4. Operational Amplifiers CIRCUITS by Ulaby & Maharbiz All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press

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Tech Brief 5: IC Fabrication All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Wafer: Thin slice of semiconductor material with highly polished surface Processed wafer is cut into many dies or chips. Lithography: Defining spatial pattern Photoresist: Polymer material that does not allow etching or deposition of areas underneath it.

Tech Brief 5: IC Fabrication All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Tech Brief 5: IC Fabrication

Tech Brief 5: IC Fabrication Lithography: Defining spatial pattern Photoresist: Polymer material that does not allow etching or deposition of areas underneath it. All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press

Tech Brief 5: IC Fabrication All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Tech Brief 5: IC Fabrication

Tech Brief 5: IC Fabrication All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press

Tech Brief 5: IC Fabrication All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Tech Brief 5: IC Fabrication

Operational Amplifier “Op Amp” All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Operational Amplifier “Op Amp” Two input terminals, positive (non- inverting) and negative (inverting) One output Power supply V+ , and Op Amp with power supply not shown (which is how we usually display op amp circuits) Op Amp showing power supply

All rights reserved. Do not copy or distribute All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Inside The Op-Amp (741)

Gain Key important aspect of op amp: high voltage gain All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Gain Key important aspect of op amp: high voltage gain Output , A is op-amp gain (or open-loop gain) – different from circuit gain G Linear response

All rights reserved. Do not copy or distribute All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Equivalent Circuit

Example 4-1: Op Amp Amplifier All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Example 4-1: Op Amp Amplifier KCL at Node a: Node a KCL at Node b: Node b For infinite A: = 5 = 4.999975

Negative Feedback Feedback: return some of the output to the input All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Negative Feedback Feedback: return some of the output to the input Negative feedback decreases input signal Achieves desired circuit gain, with wide range for input Negative Feedback No Feedback Range of Range of 5 Gain = 5 Range of : ‒2 V to +2 V : ‒10 mV to +10 mV Gain = 1million Range of

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Circuit Analysis With Ideal Op Amps All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Circuit Analysis With Ideal Op Amps Use nodal analysis as before, but with “golden rules” N Do not apply KCL at op amp output No voltage drop across op amp input No current into op amp

Noninverting Amplifier At node (max) = Vcc All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press

Inverting Amplifier All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press

Example 4-2: Input Current Source All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Example 4-2: Input Current Source Relate output voltage to input current source

Summing Amplifier All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press

Example 4-3: Solution: All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press

Difference Amplifier Note negative gain of channel 1 All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Difference Amplifier Note negative gain of channel 1

“Buffers” Sections of Circuit All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Voltage Follower “Buffers” Sections of Circuit depends on both input and load resistors is immune to input and load resistors What is the op amp doing?

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Example 4-5: Elevation Sensor All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Example 4-5: Elevation Sensor h = elevation, inversely proportional to air pressure Sensor Response Desired Output

Example 4-6: Multiple Op-Amp Circuit All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Example 4-6: Multiple Op-Amp Circuit

Measurement Uncertainty All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Measurement Uncertainty Direct Measurement v2 V0 = V2 ± 1% of V2 Thermistor G = 1 ± 1% (T = 21°C) 21°C ± 0.21°C Differential Measurement v2 G = 1 1% Thermistor V0 = (V2 ‒ V1) ± 1% of (V2 ‒ V1) (T = 21°C) 1°C ± 0.01°C v1 Much better measurement uncertainty Fixed Reference Temp = 20°C

Instrumentation Amplifier All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Instrumentation Amplifier Highly sensitive differential amplifier

Digital to Analog Converter All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Digital to Analog Converter Converts digital value into analog voltage 4-digit example

Digital to Analog Converter Represent digital value with analog voltage All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press

MOSFET (Field Effect Transistor) Active Device: Voltage Controlled Current Source Gate voltage controls drain/source current All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press

MOSFET Equivalent Circuit All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press MOSFET Equivalent Circuit Characteristic curves Idealized response

Example 4-9: MOSFET Amplifier All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Example 4-9: MOSFET Amplifier Given: Determine

Load Line You can use a “load line” to graphically determine All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Load Line You can use a “load line” to graphically determine Vout = VDS for a given Vin = VGS VDD/RD RL VDD

Digital Circuit: MOSFET Inverter All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Digital Circuit: MOSFET Inverter VDD = 15 V RL G S D ID 1 2 3 4 5 10 15 V GS =V in DS out VDD Output “High” Logic 1 Output “High” Logic 1 Output “Low” Logic 0 Output “Low” Logic 0 In Out 1 In Out Input “Low” Input “High”

Read-Only Memory (ROM) Circuits VREAD = 1 VBIT = 0100 All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press

Another Digital Circuit Element: NAND All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Another Digital Circuit Element: NAND No current flows through resistor, unless both A and B inputs turn their transistors on to “pull down” Vout VDD A B Out A B Out 1 Vout A B NAND gates can be used to build any binary logic function

Another Digital Circuit Element: NOR All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press Another Digital Circuit Element: NOR Current will flow if either A or B inputs turn their transistors on to “pull down” Vout VDD A B Out A B Out 1 Vout A B NOR gates can be used to build any binary logic function

Example: Multisim Instruments All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press

Multisim Table All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press

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Multisim: MOSFET I-V Analyzer All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press

Tech Brief 6: Display Technologies All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press

Tech Brief 6: Display Technologies Digital Light Processing (DLP) All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press

Summary All rights reserved. Do not copy or distribute. © 2013 National Technology and Science Press