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handbook of modern sensors

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198 5 Interface Electronic Circuits<br />

(A)<br />

(B)<br />

(C)<br />

(D)<br />

Fig. 5.40. Temperature compensation <strong>of</strong> a bridge circuit: (A) with NTC thermistor; (B) with a<br />

fixed resistor; (C) with a temperature-controlled voltage source; (D) with a current source.<br />

Option 2: The compensation network is a fixed resistor. This is the most popular<br />

temperature compensation <strong>of</strong> a resistive Wheatstone bridge. A fixed resistor (Fig.<br />

5.40B) R t = R c must have low-temperature sensitivity (50 ppm or less). It can be<br />

stated that<br />

1 ∂R c<br />

= 0,<br />

R c ∂T<br />

(5.58)<br />

and Eq. (5.57) is simplified to<br />

−β = ∂R<br />

∂T<br />

( 1<br />

R − 1<br />

R + R c<br />

)<br />

. (5.59)

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