Featured Post

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

on
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
2

Series Resistance and Ohm's Law

on

So far, we have learned that if two or more resistors are connected end to end, they are in a SERIES circuit. We learned that the total resistance in a series circuit is equal to the sum of the individual resistances. What we didn't discuss, so far, was the relationship between Voltage, Current, and Resistance in a circuit with multiple resistances.

If we examine our waterflow circuit, we find that any water which flows past the 3rd valve, must first flow past the 2nd and 1st valves. By this we can deduce that the current, or flow of water, is the same past all three valves. At no time can more water flow past one valve than past another. The same is true in electronics. In a SERIES circuit, the current is the same at every point.

Using our previous example of 2 Ω resistors, if we then have a 12 Volt source, what would be our current through the circuit? Let us examine this. We know that because the circuit is series, no matter where in the circuit we are, the current will remain the same. So the problem is, what would be the given current for the complete circuits given voltage and resistance totals? Adding up our 3 resistors, we come to 6 W , and we know our Voltage is 12. So using Ohms Law, we derive this formula: