Channel state aided automatic gain control

• US 20070296500A1
• Filed: 06/09/2006
• Published: 12/27/2007
• Est. Priority Date: 06/09/2006
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Yang, Xueshi
• Granted Patent: US 7,501,895 B2
• Time in Patent Office: Days
• US Class Current: 330/278
• CPC Class Codes: H03G 3/3052 in bandpass amplifiers (H.F. or I.F.) or in frequency-changers used in a (super)heterodyne receiver H03G3/32, H03G3/34 take precedence

Abstract

An apparatus comprises a circuit for producing a channel gain control signal, and an amplifier for amplifying a signal of interest in response to the channel gain control signal, wherein the channel gain control signal is generated from a channel state signal that is not derived from the signal of interest.

Claims

1. An apparatus comprising:

a circuit for producing a channel gain control signal;

an amplifier for amplifying a signal of interest in response to the channel gain control signal; and

wherein the channel gain control signal is generated from a channel state signal that is not derived from the signal of interest.

2. The apparatus of claim 1, wherein the circuit for producing the channel gain control signal comprises:

a sensor for measuring a channel property that affects the amplitude of the signal of interest; and

a processor for converting the measured channel property to the channel gain control signal.

3. The apparatus of claim 1, wherein the circuit for producing the channel gain signal comprises:

a sensor for producing a head/media position signal; and

a processor for producing a relative speed signal in response to the head/media position signal, wherein the head/media position signal is used to produce the channel gain signal.

4. The apparatus of claim 1, further comprising:

a second-stage variable gain amplifier for amplifying the signal of interest in response to a loop gain control signal.

5. An apparatus comprising:

a first circuit for producing a loop gain signal;

a second circuit for producing a channel gain signal; and

an amplifier for amplifying a signal of interest in response to a gain control signal;

wherein the gain control signal comprises a combination of the loop gain signal and the channel gain signal.

6. The apparatus of claim 5, wherein the amplifier produces a gain-controlled signal, and the first circuit for producing a loop gain signal comprises:

a detector for producing an estimated ideal signal;

a component for combining the gain-controlled signal and the estimated ideal signal to produce an error signal; and

a third circuit for processing the error signal to produce the loop gain signal.

7. The apparatus of claim 6, wherein the component for combining the gain-controlled signal and the estimated ideal signal to produce an error signal comprises a summation point.

8. The apparatus of claim 6, wherein the third circuit comprises a second amplifier for multiplying the error signal by the signal of interest to produce an intermediate variable signal, and a third amplifier for multiplying the intermediate variable signal by an adaptation constant.

9. The apparatus of claim 5, wherein the amplifier produces a gain-controlled signal, and the first circuit for producing a loop gain signal comprises:

a processor for determining the average signal power of the gain-controlled signal;

a component for combining the average signal power and a desired signal power to produce an error signal; and

a third circuit for processing the error signal to produce the loop gain signal.

10. The apparatus of claim 8, wherein the component for combining the average signal power and a desired signal power to produce an error signal comprises a summation point.

11. The apparatus of claim 8, wherein the third circuit comprises a second amplifier for multiplying the error signal by the signal of interest to produce an intermediate variable signal, and a third amplifier for multiplying the intermediate variable signal by an adaptation constant.

14. The method of claim 10, wherein the step of producing the channel gain signal comprises:

producing a head/media position signal; and

producing a relative speed signal in response to the head/media position signal, wherein the head/media position signal is used to produce the channel gain signal.

12. A method comprising:

producing a channel gain control signal; and

amplifying a signal of interest in response to the channel gain control signal;

wherein the channel gain control signal is generated from a channel state signal that is not derived from the signal of interest.

13. The method of claim 12, wherein the step of producing a channel gain control signal comprises:

measuring a channel property that affects the amplitude of the signal of interest; and

converting the measured channel property to the channel gain control signal.

15. The method of claim 12, further comprising:

amplifying the signal of interest in response to a loop gain control signal using a second-stage amplifier.

16. A method comprising:

producing a loop gain signal;

producing a channel gain signal; and

amplifying a signal of interest in response to a gain control signal;

wherein the gain control signal comprises a combination of the loop gain signal and the channel gain signal.

17. The method of claim 16, wherein the step of producing a channel gain signal comprises:

producing a head/media position signal; and

producing a relative speed signal in response to the head/media position signal.

18. The method of claim 16, further comprising:

producing a gain-controlled signal;

producing an estimated ideal signal;

combining the gain-controlled signal and the estimated ideal signal to produce an error signal; and

processing the error signal to produce the loop gain signal.

19. The method of claim 16, further comprising:

producing a gain-controlled signal;

determining the average signal power of the gain-controlled signal;

combining the average signal power and a desired signal power to produce an error signal; and

processing the error signal to produce the loop gain signal.

20. An apparatus comprising:

a ferroelectric storage medium;

an array of probes for reading data from the ferroelectric storage medium;

a first circuit for producing a loop gain signal;

a second circuit for producing a channel gain signal; and

an amplifier for amplifying a read signal from the probes in response to a gain control signal;

wherein the gain control signal comprises a combination of the loop gain signal and the channel gain signal.