NOISE CANCELLING BASEBAND AMPLIFIER

• US 20180026584A1
• Filed: 10/02/2017
• Published: 01/25/2018
• Est. Priority Date: 10/06/2015
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Park, Joung Won, Kim, Namsoo
• Granted Patent: US 10,305,431 B2
• Time in Patent Office: Days
• CPC Class Codes: H03F 1/26 Modifications of amplifiers to reduce influence of noise generated by amplifying elements
• CPC Class Codes: H03F 2200/135 there being a feedback over one or more internal stages in the global amplifier
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 2203/45138 Two or more differential amplifiers in IC-block form are combined, e.g. measuring amplifiers
• CPC Class Codes: H03F 2203/45528 the FBC comprising one or more passive resistors and being coupled between the LC and the IC
• CPC Class Codes: H03F 3/19 with semiconductor devices only
• CPC Class Codes: H03F 3/45071 with semiconductor devices only
• CPC Class Codes: H03F 3/45475 using IC blocks as the active amplifying circuit
• CPC Class Codes: H03F 3/68 Combinations of amplifiers, e.g. multi-channel amplifiers for stereophonics power amplifiers using a combination of several semiconductor amplifiers H03F3/211; combinations of amplifiers using coupling networks with distributed constants H03F3/602

Abstract

An apparatus includes a first amplifier having a first feedback resistance and an output configured to be coupled to a first input of a second amplifier having a second feedback resistance. The apparatus includes a third amplifier coupled to an input of the first amplifier and having an output configured to be coupled to a second input of the second amplifier.

Claims

1. An apparatus comprising:

a low noise amplifier;

a mixer coupled to the low noise amplifier;

a first differential amplifier having a first input configured to receive an input signal from the mixer and having an output configured to be coupled to an inverting input of a second differential amplifier; and

a single-ended amplifier having an input coupled to the first input of the first differential amplifier and having an output configured to be coupled to a non-inverting input of the second differential amplifier, the single-ended amplifier configured to receive the input signal.

2. The apparatus of claim 1, wherein the first differential amplifier is coupled to a first feedback resistor, wherein the second differential amplifier is coupled to a second feedback resistor, and wherein the single-ended amplifier has a gain based on a first feedback resistance of the first feedback resistor and a second feedback resistance of the second feedback resistor.

3. The apparatus of claim 2, wherein the gain is further based on an input resistance to the first differential amplifier and an input resistance to the second differential amplifier.

4. The apparatus of claim 1, wherein the first differential amplifier includes a trans-impedance amplifier, wherein the first input of the first differential amplifier comprises an inverting input, and wherein the first differential amplifier has a non-inverting input coupled to ground.

5. The apparatus of claim 1, wherein the second differential amplifier comprises a programmable baseband amplifier.

6. The apparatus of claim 2, wherein the gain of the single-ended amplifier is less than a gain of the first differential amplifier.

7. The apparatus of claim 1, wherein the single-ended amplifier is configured to amplify a flicker noise signal from the first differential amplifier.

8. The apparatus of claim 7, wherein the second differential amplifier is configured to cancel flicker noise from the first differential amplifier based on the amplified flicker noise signal from the single-ended amplifier.

9. An apparatus comprising:

means for amplifying low noise signals;

means for mixing signals, the means for mixing coupled to the means for amplifying; and

means for filtering received signals, the means for filtering coupled to the means for mixing, and the means for filtering comprising;

first means for amplifying including a first input configured to receive an input signal and including an output configured to be coupled to an inverting input of second means for amplifying; and

third means for amplifying including an input coupled to the first input of the first means for amplifying and including an output coupled to a non-inverting input of the second means for amplifying, the third means for amplifying configured to receive the input signal.

10. The apparatus of claim 9, wherein the third means for amplifying has a gain based on a first means for resisting associated with the first means for amplifying and second means for resisting associated with the second means for amplifying.

11. The apparatus of claim 10, wherein the first means for amplifying is coupled, via a third means for resisting, to the inverting input of the second means for amplifying.

12. The apparatus of claim 9, wherein the first means for amplifying comprises means for trans-impedance amplifying.

13. The apparatus of claim 9, wherein the second means for amplifying comprises means for programmably amplifying a baseband signal.

14. The apparatus of claim 9, wherein the third means for amplifying has a gain that is less than a gain of the first means for amplifying.

15. The apparatus of claim 9, wherein the third means for amplifying is configured to amplify a flicker noise signal at the first input of the first means for amplifying.

16. The apparatus of claim 15, wherein the second means for amplifying includes means for canceling flicker noise from the first means for amplifying based on the amplified flicker noise signal from the third means for amplifying.

17. A method of processing signals, the method comprising:

performing, at a low noise amplifier, a low noise amplification operation on a signal to generate an input signal;

amplifying the input signal at a first differential amplifier to produce a first amplified signal that is provided to an inverting input of a second differential amplifier;

amplifying the input signal at a single-ended amplifier to produce a flicker noise canceling signal that is provided to a non-inverting input of the second differential amplifier, wherein the single-ended amplifier receives the input signal at an input coupled to a first input of the first differential amplifier; and

amplifying the first amplified signal and the flicker noise canceling signal at the second differential amplifier to produce an output signal.

18. The method of claim 17, further comprising mixing the input signal prior to amplifying the input signal at the first differential amplifier and at the single-ended amplifier.

19. The method of claim 17, wherein the input of the single-ended amplifier further receives a flicker noise signal from the first differential amplifier.

20. The method of claim 19, further comprising amplifying the flicker noise signal at the single-ended amplifier to produce the flicker noise canceling signal.