Claims
- 1. A method for determining an operative level of a magnetoresistive element comprising steps of:
biasing the magnetoresistive element; and measuring a microwave noise signature response of the biased magnetoresistive element.
- 2. The method of claim 1, in which the microwave noise signature response of the biased magnetoresistive element is measured by steps comprising:
securing a pair of leads to the magnetoresistive element of the read/write head; attaching a test probe to the pair of leads; applying a bias current across the magnetoresistive element; and measuring a response of the magnetoresistive element to the bias current applied across the magnetoresistive element as a microwave noise signature of the magnetoresistive element.
- 3. The method of claim 1, in which the microwave noise signature response of the biased magnetoresistive element is measured by steps comprising:
securing a pair of leads to the magnetoresistive element of the read/write head; attaching a test probe to the pair of leads; applying a bias voltage across the magnetoresistive element; and measuring a response of the magnetoresistive element to the bias current applied across the magnetoresistive element as a microwave noise signature of the magnetoresistive element.
- 4. The method of claim 2, in which the bias current is supplied by a variable output bias current source.
- 5. The method of claim 3, in which the bias voltage is supplied by a variable output bias current source.
- 6. The method of claim 2, in which the test probe is a 50 Ohm airline probe comprising an air dielectric coaxial cable.
- 7. The method of claim 3, in which the test probe is a 50 Ohm airline probe comprising an air dielectric coaxial cable.
- 8. The method of claim 2, in which the bias current is supplied by a variable output bias current source, the test probe is a 50 Ohm airline probe comprising an air dielectric coaxial cable, and wherein the microwave noise signature is measured by a frequency analyzer having a frequency range of 12.2 GHz.
- 9. The method of claim 3, in which the bias current is supplied by a variable output bias current source, the test probe is a 50 Ohm airline probe comprising an air dielectric coaxial cable, and wherein the microwave noise signature is measured by a frequency analyzer having a frequency range of 12.2 GHz.
- 10. A preamplifier circuit configured for measuring a microwave noise signature of a magnetoresistive element biased by a pair of energy sources comprising:
an amplifier; and an energy source bypass switch controllingly referencing the magnetoresistive element to a ground reference.
- 11. The preamplifier circuit of claim 10, in which the pair of energy sources, is a pair of current sources.
- 12. The preamplifier circuit of claim 10, in which the pair of energy sources, is a pair of voltage sources.
- 13. The preamplifier circuit of claim 10, in which the amplifier is a differential amplifier, and wherein the preamplifier circuit further comprising:
an amplifier bypass switch disabling the differential amplifier; a test point communicating with the amplifier bypass switch providing a single ended access to the biased magnetoresistive element for measuring the microwave noise signature of the biased magnetoresistive element relative to the ground reference; and a ground test point communicating with the ground reference for referencing the microwave noise measurement of the biased magnetoresistive element.
- 14. The preamplifier circuit of claim 13, in which the differential amplifier supports a signal frequency of substantially six gigahertz, and wherein the amplifier bypass switch enables the differential amplifier.
- 15. The preamplifier circuit of claim 13, in which a first of the pair of energy sources is disabled by the energy source bypass switch and wherein a second of the pair of energy sources is a variable output energy source.
- 16. The preamplifier circuit of claim 14, in which a first of the pair of energy sources is disabled by the energy source bypass switch and wherein a second of the pair of energy sources is a variable output energy source.
- 17. The preamplifier circuit of claim 15, in which the pair of energy sources, is a pair of current sources.
- 18. The preamplifier circuit of claim 15, in which the pair of energy sources, is a pair of voltage sources.
- 19. The preamplifier circuit of claim 16, in which the pair of energy sources, is a pair of current sources.
- 20. The preamplifier circuit of claim 16, in which the pair of energy sources, is a pair of voltage sources.
- 21. A disc drive for data storage comprising:
a rotatable disc storing the data; and a read/write head with a magnetoresistive element and an inductive element, the magnetoresistive element executing a read operation to read the data from the rotatable disc, the inductive element executing a write operation to write the data to the rotatable disc, wherein the operability read/write head is determined by steps for determining an operative level of a magnetoresistive element.
RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Application No. 60/340,996 filed Oct. 30, 2001, entitled Preamp With Microwave Noise Testing Circuits.
Continuations (1)
|
Number |
Date |
Country |
Parent |
60340996 |
Oct 2001 |
US |
Child |
10175428 |
Jun 2002 |
US |