Philips Magnetoresistive Sensor manual Given by, A1 = 1 +, Magnetoresistive sensor, Calculated by

Philips Semiconductors

Magnetoresistive sensors for

magnetic field measurement

General

					VS
		OP1	R10
			RT	R12
			KTY82-110	R14
	R1		R5
		RA		OP3	VO
		R4	R6
	offset			R13
	R3	R B	R7
		OP2	R9
				R11
KMZ10B	R2
					MLC145

Fig.16 KMZ10B application circuit with instrumentation amplifier.

The amplification of the input stage (‘OP1’ and ‘OP2’) is

RT

× TCKTY

(11)

given by:

TCA = ----------------------------------

RA + RB + RT

RT + RB

(9)

For the given negative ‘TC’ of the magnetoresistive sensor

A1 = 1 + --------------------

RA

and the required amplification of the input stage ‘A1’, the

where RT is the temperature dependent resistance of the

resistance ‘RA’ and ‘RB’ can be calculated by:

⎛ TCKTY

1 ⎞

KTY82 sensor and RB is the bridge resistance of the

R

= R

×

⎛

1

⎞

(12)

----------------- ×

–-------

–1

magnetoresistive sensor.

B

T

⎝ TCA

⎝

A1⎠

⎠

The amplification of the complete amplifier can be

RA

RT

+ RB

(13)

calculated by:

= --------------------

R14

A1 –1

(10)

A = A1 × ---------

where TCKTY is the temperature coefficient of the KTY

R10

sensor and TCA is the temperature coefficient of the

The positive temperature coefficient (TC) of the

amplifier. This circuit also provides for adjustment of gain

amplification is:

and offset voltage of the magnetic-field sensor.

2000 Sep 06 14