Characterizing a sensing circuit of a data storage device
View Patent ↗A data storage device is disclosed comprising a disk, a head for accessing the disk, and a sensor for generating an alternating sensor signal. The sensor is disconnected from an input of a sensing circuit and while the sensor is disconnected an alternating calibration signal is injected into the input of the sensing circuit, wherein the alternating calibration signal comprises a predetermined offset and amplitude. A response of the sensing circuit to the alternating calibration signal is evaluated to detect at least one of an offset and a gain of the sensing circuit.
1. Control circuitry configured to measure at least one of an offset and gain of a sensing circuit for use in a data storage device, the control circuitry configured to:
inject an alternating calibration signal into an input of the sensing circuit, wherein the alternating calibration signal comprises a predetermined offset and amplitude;
initialize a threshold to an initial setting;
first count a number of times the alternating calibration signal exceeds the initial threshold;
adjust the threshold;
second count a number of times the alternating calibration signal exceeds the adjusted threshold; and
detect at least one of the offset and gain of the sensing circuit based at least on the second count.
2. The control circuitry as recited in claim 1 , wherein the control circuitry is further configured to adjust a parameter of the sensing circuit based on at least one of the detected offset and the detected gain of the sensing circuit.
3. The control circuitry as recited in claim 2 , wherein:
the sensing circuit comprises a comparator for comparing an alternating sensor signal to a threshold; and
the parameter comprises the threshold.
4. The control circuitry as recited in claim 2 , wherein:
the sensing circuit comprises an adder for adding an offset to an alternating sensor signal; and
the parameter comprises the added offset.
5. The control circuitry as recited in claim 2 , wherein:
the sensing circuit comprises an amplifier for amplifying an alternating sensor signal; and
the parameter comprises a gain of the amplifier.
6. The control circuitry as recited in claim 1 , wherein the control circuitry is further configured to adjust the threshold until the second count is at least one.
7. The control circuitry as recited in claim 1 , wherein the control circuitry is further configured to adjust the threshold until the second count rises above a predetermined level.
8. The control circuitry as recited in claim 1 , wherein the control circuitry is further configured to adjust the threshold until the second count falls below a predetermined level.
9. The control circuitry as recited in claim 1 , wherein the control circuitry is further configured to:
adjust an amplitude of the alternating calibration signal; and
evaluate a response of the sensing circuit to the adjusted alternating calibration signal.
10. The control circuitry as recited in claim 9 , wherein the control circuitry is further configured to adjust a non-linear component of the sensing circuit based on the response of the sensing circuit to the adjusted alternating calibration signal.
11. The control circuitry as recited in claim 10 , wherein the non-linear component of the sensing circuit comprises a digital-to-analog converter.
12. A test station comprising control circuitry configured to measure at least one of an offset and gain of a sensing circuit for use in a data storage device, the control circuitry configured to:
inject an alternating calibration signal into an input of the sensing circuit, wherein the alternating calibration signal comprises a predetermined offset and amplitude;
initialize a threshold to an initial setting;
first count a number of times the alternating calibration signal exceeds the initial threshold;
adjust the threshold;
second count a number of times the alternating calibration signal exceeds the adjusted threshold; and
detect at least one of the offset and gain of the sensing circuit based at least on the second count.
13. A method of measuring at least one of an offset and gain of a sensing circuit for use in a data storage device, the method comprising:
injecting an alternating calibration signal into an input of the sensing circuit, wherein the alternating calibration signal comprises a predetermined offset and amplitude;
initializing a threshold to an initial setting;
first counting a number of times the alternating calibration signal exceeds the initial threshold;
adjusting the threshold;
second counting a number of times the alternating calibration signal exceeds the adjusted threshold; and
detecting at least one of the offset and gain of the sensing circuit based at least on the second count.