Basic Analog Electronic Circuits Dr. Lynn Fuller

Transcription

1 ROCHESTER INSTITUTE OF TECHNOLOGY MICROELECTRONIC ENGINEERING Dr. Lynn Fuller Webpage: 82 Lomb Memorial Drive Rochester, NY Tel (585) MicroE webpage: Basic_Analog_Circuits.ppt Page 1

2 OUTLINE Introduction Op Amp Comparator Bistable Multivibrator RC Oscillator RC Integrator Peak Detector Switched Capacitor Amplifier Capacitors Design Examples References Homework Page 2

3 INTRODUCTION Analog electronic circuits are different from digital circuits in that the signals are expected to have any value rather than two discrete values. Primitive analog components include the diode, mosfet, BJT, resistor, capacitor, etc,. Analog circuit building blocks include single stage amplifiers, differential amplifiers, constant current sources, voltage references, etc. Basic analog electronic ciruits include the operational amplifier, inverting amplifier, noninverting amplifier, integrator, bistable multivibrator, peak detector, comparator, RC oscillator, etc. Mixedmode analog integrated circuits include DtoA, AtoD, etc. This document will introduce some Basic analog electronic circuits. Page 3

4 BASIC TWO STAGE OPERATIONAL AMPLIFIER Page 4

5 SPICE ANALYSIS OF OP AMP VERSION 2.incl rit_sub_param.txt m cmosn w=9u l=5u nrd=1 nrs=1 ad=45p pd=28u as=45p ps=28u m cmosn w=9u l=5u nrd=1 nrs=1 ad=45p pd=28u as=45p ps=28u m cmosp w=21u l=5u nrd=1 nrs=1 ad=102p pd=50u as=102p ps=50u m cmosp w=21u l=5u nrd=1 nrs=1 ad=102p pd=50u as=102p ps=50u m cmosn w=40u l=5u nrd=1 nrs=1 ad=205p pd=90u as=205p ps=90u m cmosp w=190u l=5u nrd=1 nrs=1 ad=950p pd=400u as=950p ps=400u m cmosn w=190u l=5u nrd=1 nrs=1 ad=950p pd=400u as=950p ps=400u m cmosn w=40u l=5u nrd=1 nrs=1 ad=205p pd=90u as=205p ps=90u vdd vss cprobe p Rprobe 2 0 1meg cc p mr cmosp w=6u l=10u nrd=1 nrs=1 ad=200p pd=60u as=200p ps=60u mr cmosp w=6u l=10u nrd=1 nrs=1 ad=200p pd=60u as=200p ps=60u *************** ************* 13.5kV/V gain ***dc open loop gain********* vi vi *.dc vi u.dc vi m *****open loop frequency characteristics***** *vi *vi dc 0 ac 1u *.ac dec g.end Page 5

6 OPERATIONAL AMPLIFIER Page 6

7 RIT OP AMP WITH OUTPUT STAGE 99 M6 M5 M8 M11 M15 W/L 100/2 W/L 100/2 W/L 100/2 W/L 282/2 9 W/L 686/2 M19 Vin 1 40/2 M1 3 V V M2 40/2 2 Vin 7 W/L 100/2 M12 10 M16 W/L 336/2 12 M18 W/L 3800/2 14 M7 6 20/40 5 M3 90/2 4 M4 90/2 M9 30/2 8 M10 90/2 M13 30/2 M /2 M17 13 W/L 645/2 W/L 100/2 M20 W/L 2600/2 RL W/L 98 Page 7

8 OPERATIONAL AMPLIFERS The 741 Op Amp is a general purpose bipolar integrated circuit that has input bias current of 80nA, and input voltage of / 15 supply maximum of / 18 volts. The output voltage can not go all the way to the and supply voltage. At a minimum supply of / 5 volts the output voltage can go ~6 volts pp. The newer Op Amps have railrail output swing and supply voltages as low as / 1.5 volts. The MOSFET input bias currents are ~ 1pA. The NJU7031 is an example of this type of Op Amp. Page 8

9 LOW VOLTAGE, RAILTORAIL OP AMP Page 9

10 SOME BASIC ANALOG ELECTRONIC CIRCUITS These circuits should be familiar: R1 R1 R2 R2 Vin Vin = Vin R2/R1 = Vin (1 R2/R1) Inverting Amplifier NonInverting Amplifier C Vin Unity Gain Buffer = Vin Vin R = 1/RC Vin dt Integrator Page 10

11 SOME BASIC ANALOG ELECTRONIC CIRCUITS R1 V1 V2 R1 R3 Inverting Summer = ( R3/R1) (V1 V2) Rin V2 V1 Rin Rf Rf = Rf/Rin (V1V2) Difference Amplifier Page 11

12 COMPARATOR Vin V V Theoretical Vref V V Vref V Vin V Measured Page 12

13 BISTABLE CIRCUIT WITH HYSTERESIS R1 R2 V V Theoretical Vin V V TL V TH Vin V Measured Sedra and Smith pg 1187 Page 13

14 RC INTEGRATOR Va Va Vin t1 Vin t R C ut ut Va Va Smaller RC t ut = (Va) [2Va(1e t/rc )] for 0<t<t1 If R=1MEG and C=10pF find RC=10us so t1 might be ~20us Page 14

15 OSCILLATOR (MULTIVIBRATOR) R1 V T R2 V V V t1 t C V R Period = T = 2RC ln 1Vt/V 1Vt/V Bistable Circuit with Hysteresis and RC Integrator Page 15

16 PEAK DETECTOR Variable Vin C Diode reverse leakage current ~100nA Page 16

17 CAPACITORS Capacitor a two terminal device whose current is proportional to the time rate of change of the applied voltage; I = C dv/dt a capacitor C is constructed of any two conductors separated by an insulator. The capacitance of such a structure is: C = eo er Area/d d where eo is the permitivitty of free space Area er is the relative permitivitty Area is the overlap area of the two conductor separated by distance d eo = 8.85E14 F/cm er air = 1 er SiO 2 = 3.9 C I V Page 17

18 DIELECTRIC CONSTANT OF SELECTED MATERIALS Vacuum 1 Air Acetone 20 Barium strontium titanate 500 Benzene Conjugated Polymers 6 to 100,000 Ethanol 24.3 Glycerin 42.5 Glass 510 Methanol 30 Photoresist 3 Plexiglass 3.4 Polyimide 2.8 Rubber 3 Silicon 11.7 Silicon dioxide 3.9 Silicon Nitride 7.5 Teflon 2.1 Water Page 18

19 CALCULATIONS Page 19

20 DESIGN EXAMPLE Square Wave Generator RC Integrator & Capacitor Sensor Peak Detector Comparator Page 20

21 DESIGN EXAMPLE CAPACITOR SENSOR R1 R2 V V R C C Vref V C R Square Wave Generator RC Integrator & Capacitor Sensor Buffer Peak Detector Comparator Display Page 21

22 EXAMPLE LABORATORY RESULTS Smaller Capacitance Larger Capacitance Square Wave Generator Output Buffer Output Display Page 22

23 CAPACITOR MICROPHONE PLUS AMPLIFIER i R i 3.3V V C NJU = i R i = d (CV)/dt, V is constant C = Co Cm sin (2pft) i = V Cm 2 p f cos (2pft) Page 23

24 PHOTODIODE I TO V LINEAR AMPLIFIER 3.3V R1 10K I p n R2 20K 3.3V NJU R3 10K IR LED R4 100K 3.3V NJU ut 0 to 1V Gnd Gnd Page 24

25 Output ltage (V) PHOTO DIODE I TO V LOG AMPLIFIER 3.3V R1 20K IR LED I n p 3.3V NJU703 1N ut 0 to 1V Linear amplifier uses 100K ohm in place of the 1N4448 ut vs. Diode Current Gnd Gnd Linear Amplifier Log Amplifier Photodiode Diode Current (ua) Page 25

26 PHOTO DIODE I TO V INTEGRATING AMPLIFIER Reset C Internal 100 pf Ri Rf Analog ut Integrator and amplifier allow for measurement at low light levels Page 26

27 DIODE AS A TEMPERATURE SENSOR P N Poly Heater, Buried pn Diode, N Poly to Aluminum Thermocouple Compare with theoretical 2.2mV/ C Page 27

28 SIGNAL CONDITIONING FOR TEMPERATURE SENSOR 3.3V R1 20K I p n 0.2 < ut < 0.7V Gnd Page 28

29 Load I = Vs/R Load OP AMP CONSTANT CURRENT SOURCE Floating Load Grounded Load Vs Vs R1 R2 Rx R3 Rx/R1=R3/R2 R I = Vs/R2 Page 29

30 RESISTIVE PRESSURE SENSOR 5 lts 2 5 lts R1 R3 R2 R4 R1=427 R3=427 1=2.5v 2=2.5v 1 Gnd R2=427 R4=427 Resistors on a Diaphragm Gnd No Pressure 21 = 0 Page 30

31 INSTRUMENTATION AMPLIFIER R1= lts R3=426.4 V1 R1 R2 1 R3 R4 1=2.4965v R2= =2.5035v R4=427.6 V2 R2 2 R3 Gnd R4 Gnd With Pressure 21 = 0.007v =7 mv = (V2V1) R4 R3 1 2R2 R1 Page 31

32 POWER OUTPUT STAGE V V Vin V Rload V Page 32

33 REFERENCES 1. Switched Capacitor Circuits, Phillip E. Allen and Edgar SanchezSinencio, Van Nostrand Reinhold Publishers, Active Filter Design Using Operational Transconductance Amplifiers: A Tutorial, Randall L. Geiger and Edgar SanchezSinencio, IEEE Circuits and Devices Magazine, March 1985, pg Microelectronic Circuits, 5 th Edition, Sedra and Smith Page 33

34 HOMEWORK BASIC ANALOG CIRCUITS 1. Create one good homework problem and the solution related to the material covered in this document. (for next years students) 2. Design a bistable multivibrator witrh Vth of / 7.5 volts and frequency of 5 Khz. 3. Design a temperature sensor circuit that will shut down a heater if the temperature exceeds 90 C 4. Design a peak detector that will respond to changes in input in less than one second. 5. Derive the equation for the oscillator on page 15 (multivibrator). 6. Derive the voltage gain equation for the difference amplifier. Page 34

35 DERIVE GAIN EQUATION FOR DIFFERENCE AMP V2 V1 Rin Rin I Vx Rf Rf I = Rf/Rin (V1V2) I = (V1Vx)/Rin Rf Vx = V1 Rf Rin = I Rf Vx Difference Amplifier Page 35