MENG4210 Assignment 2
Operational Amplifier Noise,
Practical Transmission Lines,
Updated PCB Protection Circuit
10/04/2020
Liam Patey-Dennis
C3349900
Operational Amplifier Noise
6.
The output cutoff frequency was expected. The noise was much less than expected, I suspect that the LTspice ideal
opamp did not produce 10nV/√𝐻𝑧 and 1𝑝𝐴/√𝐻𝑧.
7.
COMPONENT
R2 Noise
NOISE
1300.0
R1 NOISE
13000.0
VOLTAGE
NOISE
RS CURRENT
NOISE
R2 CURRENT
NOISE
TOTAL
1000
0.00E+00
99999.5
100854.3
The highest component of noise is R2 which comes from current. Reduce this by reducing opamp current noise.
Figure 1 - OP27
We will compare the next opamp to this average opamp, Figure 1 - OP27. It has similar but definitely not the same
characteristics as our 10nV/√𝐻𝑧 and 1𝑝𝐴/√𝐻𝑧 question opamp. Using the Texas Instruments website, minimise the
input current and output voltage noise in the filter settings.
Figure 2 - OP392
You can see, this Op-Amp has reduced the noise almost to the ideal op-amp characteristics.
9.
The OP392 is really good at dealing with noise because it reduces the input current to 0, including current noise.
Figure 3 - OP392 Opamp Circuit
In Figure 3 - OP392 Opamp Circuit, you can see its input stage has jfet transitors, which have 0 gate current. It also
has a control feedback system that can subtract the voltage noise.
10.
From datasheet, f = 0.1 Hz to 10 Hz is 2µVpp
11.
It is possible, to create a low pass filter to dip in noise earlier.
Figure 4 - Noise vs Capacitance for 1Hz
It seems practically not feasible.
The inside of the OP392 might suggest the answer. If the inside contain control feedback system to remove noise is it
not possible to do it again, however I have not been able to demonstrate that myself.
Practical Transmission Lines
12.
Figure 5 - Normalised Load Impedance
Figure 6 – Bode Plot, Voltage Load
13.
Figure 7 - Normalised Input Impedance
Figure 8 - Frequency Sweep
Frequency sweep was same for both.
Figure 9 – Bode Plot, Input Voltage
14.
It makes no change to the smith chart plots. It does however change the Bode Plot, Input Voltage.
Figure 10 - Td = 20ns
Figure 11 - Td = 0.001ns
15.
Figure 12 - Bode (Vs-Vout)
16.
Figure 13 - Bode(Vs-Vout) Load 50Ω
17.
Not required
18.
Not required
PCB Protection Circuit with Current Sensing Capabilities
1
4
COD1
D1
1
PIR10 2
GND
PIR602
COR1
R1
6.81k 0.1%
3
3
PID203 COD2A
PID201
COQ1
Q1
1
PIQ101
PIQ102
PIQ502
PID301 COD3
PID302
PIR1 02
PIQ503
1SMA5925BT3G
1
Current Sense
PIU302
4
PIR801
Q2
MMBT3904LT1G
1
2
PIQ403COQ4
5
1
1
PIQ603
Q6
IRF9640SPBF
B
Q7
MMBT3904LT1G
PIQ701
PIQ402
PIQ702
2
GND
2.74k 0.1%
MMBT3904LT1G
Q4
PIQ401
GND
COR3
R3
PIDS302 CODS3
PIDS301
PIQ703 COQ7
DS3
LTST-C170KGKT
PIQ20
PIU105
PIQ604 COQ6
1
PIQ601
3
7
PIU107
PIQ201
1
PIU101
PIR2502
PIR301
PIR902
U1B
3
PIU103
6
PIU104
PIR1602
PIU105
COR16
R16
GND
MMBT3904LT1G
2
PIQ302
5
5.62k 0.1%
PIR501
C
GND
PIQ803
COQ8
Q8
MMBT3904LT1G
1
6.81k 0.1%
PIQ801
PIQ802
GND
2
GND
PIR160
GND
PIR2501
Q3
1
PIU106
PIQ301
4
COR5
R5
COR25
R25
212 0.1%
COR9
R9
4.32k 0.1%
PIR901
3
8
PIQ30 COQ3
LT1720IS8#PBF
3
PIU108
GND
PIR502
-
2
2
PIU102
PIR401
C
1
PIU301
4
PIU304
3
PIQ203 COQ2
LT1720IS8#PBF
3
COR2
R2
COR8
R8
100k 0.1%
3
8
PIU108
COU1A
COU1B
U1A
COR4
R4
3.32k 0.1%
COU3
U3
INA169NA/3K
GND
PIR201
PIR402
PIU305
GND
3.32k 0.1%
PIR302
COR11
R11
0.1 0.1%
+
PIR1 01
PIR802
PIR20
3
PIU303
PIR701
GND
B
PIR10 1
COQ5
Q5
1
PIQ501
D3
PIR1201
COR7
MMBT3904LT1G R7
1.21k 0.1%
D2A
BZX84C6V2LT1G
2
COR12
R12
100k 0.1%
PIR601
PIR702
PIQ103
PIR10
COR6
R6
4.75k 0.1%
A
COR10
R10
0.1 0.1%
MMBT5401LT1G
PIR120
5
PIR102
KLDX-0202-B
2
V3PAN50-M3/I
3
PIJ102 PIJ103
PID101
1
PID102
2
2
PIJ101
A
3
2
COJ1
J1
2
GND
1k 0.1%
PIU205
PIC102
COC1
C1
100k 0.1%
PIC10 1uF 10V
PIR20 2
COR18
R18
PIR1801
PIR170
GND
PIR1802
1N4148WS
GND
PIR20 1
GND
6
PIU206
PIDS201
PIR2301
PIDS202
2
PIJ201
COU4
U4
LT1716CS5#TRPBF
4
PIU404
1
LTST-C170KRKT
PIU205
COR22
R22
PIR2201
PIR2202
200k 0.1%
GND
GND
PIU401
3
PIU403
PIR2402
COR24
R24
PIC201 COC2
C2
1.21k 0.1%
PIC202 C1210C106M6PACTU
PIR2401
PIU402
GND
PIJ202
GND
KLDX-0202-B
D
Number
Revision
A4
Date:
File:
3
PIJ203
COJ2
J2
Title
Size
GND
GND
1
Output
PIU405
4
PIU204
GND
GND
COR23
R23
4.75k 0.1%
5
U2B
3
PIU203
COR20
R20
1k 0.1%
GND
CODS2
DS2
2
COR17
R17
PIR1501
D
1
PIU201
PIR1901
PIR2302
LT1720IS8#PBF
1
PIR1702
1
PID401
5
COR15
R15
10k 0.1%
7 PID402
2
PIU207
PIU208
2
2
PIU202
PIR1502
COR19
R19
2k 0.1%
8
Sense
NLCurrent
Current Sense
COU2A
COU2B
U2A
COD4
D4 LT1720IS8#PBF
5
8
PIU208
PIR1902
4/17/2024
F:\PCB Projects\..\Liam_PD.SchDoc
Sheet of
Drawn By:
4
COJ1
COD1
PAJ101
PAJ102
PAD302
COR5
COU1
PAU105
PAU104
PAR502
PAU106
PAU103
PAR501
PAU107
PAU102
PAU108
COQ3
COQ2
PAQ302 PAQ301
PAQ202 PAQ201
PAQ303
PAQ203
COQ8
PAQ803
PAQ801 PAQ802
COU4
COR8
PAR802
PAR801
COR9
COR6 PAR601 PAR602
COC2 PAC201
COQ7
PAR702
COR19 PAR1601
PAR701
PAR1902
PADS302
PADS301
PAQ401
PAQ403
CODS3
PAR1901
PAR2002
COU3
COR17
PAR1802
COR18
PAR1702
PAR1801
PAR1502
PAU204 PAU203 PAU202 PAU201
PAJ201
PAJ203
PAU301
PAR1102
PAR1101
COR25
CODS2 PAR2302
PAR2301
COD4 PADS201 PADS202
PAD401
COR23
COQ6
PAD402
COJ2
PAJ202
COR11
PAU303
PAU302
PAU305
PAR2502
PAR2501
PAR1501
PAU304
PAR1701
PAR2001
PAQ402
COR15
PAC101
PAC102
PAR1602
COR20
PAC202
COR16 COC1
COR7
PAQ702
PAU403
PAU402
PAU401
PAU405
PAR1202 PAR1201
PAR301
PAQ703
PAR901 PAR902
PAU404
PAD203
PAQ701
COQ4
COR12 PAR2202 PAR2201
PAQ101 PAQ102
COR4 PAR401 PAR402
COR3 COR2 PAR201 PAR202
PAU101
PAR1002
PAR1001
COR22
PAD202
PAR302
PAQ502
PAQ501
PAQ103
PAD201
COR10
PAQ503
COQ1
PAR101
COD2
COQ5
COR1
PAR102
PAJ103
PAD301
COD3
PAD102 PAD101
PAU205 PAU206 PAU207 PAU208
PAQ601
COU2
COR24 PAR2402 PAR2401
PAQ603
PAQ604
0