Patent ID: 8482872

Claim:
A hard-disk drive, comprising: a head slider comprising a read element and a write element disposed on an air bearing surface; a magnetic-recording disk rotatably mounted on a spindle; a voice coil motor configured to move the head slider to access portions of said magnetic-recording disk; and a read/write integrated circuit (IC) configured to condition write signals sent to the write element and amplify read signals from the read element, wherein the head slider comprises (a) a first resistive temperature detector (RTD) that is located relatively near the air bearing surface and (b) a second RTD that is offset from the air bearing surface, wherein the read/write IC is configured to detect when the head slider makes physical contact with the magnetic-recording disk based on a difference in temperature measured by the first RTD and the second RTD, and wherein the first RTD and the second RTD comprised within the head slider form a bridge circuit with a first IC resistor and a second IC resistor comprised within the read/write IC, and wherein a common mode voltage of the bridge circuit is used to measure the temperature of the head slider while a differential mode voltage of the bridge circuit is used to measure a low-frequency signal from a first path of the bridge circuit to detect physical contact between the head slider and the disk and to measure a high-frequency signal from a second path of the bridge circuit to measure disk topography features.