Analog Subsystems

1
Analog Subsystems
2
References

• IEEE Micro
• May 82, August 82, November 82 and February 83
• Four part tutorial by Richard Jaeger, Auburn
  University

3
12 Bit ADC to 8 Bit Bus
4
8 Bit Bus to 12 Bit DAC
5
Analog Input Front End

• Options
• function of cost and required speed i.e.
  required conversion time

6
(No Transcript)
7
(No Transcript)
8
(No Transcript)
9
Common Mode Problem
10
Common Mode Solution
11
Alternate Common Mode Solution
12
Sample-Hold Amplifiers

• Necessary when input frequency is high relative
  to ADC conversion rate

13
(No Transcript)
14
(No Transcript)
15
Switch Error
16
(No Transcript)
17
Sample-Hold Operation
18
(No Transcript)
19
Multiplexers

• Relays
• Bipolar Transistors
• MOSFET Transistors
• JFET Transistors

20
Relay
21
Relay

• Ron lt 0.1 ohm
• Roff gt109 ohm
• Vbd 105volts breakdown voltage

22
MOSFET
23
MOSFET

• Ron 5 ohms 1k ohms
• Roff gt109 ohm
• Vbd -- 50 60 volts
• Ron f(Vt)

24
JFET
25
MOSFET/JFET Circuits
26
CMOS
27
(No Transcript)
28
(No Transcript)
29
Op Amps and Circuits
30
Op Amp
31
Inverting Amplifier
32
(No Transcript)
33
Summing Amplifier
34
Noninverting Amplifier
35
Current to Voltage Converter
36
Integrator
37
(No Transcript)
38
Differential Amplifier
39
Digital to Analog Conversion
40
DAC
41
Resolution

• VFS/2n
• E.G. 12 bit and 5 volts
• Resolution is 1.221 mV

42
Ideal Transfer Characteristic
43
Discrete Codes and Voltages
44
Offset and Gain Error Effects
45
Nonlinearity Effects
46
Nonmonotonic Errors
47
DAC Types
48
Weighted Resistor DAC
49
(No Transcript)
50
Superposition Errors
51
Less Error Prone
52
Alternative
53
Inherently Monotonic DAC
54
Matched Capacitor DAC
55
(No Transcript)
56
Analog to Digital Convertors
57
ADC and Interface
58
Ideal Transfer Characteristic
59
Possible Actual Characteristic
60
Another Possibility
61
Basic Component in ADCs
62
Comparator
63
Transfer Function
64
Counter Ramp ADC
65
Counter Ramp ADC
66
(No Transcript)
67
Tracking ADC
68
Tracking ADC
69
(No Transcript)
70
Successive Approximation ADC
71
(No Transcript)
72
Single Ramp ADC
73
(No Transcript)
74
(No Transcript)
75
Dual Ramp ADC
76
(No Transcript)
77
(No Transcript)
78
Dual Ramp ADC
79
Flash ADC
80
(No Transcript)