Use of shunt resistor with large RA product tunnel barriers
View Patent ↗A read head for use with an interconnect transmission line having a characteristic impedance of Z 0 includes a tunnel valve device and a shunt resistor RS that is connected in parallel across the tunnel valve device. The tunnel valve device has a device resistance R T corresponding to a predetermined resistance-area (RA) product. The value of the shunt resistance is based on the parallel combination of R T and R S substantially equaling the characteristic impedance Z 0 of the interconnect transmission line. The predetermined resistance-area (RA) product is about equal to at least about 10 Ohms-μm 2 . Alternatively, the predetermined resistance-area (RA) product is about equal to a “corner” value of RA c for the tunnel valve device.
1. A read head for use with an interconnect transmission line having a characteristic impedance of Z 0 , the read head comprising:
a tunnel valve device, the tunnel valve device having a device resistance R T corresponding to a predetermined resistance-area (RA) product; and
a shunt resistance R S connected in parallel across the tunnel valve device, a value of the shunt resistance being based on the parallel combination of R T and R S substantially equaling a predetermined selected value of resistance, wherein the shunt resistance R S is located on a substrate/slider for the read head.
2. The read head according to claim 1 , wherein the predetermined selected value of resistance substantially equaling the characteristic impedance Z 0 of the interconnect transmission line.
3. The read head according to claim 1 , wherein the predetermined resistance-area (RA) product is about equal to at least about 10 Ohms-μm 2 .
4. The read head according to claim 1 , wherein the predetermined resistance-area (RA) product is about equal to a value of a resistance-area (RA) product in which a Tunnel Magneto-Resistance (TMR) ratio ΔR/R 0 for the tunnel valve device does not substantially increase for further increase in the value of the resistance-area (RA) product.
5. A disk drive, comprising:
an interconnect transmission line having a characteristic impedance of Z 0 ; and
a read head having a tunnel valve device and a shunt resistance R S , the tunnel valve device having a device resistance R T corresponding to a predetermined resistance-area (RA) product; the shunt resistance R S being connected in parallel across the tunnel valve device, and a value of the shunt resistance being based on the parallel combination of R T and R S substantially equaling a predetermined selected value of resistance, wherein the shunt resistance R S is located on a substrate/slider for the read head.
6. The disk drive according to claim 5 , wherein the predetermined selected value of resistance substantially equaling the characteristic impedance Z 0 of the interconnect transmission line.
7. The disk drive according to claim 5 , wherein the predetermined resistance-area (RA) product is about equal to at least about 10 Ohms-μm 2 .
8. The disk drive according to claim 5 , wherein the predetermined resistance-area (RA) product is about equal to a value of a resistance-area (RA) product in which a Tunnel Magneto-Resistance (TMR) ratio ΔR/R 0 for the tunnel valve device does not substantially increase for further increase in the value of the resistance-area (RA) product.
9. A read head for use with an interconnect transmission line having a characteristic impedance of Z 0 , the read head comprising:
a tunnel valve device, the tunnel valve device having a device resistance R T corresponding to a predetermined resistance-area (RA) product; and
a shunt resistance R S connected in parallel across the tunnel valve device, a value of the shunt resistance being based on the parallel combination of R T and R S substantially equaling a predetermined selected value of resistance, wherein the shunt resistance R S is located at an arm electronics module associated with the read head.
10. The read head according to claim 9 , wherein the predetermined selected value of resistance substantially equaling the characteristic impedance Z 0 of the interconnect transmission line.
11. The read head according to claim 9 , wherein the predetermined resistance-area (RA) product is about equal to at least about 10 Ohms-μm 2 .
12. The read head according to claim 9 , wherein the predetermined resistance-area (RA) product is about equal to a value of a resistance-area (RA) product in which a Tunnel Magneto-Resistance (TMR) ratio ΔR/R 0 for the tunnel valve device does not substantially increase for further increase in the value of the resistance-area (RA) product.
13. A disk drive, comprising:
an interconnect transmission line having a characteristic impedance of Z 0 ; and
a read head having a tunnel valve device and a shunt resistance R S , the tunnel valve device having a device resistance R T corresponding to a predetermined resistance-area (RA) product; the shunt resistance R S being connected in parallel across the tunnel valve device, and a value of the shunt resistance being based on the parallel combination of R T and R S substantially equaling a predetermined selected value of resistance, wherein the shunt resistance R S is located at an arm electronics module associated with the read head.
14. The disk drive according to claim 13 , wherein the predetermined selected value of resistance substantially equaling the characteristic impedance Z 0 of the interconnect transmission line.
15. The disk drive according to claim 13 , wherein the predetermined resistance-area (RA) product is about equal to at least about 10 Ohms-μm 2 .
16. The disk drive according to claim 13 , wherein the predetermined resistance-area (RA) product is about equal to a value of a resistance-area (RA) product in which a Tunnel Magneto-Resistance (TMR) ratio ΔR/R 0 for the tunnel valve device does not substantially increase for further increase in the value of the resistance-area (RA) product.