Device for limiting current in a sensor

• US 20020176187A1
• Filed: 04/23/2001
• Published: 11/28/2002
• Est. Priority Date: 04/23/2001
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Bishop, Andrew
• Granted Patent: US 7,292,400 B2
• Time in Patent Office: Days
• US Class Current: 360/46
• CPC Class Codes: G11B 2005/0016 of magnetoresistive transducers
• CPC Class Codes: G11B 5/02 Recording, reproducing, or erasing methods; Read, write or erase circuits therefor
• CPC Class Codes: G11B 5/40 Protective measures on heads, e.g. against excessive temperature G11B5/31 takes precedence; protection against wear G11B5/255 ; protective structure of the head: see under structures, e.g. G11B5/3106

Abstract

A read/write device for a disk drive is disclosed. The read/write device includes a pre-amplifier and a recording head. The read/write device also includes a write signal path between the pre-amplifier and the recording head. The write signal path includes a write current. The read/write device also includes a read signal path between the pre-amplifier and the recording head. The read signal path includes an induced current related to the write current. The read/write device also includes a shunt path in the pre-amplifier to draw a part of the induced current from the read signal path.

Claims

1. A read/write device for a disk drive, having a pre-amplifier and a recording head, comprising:

a write signal path between said pre-amplifier and said recording head, said write signal path having a write current;

a read signal path between said pre-amplifier and said recording head, said read signal path having an induced current related to said write current; and

a shunt path in said pre-amplifier to draw a part of said induced current from said read signal path.

2. The read/write device of claim 1, further comprising a sensor in said recording head coupled to said read signal path.

3. The read/write device of claim 2, wherein said induced current generates a sensor current of about 0.25 milliamps.

4. The read/write device of claim 1, further comprising a read amplifier in said pre-amplifier.

5. The read/write device of claim 3, wherein said shunt path is coupled between said read signal path and said read amplifier.

6. The read/write device of claim 1, wherein said shunt path includes a set of transmission gates.

7. The read/write device of claim 6, wherein said set of transmission gates includes a first transistor and a second transistor.

8. The read/write device of claim 7, wherein said first transistor is an n-channel transistor.

9. The read/write device of claim 7, wherein said second transistor is a p-channel transistor.

10. The read/write device of claim 6, wherein said set of transistors has a low drain-to-source channel resistance.

11. The read/write device of claim 1, wherein said shunt path has a resistance of about 10 ohms.

12. The read/write device of claim 1, wherein said pre-amplifier includes a write driver to generate said write current in said write signal path.

13. The read/write device of claim 10, wherein said write driver generates an electric field.

14. The read/write device of claim 10, wherein said write current generates a magnetic field.

16. The read/write device of claim 15, further comprising a sensor coupled to said read signal path.

17. The read/write device of claim 15, wherein said shunt path comprises two transmission gates.

18. The read/write device of claim 15, wherein said shunt path has a resistance below about 10 ohms.

19. The read/write device of claim 15, wherein said shunt path couples said read signal path to a read amplifier.

15. A read/write device, comprising:

a write signal path having a write current, said write current to induce an induced current in a read signal path; and

a shunt path to shunt said induced current from said read signal path.

20. A method for limiting a sensor current in a magneto-resistive sensor, comprising:

inducing a current in a read signal path coupled to said sensor; and

shunting said current from said read signal path with a shunt path, wherein said shunt path is opposite said sensor on said read signal path; and

inducing a voltage in a read signal path coupled to said sensor; and

shunting the current that is generated due to said voltage from said read signal path, wherein said shunt path is opposite said sensor on said read signal path.

21. The method of claim 20, further comprising generating a write current in a write signal path.

22. The method of claim 21, further comprising generating an electric field about said write signal path, said electric field inducing said current.

23. The method of claim 21, further comprising generating a magnetic field about said write signal path, said magnetic field inducing a voltage potential

24. The method of claim 20, further comprising transmission gates within said shunt path.

25. The method of claim 20, further comprising saturating transistors within said transmission gates.