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

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

Build a High voltage Bucking Regulator Circuit Diagram

This High voltage Bucking Regulator Circuit Diagram is basically tbe classic bucking regulator, except it uses a TMOS N-channel power FET for the chopper and creates its own supply for the gate control. Tht unique aspect of this circuit is how it generates a separate supply for the gate circuit, which must be greater than Vvv. 

When power is applied, C2 charges, through D2, to +12 V. At this time, Q1 is off and the voltage at point A is just below zero. When the pulse-modulated signal is applied, the optoisolator transistors, Q2 and Q3, supply a signal to Q1 that turns it on. The voltage at point A then goes to Vvn. C2 back-biases D2, and the voltage at point B becomes 12 V above VnnĂ‚· After Q1 is turned on, current starts to flow through L1 into C1, increasing until Q1 turns off. 


High voltage Bucking Regulator Circuit Diagram

The current still wants to flow through Ll, so the voltage at point A moves toward negative infinity, but is clamped by D1 to just below zero. Current flows less and less into C1, until Q1 turns on again. Q2 and Q3 drive Q1 `s gate between the voltages at point A and B, which is always a12 V swing, so Vcs max. is never exceeded. For proper operation, the 12-V supply has to be established before the pulse-width modulator signal is applied.

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