Automatic gain control for enhanced bit error rate performance

• US 8,175,562 B2
• Filed: 10/27/2006
• Issued: 05/08/2012
• Est. Priority Date: 10/27/2006
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Agere Systems Incorporated (Broadcom, Inc.)
• Inventors: Fratti, Roger A., Wang, Xiao-an
• Primary Examiner(s): Nguyen, Duc
• Assistant Examiner(s): CHOW, CHARLES CHIANG
• Application Number:
  US11/553,635
• Publication Number:
  US 20080102774A1
• Time in Patent Office: 2,020 Days
• Field of Search: 455/234.1, 455/424, 455/425, 455/456.5, 455/456.6, 455/561, 455/550.1, 455/575.1, 455/67.11, 455/200.1, 455/232.1, 4552342-2532, 330/278, 330/279, 330/9, 330/306, 375/345, 375/267, 327/179
• US Class Current: 455/238.1
• CPC Class Codes: H03G 3/3068 Circuits generating control signals for both R.F. and I.F. stages

Abstract

An apparatus including automatic gain control (AGC) includes at least one variable gain amplifier (VGA) operative to receive an input signal and to generate an amplified signal. A gain of the VGA is controlled as a function of at least a first control signal. The apparatus further includes an AGC circuit coupled to the VGA and being operative to generate the first control signal. The AGC circuit has a bandwidth that is controlled as a function of at least the amplified signal and a second control signal, the second control signal being indicative of a motion of the apparatus.

Claims

1. An apparatus including automatic gain control (AGC), the apparatus comprising:

at least one variable gain amplifier (VGA) operative to receive an input signal and to generate an amplified signal, a gain of the VGA being controlled as a function of at least a first control signal; and

an AGC circuit coupled to the VGA and being operative to generate the first control signal as a function of at least the amplified signal, the AGC circuit having a bandwidth that is controlled as a function of at least a second control signal such that the bandwidth is independent of the amplified signal;

wherein the AGC circuit is operative to receive the second control signal, the second control signal being indicative of a motion of the apparatus.

2. The apparatus of claim 1, wherein the apparatus comprises a bandwidth control circuit operative to measure a motion of the apparatus and to generate the second control signal as a function of the motion of the apparatus.

3. The apparatus of claim 2, wherein the bandwidth control circuit comprises:

a motion sensor operative to convert a motion of the apparatus into a first signal indicative of the motion of the apparatus;

a transducer coupled to the motion sensor, the transducer being operative to receive the first signal and to generate a voltage signal indicative of the first signal; and

an integrator coupled to the transducer, the integrator being operative to receive the voltage signal and to generate the second control signal.

4. The apparatus of claim 3, wherein the motion sensor is operative to measure at least one of a rate of change of position of the apparatus, a location of the apparatus, and a displacement of the apparatus relative to a fixed object.

5. The apparatus of claim 3, wherein the motion sensor is operative to measure at least one of a rate of change of position of the apparatus, a location of the apparatus, and a displacement of the apparatus relative to a reference speed.

6. The apparatus of claim 3, wherein the transducer comprises a Hall-effect accelerometer.

7. The apparatus of claim 3, wherein the integrator comprises an operational amplifier and at least one capacitive element connected to the amplifier in a feedback configuration.

8. The apparatus of claim 1, wherein the second control signal is generated independently of the input signal.

9. The apparatus of claim 1, wherein the AGC circuit comprises:

an amplifier operative to receive at least one signal that is indicative of the amplified signal and to generate a second amplified signal as a function thereof; and

a low-pass filter having substantially unity gain and having a frequency response that is controllable as a function of the second control signal, the filter being operative to receive the second amplified signal and the second control signal and to generate, as an output thereof, the first control signal.

10. The apparatus of claim 9, wherein the low-pass filter comprises a transconductance-capacitance (g_m-C) filter, a frequency response of the g_m-C filter being controllable as a function of a current in the g_m-C filter, the current in the g_m-C filter being a function of the second control signal.

11. The apparatus of claim 9, wherein the low-pass filter comprises a switched capacitor filter circuit, a frequency response of the switched capacitor filter circuit being controlled as a function of a sampling rate of the switched capacitor filter circuit, the sampling rate of the switched capacitor filter circuit being a function of the second control signal.

12. The apparatus of claim 9, wherein the low-pass filter comprises a capacitor matrix including a plurality of capacitors, a frequency response of the capacitor matrix being controlled as a function of a connection arrangement of the plurality of capacitors in the capacitor matrix, the connection arrangement being a function of the second control signal.

13. The apparatus of claim 9, wherein the low-pass filter comprises a finite impulse response (FIR) filter, a frequency response of the FIR filter being controlled as a function of respective values of one or more FIR filter coefficients, the values of the FIR filter coefficients being a function of the second control signal.

14. The apparatus of claim 1, wherein the VGA comprises at least one low-noise amplifier (LNA) circuit and at least one VGA circuit coupled to the LNA circuit, the LNA circuit including an input adapted to receive the input signal, the LNA being operative to generate a second signal at an output of the LNA circuit, the VGA circuit including an input adapted to receive the second signal from the LNA circuit, the VGA circuit being operative to generate the amplifier output signal at an output of the VGA circuit.

15. The apparatus of claim 1, further comprising at least one analog-to-digital converter (ADC) coupled to the at least one VGA, the ADC being operative to receive the amplified signal and to generate a digital signal indicative of the amplified signal.

16. The apparatus of claim 1, wherein the apparatus is a terminal of a communication system.

17. An integrated circuit including at least one automatic gain control (AGC) system, the at least one AGC system comprising:

at least one variable gain amplifier (VGA) operative to receive an input signal and to generate an amplified signal, a gain of the VGA being controlled as a function of at least a first control signal; and

an AGC circuit coupled to the VGA and being operative to generate the first control signal as a function of at least the amplified signal, the AGC circuit having a bandwidth that is controlled as a function of at least a second control signal such that the bandwidth is independent of the amplified signal;

wherein the AGC circuit is operative to receive the second control signal, the second control signal being indicative of a motion of the AGC system.

18. The integrated circuit of claim 17, wherein the AGC system comprises a bandwidth control circuit operative to measure a motion of the AGC system and to generate the second control signal as a function of the motion of the AGC system.

19. The integrated circuit of claim 18, wherein the bandwidth control circuit comprises:

a motion sensor operative to convert a motion of the apparatus into a first signal indicative of the motion of the apparatus;

a transducer coupled to the motion sensor, the transducer being operative to receive the first signal and to generate a voltage signal indicative of the first signal; and

an integrator coupled to the transducer, the integrator being operative to receive the voltage signal and to generate the second control signal.

20. The integrated circuit of claim 17, wherein the second control signal is generated independently of the input signal.

21. The integrated circuit of claim 17, wherein the AGC circuit comprises:

an amplifier operative to receive at least one signal that is indicative of the amplified signal and to generate a second amplified signal as a function thereof; and

a low-pass filter having substantially unity gain and having a frequency response that is controllable as a function of the second control signal, the filter being operative to receive the second amplified signal and the second control signal and to generate, as an output thereof, the first control signal.

22. A system including at least one base station and a plurality of terminals adapted for communicating with the base station, at least one of the terminals in the system comprising:

at least one variable gain amplifier (VGA) operative to receive an input signal and to generate an amplified signal, a gain of the VGA being controlled as a function of at least a first control signal; and

an AGC circuit coupled to the VGA and being operative to generate the first control signal as a function of at least the amplified signal, the AGC circuit having a bandwidth that is controlled as a function of at least a second control signal such that the bandwidth is independent of the amplified signal;

wherein the AGC circuit is operative to receive the second control signal, the second control signal being indicative of a motion of the terminal.