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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 Switching Power Supply Circuit Diagram

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Build a Switching Power Supply Circuit Diagram. This is a Switching Power Supply Circuit Diagram. This low-voltage high-current output, switching de power supply is running off the 220-Vac input. In this circuit, an ST2 diac relaxation oscillator, Q3, Cl, and the diac, initiates conduction of the output switching transistor Ql, the on-time of which is maintained constant by a separate tiring computation network consisting of Q2, C2, SUS, and SCR 1. 

The output voltage, consequently, is dependent on the duty cycle. To compensate for unwanted variations of output voltage because of input voltage or load resistance fluctuations, an HllC wired as a linear-model unilateral PNP transistor in a stable differential amplifier configuration is connected into the galvanic ally isolated negative-feedback loop. 


Switching Power Supply Circuit Diagram

The loop determines the duty cycle and hence the output voltage. Of further interest in this circuit is the use of several low-current, high-voltage, 400V VvRM thyristors (Q2, Q3,) which are also used as pnp remote-base transistors. Short-circuit protection is assured by coupling Ql collector-current feedback into the tum-off circuitry via Rss·

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