Data storage device using windowed delta-sigma analog-to-digital converter in digital current control loop
A data storage device is disclosed comprising a voice coil motor (VCM) configured to actuate a head over a disk. The data storage device further comprises control circuitry comprising a digital current control loop including a windowed delta-sigma analog-to-digital converter (ADC) configured to control the VCM. A vibration of the data storage device is measured, and at least one of a gain or a window of the windowed delta-sigma ADC is configured based on the measured vibration.
1. A data storage device comprising:
a disk;
a head;
a voice coil motor (VCM) configured to actuate the head over the disk;
control circuitry comprising a digital current control loop including a windowed delta-sigma analog-to-digital converter (ADC) configured to control the VCM, wherein the control circuitry is configured to:
measure a vibration of the data storage device; and
configure at least one of a gain or a window of the windowed delta-sigma ADC based on the measured vibration.
2. The data storage device as recited in claim 1 , wherein the control circuitry is further configured to decrease the window of the windowed delta-sigma ADC when the measured vibration increases.
3. The data storage device as recited in claim 1 , wherein the control circuitry is further configured to increase the gain of the windowed delta-sigma ADC when the measured vibration increases.
4. The data storage device as recited in claim 1 , wherein the windowed delta-sigma ADC operates linearly when an input value is inside the window and operates non-linearly when the input value is outside the window.
5. The data storage device as recited in claim 4 , wherein:
the windowed delta-sigma ADC operates inside the window while tracking a centerline of a data track on the disk during an access operation; and
the windowed delta-sigma ADC operates outside the window while seeking the head over the disk.
6. The data storage device as recited in claim 1 , wherein the windowed delta-sigma ADC comprises:
a plurality of comparators configured to compare an input value to respective thresholds; and
a plurality of resistors configured to generate the thresholds.
7. The data storage device as recited in claim 6 , wherein the control circuitry is further configured to program the plurality of resistors in order to configure the window of the windowed delta-sigma ADC.
8. The data storage device as recited in claim 1 , wherein the windowed delta-sigma ADC comprises a plurality of registers each configured to store a multibit value corresponding to a threshold level of an input value.
9. The data storage device as recited in claim 8 , wherein the control circuitry is further configured to program the plurality of registers in order to configure the gain of the windowed delta-sigma ADC.
10. The data storage device as recited in claim 8 , wherein the control circuitry further comprises a low pass filter configured to filter the multibit values to generate a digital value representing a measured current of the VCM.
11. A windowed delta-sigma analog-to-digital converter (ADC) comprising:
a plurality of comparators configured to compare an input value to respective thresholds;
a plurality of resistors configured to generate the thresholds, wherein the resistors define a window of the windowed delta-sigma ADC;
a plurality of registers each configured to store a multibit value corresponding to one of the thresholds, wherein the multibit values define a gain of the windowed delta-sigma ADC; and
a low pass filter configured to filter the multibit values.
12. The windowed delta-sigma ADC as recited in claim 11 , wherein the plurality of resistors are programmable in order to configure the window of the windowed delta-sigma ADC.
13. The windowed delta-sigma ADC as recited in claim 11 , wherein the plurality of registers are programmable in order to configure the gain of the windowed delta-sigma ADC.
14. The windowed delta-sigma ADC as recited in claim 11 , wherein the multibit values consist of 2's complement values corresponding to positive and negative input values.
15. The windowed delta-sigma ADC as recited in claim 11 , wherein:
the windowed delta-sigma ADC operates linearly when the input value is inside the window; and
the windowed delta-sigma ADC operates non-linearly when the input value is outside the window.
16. A data storage device comprising:
a disk;
a head;
a voice coil motor (VCM) configured to actuate the head over the disk;
a digital current control loop including a windowed delta-sigma analog-to-digital converter (ADC) configured to control the VCM;
a means for measuring a vibration of the data storage device; and
a means for configuring at least one of a gain or a window of the windowed delta-sigma ADC based on the measured vibration.
17. The data storage device as recited in claim 16 , further comprising a means for increasing the window of the windowed delta-sigma ADC when the measured vibration increases.
18. The data storage device as recited in claim 16 , further comprising a means for decreasing the gain of the windowed delta-sigma ADC when the measured vibration increases.
19. The data storage device as recited in claim 16 , wherein the windowed delta-sigma ADC operates linearly when an input value is inside the window and operates non-linearly when the input value is outside the window.
20. The data storage device as recited in claim 19 , wherein:
the windowed delta-sigma ADC operates inside the window while tracking a centerline of a data track on the disk during an access operation; and
the windowed delta-sigma ADC operates outside the window while seeking the head over the disk.