The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 08, 1997
Filed:
Oct. 05, 1994
Johannes O Voorman, Eindhoven, NL;
Joao N Ramalho, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
An arrangement for reading out an information signal from a magnetic record carrier. The arrangement includes a read head having a magneto-resistive (MR) element (R.sub.m1) with a first terminal (3) connected to a first point (13) of constant potential, and a second terminal (4); a bias-current generator (2) having an output (5) for supplying a bias-current to the MR element; and an amplifier circuit (1) having a first terminal (6) coupled to the output (5) of the bias-current generator (2), and a second terminal (7) coupled to the second terminal (4) of the magneto-resistive element (R.sub.m1) so as to form a series arrangement of the bias-current generator, the amplifier circuit and the magneto-resistive element. At an output terminal (8), the information signal is available. The amplifier circuit (1) includes a MOS transistor T.sub.1 coupled between the output terminal (8) and the second terminal (7), and a feedback circuit, including a resistor (R.sub.1) and a capacitor (C.sub.1), having a low cut-off frequency (R.sub.1,C.sub.1) which provides a bias voltage to the gate of the MOS transistor (T.sub.1) and forces the bias-current of the bias-current generator (2) to flow through the MR element. Fast settling of the arrangement is possible by short-circuiting, via a switch (S.sub.1), the resistor (R.sub.1), a high charge current for capacitor C.sub.1 being supplied by a buffer amplifier (310). The buffer amplifier (310), the resistor R.sub.1 and the switch S.sub.1 provide fast settling without generating undesired off-set.