Current bias voltage sense single ended preamplifier
US6404579B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 27, 2000 |
| Grant date | Jun 11, 2002 |
| Priority date | — |
| Expiry date | Oct 27, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2005/0018
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Preamplifiers are used in hard disk drive applications to read data stored on magnetic disk. Current bias current sense preamplifiers have a problem with bandwidth rolloff due to relatively high inductance. Voltage sense preamplifiers have a problem with peaking due to input capacitance. An improved current bias voltage sense preamplifier inserts a PMOS transistor M3 between the Rmr head and the bipolar transistor Q0. The PMOS transistor M3 and the bipolar transistor Q0 form a high impedance voltage sense preamplifier. Biasing of the MR head is performed transistors M6 and M7 that mirror the current supplied by the current digital to analog converter into the MR head. Hence, the preamplifier is also of the current bias type. Peaking is controlled through a programmable current in an input capacitance cancellation circuit 30.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.