Signal Amplification

Thevenin equivalent, Impedence matching, Operational Amplifiers (summing , multiplying, differentiation, difference & integration)

impedence matching

when combining two distinct circuits, one of them draws voltage from the other because of different effective resistance (create a load)

→ to minimize the problem we match the impedence of the two circuits (=/ equal)

best way to get EQUIVALENT RESISTANCE is to get THEVENIN EQUIVALENT

Thevenin equivalent

turns a complicated circuit into a simpler one → Multiple sources and resistors will be converted into a single voltage source and series resistor

from viewpoint of the load circuits are perfectly equivalent

Thevenin equivalent - how to

Steps:

1. Review your circuit, identify your load and the nodes it is connected to.

2. Remove the load resistor.

3. Find R_Th by shorting all voltage sources and by open circuiting all the current sources and then see what the resistance looks like from the point of view of the nodes where the load resistor was located.

4. Find V_Th by finding the voltage across the nodes the load was originally hooked to, using standard circuit analysis methods.

5. Replace the load and find the current flowing through the load with these new values.

6. Sanity check!

what is the thévenin voltage and resistance for a voltage divider

-thévenin resistance is found by removing voltage supply from circuit and considering resistance across two output terminals (start at A and redraw the circuit whilst taking into consideration what happens when we reah each node)

-for voltage divider → thévenin resistance (see picture)

thévenin voltage for wheatstone bridge

Thévenin resistance for wheatstone bridge

obtained by shortening the circuit (ignoring the voltage source)