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High CMRR Instrumentation Amplifier (Schematic and Layout) design for biomedical applications

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Instrumentation amplifiers are intended to be used whenever acquisition of a useful signal is difficult. IA’s must have extremely high input impedances because source impedances may be high and/or unbalanced. bias and offset currents are low and relatively stable so that the source impedance need not be constant. Balanced differential inputs are provided so that the signal source may be referenced to any reasonable level independent of the IA output load reference. Common mode rejection, a measure of input balance, is very high so that noise pickup and ground drops, characteristic of remote sensor applications, are minimized.Care is taken to provide high, well characterized stability of critical parameters under varying conditions, such as changing temperatures and supply voltages. Finally, all components that are critical to the performance of the IA are internal to the device. The precision of an IA is provided at the expense of flexibility. By committing to the one specific task of
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Automatic room fan controller using OpAmp:

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This is the another application of a comparator. This can save the power and we don't need to switch ON and OFF the ceiling FAN manually. here we can set the threshold voltage to our desired value. The ceiling fan will be switched ON when the temperature increases the threshold value. We are using LM35 sensor to sense the room temperature. The sensitivity of this LM35 sensor is 10mv/ 'C. I want that fan to be switched on when the temperature increases more than 27'C. so set my threshold voltage to
                                 Vthreshold = 27'C x 10mv = 270mv = 0.27V

                      here the room temperature is 26'c so the output voltage is < 0.27V ; Fan off
  to see the output 



 when the temperature increases to 27'c or more, the output voltage of LM35 will increases to more than 0.27V. so that opamp output will goes to +Vsat=+5v. This will switch ON the transistor and so relay connects. This will switch ON the ceiling fan.

    here the temperature is 28'c so the output voltage >0.27v; fan ON      LM35 sensor

Location: Southern Asia

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