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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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Build a Amplifier Attenuator Circuit Diagram

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Build a Amplifier Attenuator Circuit Diagram. A op amp and transistors Q1 and Q2 exponential converter to generate an exponential gain control current, which is introduced into the rectifier. A reference current of 150 pA, (15 V and RZO = lOO-k), is attenuated by a factor of two (6 dB) for each increase of tension in the control voltage. Capacitor C6 slows secure changes to a period of 20 IDS constant (C6 x IR) such that a sudden change in the control voltage will produce a gain change smooth sound. RI8 ensures that for control voltages of the circuit will go to great attenuation full. 

The rectifier bias current which would normally limit the gain reduction around 70 dB. RI6 attracts more courses of the rectifier. After about 50 dB of attenuation to -6 dB / V slope, with the increase in slope and the attenuation becomes much faster than the circuit to close completely at about 9 V control voltage. Al should be a low noise, high intensity, scanning speed, op. R13 and R14 in place around 0 V bias to the output.


Amplifier Attenuator Circuit Diagram

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