Selected Analog Electronic Circuits Dr. Lynn Fuller

Size: px

Start display at page:

Download "Selected Analog Electronic Circuits Dr. Lynn Fuller"

Alfred Stewart
6 years ago
Views:

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

2 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 selected analog electronic circuits. Page 2

3 OUTLINE Wien Bridge Oscillator Multiplier Chip Constant Power Constant Temperature Active Filters Operational Transconductance Amplifiers Switched Capacitor Circuits References Homework Page 3

4 WIEN BRIDGE OSCILLATOR CIRCUIT CMOS Analog Circuit Design, Phillip Allen, Douglas Holbert, Holt, Rinehard and Winston. 1987, pg Page 4

5 LOOP GAIN OF WIEN BRIDGE OSCILLATOR Let R1 = R2 = R and C1 = C2 = C Loop gain G(s) = K s/rc s 2 s 3/RC (1/RC) 2 jw K/RC Loop gain G(jw) = (jw) 2 jw 3/RC (1/RC) 2 If jw = 1/RC and K = 3 then Loop gain = 1j0 and circuit will oscillate when loop is closed CMOS Analog Circuit Design, Phillip Allen, Douglas Holbert, Holt, Rinehard and Winston. 1987, pg Page 5

6 WAVEFORM GENERATOR R1 VT C R2 V V R Vo1 R Rf C Vo2 R Rf C Vo3 Vo1 SQUARE WAVE Vo2 TRIANGLE WAVE Vo3 SINE WAVE (approximation) Page 6

7 SPICE RESULTS WAVEFORM GENERATOR CIRCUIT Page 7

8 WAVEFORM GENERATORS Page 8

9 MULTIPLIER Page 9

10 MULTIPLIER AND DIVIDER CONFIGURATION Page 10

11 INTERNAL CIRCUIT SCHEMATIC FOR THE MULTIPLIER CMOS Analog Circuit Design, Phillip Allen, Douglas Holbert, Holt, Rinehard and Winston. 1987, pg Page 11

12 MULTIPLIER CHIP APPLICATIONS Multiplier Squarer Divider Square Rooter Constant Power Controller Constant Temperature Controller Voltage Controlled Amplifier Linear AM Modulator Voltage to Frequency Converter RMS to DC Converter Page 12

GAS FLOW SENSOR Upstream Polysilicon Resistor Polysilicon

(power in watts) input and two temperature measurement

At zero flow both sensors will be at the same temperature.

13 GAS FLOW SENSOR Upstream Polysilicon Resistor Polysilicon heater GAS Downstream Polysilicon Resistor Constant heat (power in watts) input and two temperature measurement resistors, one upstream, one downstream. At zero flow both sensors will be at the same temperature. Flow will cause the upstream sensor to be at a lower temperature than the down stream sensor. Page 13

14 Diode Temperature Sensor Selected Analog Electronic Circuits GAS FLOW SENSOR R1 Upstream Resistor Sensor 600ohm Heater R2 Downstream Resistor Sensor Page 14

15 FLOW SENSOR ELECTRONICS 6 Volts Constant Power Circuit for the Heater R2 Downstream Resistor 10 OHM Upstream Resistor R1 Vout Gnd 6 Volts Vout near Zero so that it can be amplified AD534 PLAY STOP Page 15

16 ANEMOMETER A single resistor with enough power dissipation will self heat to some value. At this elevated temperature the resistance normally increases. As fluid flows across the resistor the heat is carried away. King s law gives a relationship between the fluid velocity and fluid temperature, power in the heater and the temperature of the heater. If the temperature of the heater is kept constant and the fluid temperature is known the fluid velocity can be found from the power to the heater. (calibration parameters a, b, n) R Units of flow: sccm = standard cubic cm per min. Slm = standard liter per min. Flow = v f x Area V f = Power (Ts Tf) b a 1/n King s Law Page 16

ANEMOMETER CHARACTERIZATION Resistive Heater on Diaphragm With integrated diode temperature sensor 0.004 0.003 0.

17 ANEMOMETER CHARACTERIZATION Resistive Heater on Diaphragm With integrated diode temperature sensor I Cold Hot V Diode Temperature Measurement R = ρ L/(W xj) ohms ρ = 1/( qµ n n qµ p p) L,W,xj do not change, µn and µp changes with temperature, n and p does not change much in heavy doped semiconductors (that is, n and p is determined by doping) Page 17

18 ANEMOMETER CHARACTERIZATION V f = Power (Ts Tf) b a 1/n Page 18

19 AD534 CONSTANT TEMPERATURE CIRCUIT Setpoint R=V/I Analog Divider Using AD V I 10 Ω 9 Volts I Heater Gnd Page 19

20 WHEATSTONE BRIDGE CONSTANT TEMP CIRCUIT Page 20

21 POWER OUTPUT STAGE V V Vin V Vo Rload V Page 21

22 OPERATIONAL AMPLIFIER DC CHARACTERIZATION V=6 Vout 6 Vin Slope = Gain 0 Vout V=6 6 20mV Vos Vin 20mV Set up the HP 4145 to sweep the Vin from 20 mv to 20 mv in 0.001V steps. Measure Gain and Input offset voltage. 0 Page 22

23 MEASURED OPEN LOOP DC GAIN SMU1 100k 1k Vi 6v Vout SMU2 6v Gain = slope x 100 = 66,000 = 96 db Page 23

24 FREQUENCY RESPONSE OF AN OP AMP V Vin C1 100k 1k 100k Rb 6v 6v Vout V Adjust Rb to give Vout = zero with Vin = zero, Then use a network analyzer to collect data for Gain vs Frequency Page 24

NETWORK ANALYZER Quick Measurement Setup for 3577A Network Analyzer (by Jirachai Getpreecharsawas) Magnitude Plot: 1. Press INPUT button and select input A 2.

Press RES BW and select an appropriate frequency resolution, say 100 Hz Note: Sweep time might need to be adjusted so that it is higher than the settling time required for each Res BW, see table*

If applicable, press SWEEP TYPE button and select LOG FREQ SWEEP to display xaxis (freq) in log scale Note: You might need to readjust the frequency range again by pressing FREQ button!

25 NETWORK ANALYZER Quick Measurement Setup for 3577A Network Analyzer (by Jirachai Getpreecharsawas) Magnitude Plot: 1. Press INPUT button and select input A 2. Press DISPLY FCTN button and select LOG MAG 3. Press FREQ button and select STOP FREQ Note: Other options are also available. 4. Press AMPTD button and adjust the amplitude if necessary, say 20 dbm 5. Press RES BW and select an appropriate frequency resolution, say 100 Hz Note: Sweep time might need to be adjusted so that it is higher than the settling time required for each Res BW, see table* below. * Instruction Manual for 3577A Network Analyzer, pp If applicable, press SWEEP TYPE button and select LOG FREQ SWEEP to display xaxis (freq) in log scale Note: You might need to readjust the frequency range again by pressing FREQ button! Tip: Turning the knob will move the Marker along the trace (data readout). Network Analyzer Phase Plot: 1. Press TRACE 2 button 2. Press INPUT button and select input A 3. Press DISPLY FCTN button Rochester and select Institute PHASEof Technology 4. If needed, adjust the frequency Microelectronic range using FREQ Engineering button Obtain a plot using software Agilent Data Capture 2: 1. Go to Programs > Agilent IntuiLink > IntuiLink Data Capture Application 2. Click Instrument tab, choose 3577A if not selected, accept default setting, and click OK. 3. Click Get Data icon, the 2nd icon from the right, to open a plot window if no plot shown Page 25

26 AC TEST RESULTS ROCHESTER INSTITUTE OF TECHNOLOGY MICROELECTRONIC ENGINEERING LFF OPAMP.XLS FILE3B LOT F OPAMP TEST RESULTS Frequency Gain Vout Vin hz db V mv Gain db Op Amp Frequency Response 80 GBP = 500,000 Hz Frequency Hz Page 26

27 LOW PASS FILTER Vin R1 C2 R2 Vout Derive an expression for Vo/Vin Plot 20Log 10 (Vo/Vin) vs frequency Verify using SPICE Verify by building the circuit Vo/Vin = R2/R1 ω = 2 π f ω1 = 1/R2C2 1 1 j ω/ω1 1 SR2C2 1 f Page 27

28 HIGH PASS FILTER Vin C1 R1 R2 Vout Derive an expression for Vo/Vin Plot 20Log 10 (Vo/Vin) vs frequency Verify using SPICE Verify by building the circuit Vo/Vin = R2/R1 ω = 2 π f ω1 = 1/R1C1 j ω/ω1 1 j ω/ω1 SR1C1 SR1C1 1 f Page 28

29 GENERAL FILTER Vin C1 R1 C2 R2 Derive an expression for Vo/Vin Plot 20Log 10 (Vo/Vin) vs frequency Verify using SPICE Verify by building the circuit Vout Vo/Vin = R2/R1 SR1C1 1 SR2C2 1 ω = 2 π f ω1 = 1/R1C1, ω2 = 1/R2C2 = R2/R1 1 j ω/ω1 1 j ω/ω2 Page 29

30 COMBINATIONS OF FILTERS Vo/Vin = R2/R1 1 j ω/ω1 1 j ω/ω2 Two General Filters in series General General ω1, ω2 ω3, ω4 Vo/Vin = R2R4/R1R3 1 j ω/ω1 1 j ω/ω2 1 j ω/ω3 1 j ω/ω4 2 nd Order lowpass, highpass, bandpass, bandrejection and all pass filter Page 30

31 SKETCH OF VARIOUS FILTER FREQUENCY RESPONSE Vo/Vin = R2R4/R1R3 ω1 = ω3 < ω2 = ω4 1 j ω/ω1 1 j ω/ω2 1 j ω/ω3 1 j ω/ω4 ω2 2 = ω4 4 < ω1 1 = ω33 ω1 < ω2 < ω4 < ω3 ω2 < ω1 < ω3 < ω4 Page 31

32 OPERATIONAL TRANSCONDUCTANCE AMPLIFIER Page 32

33 OPERATIONAL TRANSCONDUCTANCE AMPLIFIER National Semiconductor LM13700 Page 33

34 OPERATIONAL TRANSCONDUCTANCE AMPLIFIER V Va Vb Iout M3 2 M4 M3 M4 Va Vb V Ibias Iout gm(vavb) 5 V 12/30 12/30 Vin M5 M1 M2 12/30 12/30 Vref Ibias 1 12/30 V CMOS Realization 4 Vin 12/30 Note: gm is set by Ibias Iout Page 34

35 BIQUAD FILTER V V V g m1 gm2 g m3 Vout VA V Ibias1 V Ibias2 V V Ibias3 V VB C1 g m4 g m5 C2 V Ibias5 VC V Ibias4 Page 35

36 BIQUAD FILTER V out = (s 2 C 1 C 2 V c s C 1 g m4 V b g m2 g m5 V a )/(s 2 C 1 C 2 sc 1 g m3 g m2 g m1 ) This filter can be used as a lowpass, highpass, bandpass, bandrejection and all pass filter. Depending on the C and gm values a Butterworth, Chebyshev, Elliptic or any other configuration can be achieved For example: let Vc=Vb=0 and Va=Vin, also let all g m be equal, then Vout = Vin / (s 2 C 1 C 2 / g m g m sc 1 /g m 1) which is a second order low pass filter with corner frequency at ω c = g m / C 1 C 2 and Q = C 2 /C 1 Page 36

37 ELLIPTIC FILTER V V V Vout Vin VA V Ibias V Ibias V Ibias V C1 Vin 1500 R1 50 C2 VC=Vin/31 R2 V Ibias Page 37

38 COMPARISON OF DIFFERENT FILTER DESIGNS gain Lowpass Filters Butterworth is flat in the band pass region, has the least steep transition to band stop region Elliptic Butterworth Chebychev Chebychev is not flat in the band pass region, has a steeper transition to band stop region than Butterworth frequency Elliptic is flat in the band pass region, has the steepest transition to band stop region but has some gain in the band stop region Page 38

39 SWITCHED CAPACITOR CIRCUITS Switched capacitor circuits makes use of analog switches and capacitors to replace resistors. Saves space compared to using resistors Low pass filter, filters out high frequency switching artifacts Page 39

40 SWITCHED CAPACITOR EQUIVALENT RESISTOR S1 I S2 I V1 C V2 V1 R V2 I = Cfs (V1V2) I = (1/R) (V1V2) S1 closed C charges to V1, charge transferred is Q = CV1 S1 is opened S2 is closed C charges to V2, charge transferred is Q = CV2 if the switches operate at a switching frequency fs, then I = Qfs = Cfs(V1V2) and Req = 1/(Cfs) Page 40

41 SWITCHED CAPACITOR CIRCUITS 1. The sampling frequency fs must be much higher than the signal frequencies 2. The voltages at node 1 and 2 must be unaffected by switch closures. 3. The switches are ideal. 4. S1 and S2 are not both on at same time. (use non overlapping clocks) I I S1 S2 V1 V2 C Req = 1/(Cfs) V1 R V2 I = (1/R) (V1V2) Example: for audio applications with frequencies up to 10KHz, we select switch frequency of 500KHz, for a 1 MEG ohm resistor we find that C = 1/ (500K 1MEG) = 2 p/f If Xox = 4000 Å, then the capacitor will be about 150 µm by 150 µm Page 41

42 LMF100 SWITCHED CAPACITOR FILTER CHIP Page 42

43 CHEBYCHEV FILTER EXAMPLE USING LMF100 From LMF100 Data Sheet Page 43

44 SWITCHED CAPACITOR AMPLIFIER Q = CV Φ1 Vin Φ1 Φ2 Cx Cf Vo Vo = Vin Cx/Cf Page 44

45 CAPACITOR SENSOR TO DC VOLTAGE Q = CV Φ1 Vin Φ1 Φ2 Cx Cf Low Pass Filter Vo Vo = Vin Cx/Cf Page 45

46 CAPACITANCE MEASUREMENT CIRCUIT SIMULATION Cf SPICE SIMULATION Cx Vo = Vin (CxCA) / Cf Page 46

47 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 4. CMOS Analog Circuit Design, Phillip Allen, Douglas Holbert, Holt, Rinehard and Winston, 1987, pg AsingleSupply OpAmp Circuit Collection, Texas Instruments, Application Report SLOA058November Op Amp Circuit Collection, National Semiconductor, Application Note 31, September Page 47

48 HOMEWORK SELECTED 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 high pass filter to have a gain of 100 and corner frequency of 10Mhz. 3. You have a 10pf switched capacitor equivalent resistor. What frequency is required to give an equivalent resistance of 10Mohm. 4. Design a bandpass filter to pass frequencies of 2K to 10Khz. Page 48

Selected Filter Circuits Dr. Lynn Fuller

Selected Filter Circuits Dr. Lynn Fuller ROCHESTER INSTITUTE OF TECHNOLOGY MICROELECTRONIC ENGINEERING Dr. Lynn Fuller Webpage: http://people.rit.edu/lffeee Electrical and 82 Lomb Memorial Drive Rochester, NY 146235604 Tel (585) 4752035 Email: