Magnetoresistive speed sensor processing circuit utilizing a symmetrical hysteresis signal

US5231351A · kind A · utility

Assignee

• U.S. Philips Corporation · US

Inventors

• Jurgen Kordts · Wedel, DE
• Georg Kisters · Hamburg, DE
• Michael Ramm · Garbsen, DE

Key dates

• Filing date: Sep 18, 1991
• Grant date: Jul 27, 1993
• Expiry date: Sep 18, 2011

Classification

• Technology area (CPC G): Physics
• CPC primary: G01P3/487
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A processing circuit for a magnetoresistive rotary speed sensor (13) or the like having a comparator (11) with switching hysteresis for converting an analog sensor signal into a digital switching signal. An apparatus is provided at the input side of the comparator in order to alternately supply each of the comparator inputs, as a function of the switching signal at the output side of the comparator, symmetrically with a given hysteresis signal as a switching threshold. This apparatus also includes a preamplifier (15) which precedes the comparator non-inverting input and which amplifies the sensor signal, and an offset amplifier (18) of the same construction which precedes the comparator inverting input and which amplifiers an offset signal of a preceding offset network (21). The processing circuit provides a simple, integrable circuit which suppresses offsets and compensates for temperature and supply voltage fluctuations and any spread in tolerances of the circuit components.