Auto-ranging attenuators for read channels
AssigneeAgere Systems Inc.
InventorViswanath Annampedu
Life of this patent
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Abstract
A recording system, such as a magnetic or optical recording system, sets input attenuation level setting and variable gain amplifier (VGA) operating region during zero gain start (ZGS) by sharing the ZGS adjustment between attenuator settings and VGS gain setting. Further adjustment is made to attenuator settings and VGS gain setting for each subsequent servo or read sector event. The input attenuation level setting and variable gain amplifier (VGA) operating region are set so as to minimize effects of gain error due to incorrect attenuator setting, and subsequently operate the VGA near the center of its range where the non-linear effects are minimal.
Claims33
A method of dynamically adjusting a level of a readback signal, the method comprising the steps of:
- (a) detecting an event in the readback signal;
- (b) generating a zero gain start (ZGS) adjustment value for the event;
- (c) dividing the ZGS adjustment value into an attenuator portion and a gain portion;
- and (d) adjusting:
- i) an attenuation, by at least one attenuator, of the readback signal based on the attenuator portion, and
- ii) a gain, by a variable gain amplifier (VGA), of the readback signal toward to within a predefmed sub-range based on the gain portion,
- wherein the at least one attenuator and the VGA are adapted to be selectively activated at the same time.
An apparatus for dynamically adjusting a level of a readback signal, the apparatus comprising:
- a zero gain start (ZGS) circuit adapted to generate a ZGS adjustment value for an event in a readback signal;
- a processor adapted to 1) divide the ZGS adjustment value into an attenuator portion and a gain portion;
- and 2) adjust:
- i) an attenuation, by at least one attenuator, of the readback signal based on the attenuator portion, and
- ii) a gain, by a variable gain amplifier (VGA), of the readback signal toward to within a predefmed sub-range based on the gain portions
- wherein the at least one attenuator and the VGA are adapted to be selectively activated at the same time.
A computer-readable medium having stored thereon a plurality of instructions, the plurality of instructions including instructions which, when executed by a processor, cause the processor to implement a method for dynamically adjusting a level of a readback signal, the method comprising the steps of:
- (a) detecting an event in the readback signal;
- (b) generating a zero gain start (ZGS) adjustment value for the event;
- (c) dividing the ZGS adjustment value into an attenuator portion and a gain portion;
- and
- (d) adjusting:
- i) an attenuation, by at least one attenuator, of the readback signal based on the attenuator portion, and
- ii) a gain, by a variable gain amplifier (VGA), of the readback signal toward to within a predefmed sub-range based on the gain portion,.
- wherein the at least one attenuator and the VGA are adapted to be selectively activated at the same time.
A method of dynamically adjusting a level of a readback signal, the method comprising the steps of:
- (a) detecting an event in the readback signal;
- (b) generating a zero gain start (ZGS) adjustment value for the event;
- (c) dividing the ZGS adjustment value into an attenuator portion and a gain portion;
- and
- (d) adjusting:
- i) an attenuation, by at least one attenuator, of the readback signal based on the attenuator portion, and
- ii) a gain, by a variable gain amplifier (VGA), of the readback signal toward to within a predefmed sub-range based on the gain portion,
- wherein:
- step (c) comprises the step of dividing the attenuator portion into two or more attenuator stage portions corresponding to each attenuator stage;
- for step (d), the attenuator comprises at least two attenuator stages, at least one attenuator stage is a slow settling attenuator, and at least one other attenuator stage is a fast settling attenuator.
A method of dynamically adjusting a level of a readback signal, the method comprising the steps of:
- (a) detecting an event in the readback signal;
- (b) generating a zero gain start (ZGS) adjustment value for the event;
- (c) dividing the ZGS adjustment value into an attenuator portion and a gain portion;
- and
- (d) adjusting:
- i) an attenuation, by at least one attenuator, of the readback signal based on the attenuator portion, and
- ii) again, by a variable gain amplifier (VGA), of the readback signal toward to within a predefmed sub-range based on the gain portion,
- wherein step (b) comprises the steps of (1) detecting a preamble in the readback data, and (2) generating the ZGS adjustment value during an acquire mode.
An apparatus for dynamically adjusting a level of a readback signal, the apparatus comprising:
- a zero gain start (ZGS) circuit adapted to generate a ZGS adjustment value for an event in a readback signal;
- a processor adapted to 1) divide the ZGS adjustment value into an attenuator portion and a gain portion, and 2) adjust:
- i) an attenuation, by at least one attenuator, of the readback signal based on the attenuator portion, and
- ii) a gain, by a variable gain amplifier (VGA), of the readback signal toward to within a predefmed sub-range based on the gain portion,
- wherein:
- the attenuator comprises at least two attenuator stages;
- the attenuator portion is divided into two or more attenuator stage portions corresponding to each attenuator stage;
- at least one attenuator stage is a slow settling attenuator;
- and at least one other attenuator stage is a fast settling attenuator.
An apparatus for dynamically adjusting a level of a readback signal, the apparatus comprising:
- a zero gain start (ZGS) circuit adapted to generate a ZGS adjustment value for an event in a readback signal;
- a processor adapted to 1) divide the ZGS adjustment value into an attenuator portion and a gain portion;
- and 2) adjust:
- i) an attenuation, by at least one attenuator, of the readback signal based on the attenuator portion, and
- ii) a gain, by a variable gain amplifier (VGA), of the readback signal toward to within a predefmed sub-range based on the gain portion,
- wherein the ZGS circuit detects a preamble in the readback data and generates the ZGS adjustment value during an acquire mode.
Dependencies are inferred from the claim text.