Philips Magnetoresistive Sensor manual Technique Effect

Philips Semiconductors

Magnetoresistive sensors for

magnetic field measurement

General

The influence of other disturbing fields can also be eliminated provided they are well known, by adding a second current source to the compensating coil. Such fields might be those arising from the set-up housing, ferromagnetic components placed close to the sensor or magnetic fields from electrical motors.

The brief summary in Table 3 compares the types of compensation and their effects, so they can be assessed for their suitability in a given application. Because these options encompass a range of costs, the individual requirements of an application should be carefully analysed in terms of the performance gains versus relative costs.

		CLOCK
FLIPPING	LF	PRE-AMPLIFIER
		WITH
SOURCE		SUPRESSION
	LC	OF OFFSET

PHASE-

SENSITIVE

DEMODULATOR

CURRENT

REGULATOR

VOLTAGE & CURRENT

OUTPUT

MBH619

Fig.34 Block diagram of compensation circuit.

Table 4 Summery of compensation techniques

TECHNIQUE	EFFECT
Setting	avoids reduction in sensitivity due to constant stabilization field
Flipping	avoids reduction in sensitivity due to constant stabilization field, as well as
	compensating for sensor offset and offset drift due to temperature
Current supply	reduction of sensitivity drift with temperature by a factor of two
Electro-magnetic feedback	accurate compensation of sensitivity drift with temperature

2000 Sep 06 29