width of the fourth transistor is less than the first width, or both are decreased simultaneously.

15. The method of claim 12, wherein energy from the resonant circuit is used to charge the gate of the fourth transistor.