Systems and methods for controlling the second order intercept point of receivers

• US 8,849,227 B2
• Filed: 09/28/2010
• Issued: 09/30/2014
• Est. Priority Date: 09/28/2009
• Status: Active Grant

• Current Assignee: Trustees Of Columbia University In The City Of New York (Columbia University)
• Original Assignee: Trustees Of Columbia University In The City Of New York (Columbia University)
• Inventors: Feng, Yiping, Kinget, Peter
• Primary Examiner(s): Tsvey, Gennadiy
• Application Number:
  US12/892,888
• Publication Number:
  US 20110076961A1
• Time in Patent Office: 1,463 Days
• Field of Search: 455/67.14, 455/226.1, 329/319, 329/351
• US Class Current: 455/226.1
• CPC Class Codes: H04B 17/0085 using test signal generators
• CPC Class Codes: H04B 17/21 for calibration; for correcting measurements

Abstract

In accordance with some embodiments, methods for controlling the second order intercept point in a receiver are provided, the methods comprising: generating an amplitude modulated test tone; causing the test tone to be received by a receiver; determining a characteristic of a second order intercept point of the receiver based on the received test tone; and based on the characteristic, adjusting a parameter of the receiver. In accordance with some embodiments, systems for controlling the second order intercept point in a receiver are provided, the systems comprising: a test tone generator that generates an amplitude modulated test tone; a receiver that receives the test tone; a correlator that determines a characteristic of a second order intercept point of the receiver based on the received test tone; and digital logic that, based on the characteristic, adjusts a parameter of the receiver.

Claims

1. A method for controlling the second order intercept point in a receiver, comprising:

generating an amplitude modulated test tone based at least in part on a pseudo-random noise sequence;

causing the test tone to be received by a receiver;

applying a first gate bias voltage to a mixer in the receiver;

producing a baseband output using the mixer in the receiver in response to the test tone and the first gate bias voltage;

producing a sign bit by performing a correlation on the baseband output against the pseudo-random noise sequence;

determining whether the sign bit is equal to zero;

generating a first voltage step based on the determination;

generating a second gate bias voltage by combining the first gate bias voltage and the first voltage step;

applying the second gate bias voltage to the mixer;

generating a second voltage step based on the first voltage step;

determining whether the second voltage step is less than a predetermined threshold; and

in response to determining that the second voltage step is less than the predetermined threshold, determining that the second-order intercept point of the receiver converges to an optimal value.

2. The method of claim 1, wherein the amplitude modulated test tone is modulated by the pseudo-random noise sequence.

3. The method of claim 1, wherein the amplitude modulated test tone is generated by combining the pseudo-random noise sequence with a local oscillator signal.

4. The method of claim 1, wherein the receiver is a direct conversion receiver.

5. The method of claim 1, further comprising downconverting the test tone.

6. The method of claim 5, further comprising filtering the downconverted test tone.

7. The method of claim 5, further comprising performing an analog to digital conversion on the downconverted test tone.

8. The method of claim 1, further comprising determining whether the second order intercept point is less than the optimal value.

9. The method of claim 1, further comprising determining whether the second order intercept point is greater than the optimal value.

10. A system for controlling the second order intercept point in a receiver, comprising:

a test tone generator that generates an amplitude modulated test tone based at least in part on a pseudo-random noise sequence;

a receiver that receives the test tone and produces a baseband output using a mixer in the receiver in response to the test tone and a first gate bias voltage applied to the mixer;

a correlator that produces a sign bit by performing a correlation on the baseband output against the pseudo-random sequence; and

digital logic that;

determines whether the sign bit is equal to zero;

generates a first voltage step based on the determination;

generates a second gate bias voltage by combining the first gate bias voltage and the first voltage step;

applies the second gate bias voltage to the mixer;

generates a second voltage step based on the first voltage step;

determines whether the second voltage step is less than a predetermined threshold; and

in response to determining that the second voltage step is less than the predetermined threshold, determines that the second-order intercept point of the receiver converges to an optimal value.

11. The system of claim 10, wherein the test tone generator generates the amplitude modulated test tone such that it is modulated by the pseudo-random noise sequence.

12. The system of claim 10, wherein the test tone generator generates the amplitude modulated test tone by combining the pseudo-random noise sequence with a local oscillator signal.

13. The system of claim 10, wherein the receiver is a direct conversion receiver.

14. The system of claim 10, wherein the receiver downconverts the test tone.

15. The system of claim 14, wherein the receiver filters the downconverted test tone.

16. The system of claim 14, further comprising an analog to digital converter that performs an analog to digital conversion on the downconverted test tone.

17. The system of claim 10, wherein the correlator further determines whether the second order intercept point is less than the optimal value.

18. The system of claim 10, wherein the correlator further determines whether the second order intercept point is greater than the optimal value.

19. The system of claim 10, wherein the digital logic includes a digital to analog converter.