Objectives Analyze series-parallel circuits Analyze loaded voltage dividers Analyze ladder networks Analyze a Wheatstone bridge
Basic Idea Given a circuit; steps to analyze a circuit: Find the total resistance Determine all parallel resistors and series resistors Simplify the given circuit Use KCL and Ohm’s law to find all currents Use Ohm’s law to find all voltages
Find the total resistance R1 + R2 || R3 + R4 || R5
Loaded Voltage Dividers When a load resistor R L is connected from the output to ground, the output voltage is reduced by an amount that depends on the value of R L.
Loading Effect of a Voltmeter Multimeter What happens if RL >> R2? So, what is the internal resistance of a DMM?
Analysis of a Ladder Network A resistive ladder network is a special type of series- parallel circuit. One form of ladder network is commonly used to scale down voltages to certain weighted values for digital- to-analog conversion Called R/2R Ladder Network To find total resistance of a ladder network, start at the point farthest from the source and reduce the resistance in steps.
The R/R2 Ladder Network Only Input 4 is HIGH Only Input 3 is HIGH Used for Digital-to-analog converter!
Examining Digital-to-Analog Conversion For Extra credit: Change the circuit to generate this output: