Precision temperature measurement circuit designed with OP491

The basic parameters of OP491 are: voltage drift
700Lr,V, conversion rate 0.5V/an s, bandwidth 3MHZ, working
power supply range +2.7 to +12V. The precision temperature measurement circuit designed with OP491 is shown in Figure 1-11.
    Rl, RTD and RP are bridge detection
circuits. AD589 is a 1.235V precision voltage source.
Together with Al, it forms a 200I.LA constant current source. The constant current
passes through RP and is evenly distributed to the two arms of the bridge.
When the bridge is balanced, the voltage between A and B is zero
(during debugging, use a 100.00n resistor instead of RTD and
adjust RPi so that the voltage between A and B is 0+oov
). When the temperature changes, the RTD resistance
changes and the bridge loses balance. The
output voltage VAB between A and B. A2 and A3 form an instrument amplifier
. When R = R8 and R6 = Rg, the output voltage of the amplifier
is vo = (1+R6/R7)VAB. According to the parameters in the figure, the gain of the amplifier is 274. Every time the temperature changes by
1℃, the output voltage changes by ImV.