electronics principles & applications fifth edition chapter 13 integrated circuits ©1999...
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ElectronicsElectronics
Principles & ApplicationsPrinciples & ApplicationsFifth EditionFifth Edition
Chapter 13Integrated Circuits
©1999 Glencoe/McGraw-Hill
Charles A. Schuler
• IC fabrication• The 555 Timer• Additional ICs• Digital Signal Processing• Troubleshooting
INTRODUCTION
The base process is called photolithography.
• Silicon wafer (the substrate) oxidized on its surface
• Coated with photoresist
• Covered with a photomask
• Exposed to light and developed
• Etched to expose the substrate
• Impurity diffusion into the substrate
• Repeat five or more times
Silicon substrate
Start with a silicon substrateCoat with silicon dioxideCoat with photoresistCover with photomaskExpose with lightDevelopEtchDiffusion
Dopant
A PN junction has formed
Batch processing
Each wafer will yield dozens of ICs (or more).
Probetest
During the probe test, the defective ICs are marked.
After the wafer is scribed and separated,the defective ICs are discarded.
Using photolithography to form an NPN BJT
1. P-type substrate
2. N+ diffusion layer
3. N epitaxial layer
4. Silicon dioxide layer
5. Expose and etch
6. Boron diffusion
7. Silicon dioxide layer
8. Expose and etch
9. Boron base diffusion
10. Emitter diffusion
Using photolithography to form an NPN BJT
11. Coat, expose and etch
12. Aluminum metalization layer
13. Coat, expose and etch away extra aluminum
Collector contact Emitter contact
Base contact
IC fabrication quiz
The base process in making monolithic ICsis _______________. photolithography
The wafer is coated with photoresist andexposed through a _________. photomask
Etching produces windows through whichimpurities are ________. diffused
The electrical performance of each chip on thewafer is checked during the ____ test. probe
Individual sections are electrically connectedwith a film of __________. aluminum
5 k
R
S Q
Q5 k
5 k
Gnd1
Out
3
+VCC8Discharge
Threshold
Control
Trigger
7
6
5
2
555555
Reset4
UTP VCC
LTP VCC
A popular timer IC
SRQ
Q
R
S Q
Q
How the RS flip-flop in the 555 timer works:
Once set, the Q output remainshigh until the flip-flop is reset.
Outputs are inopposite states.
1
3
+VCC
7
6
2
8One-shot operation
R
C
VCC
The input trigger resets the flip-flop and C then chargesuntil the top comparator trips and sets the flip-flop.
SR
input triggeroutput pulse
Dischargetransistor
+ VCC
555
48
7
6
1
3
2
R
C
t = 1.1RCOutput pulse
Trigger1/3 VCC
The external components determine the output pulse width.
1
3
+VCC
7
6
2
8
Free-running orastable operationRB
C
RA
SR
VCC
VCC
C charges through RA+ RB
and discharges through RB.
+ VCC
555
48
7
6
1
3
2
RA
C
Astablemode duty
cycle > 50%
RB
f =1.45
(RA + 2RB)C
Duty Cycle = RA + 2RB
x 100%RA + RB
+ VCC
555
48
7
6
1
3
2
RA
C
Astablemode duty
cycle < 50%
RB
f =1.45
(RA + RB)C
RADuty Cycle =
RA + RB
x 100%
C chargesthrough RA
and dischargesthrough RB.
+ VCC
555
48
6
1
3
2
R
C
Trigger
Time-delaymode
Time delay = 1.1 RCOutput
555 timer quiz
The voltage of the trigger signal must beless than _________. VCC
The threshold and trigger comparatorscontrol the ___________. RS flip-flop
The Q output of the RS flip-flop controlsthe __________ transistor. discharge
In one-shot mode, the external R and C setthe _______ of the output pulse. width
In astable mode, the 555 timer acts as an____________. oscillator
ErrorAmplifier
Phasedetector
LPF
VCO
Phase-locked loop
In
In
VCO
The VCO locks onto the input phase.
ErrorAmplifier
Phasedetector
LPF
VCO
In
The VCO also locks onto the input frequency.
Out
Ou
tpu
t vo
ltag
e
Input frequency
Lock range
ErrorAmplifier
Phasedetector
LPF
VCO
In
PLLs can serve as FM detectors.
Out
ErrorAmplifier
Phasedetector
LPF
VCO
fREF
PLL frequency synthesizer
fOUT
Digitaldivide by N fOUT = N(fREF)
DSP can replace several types of analog circuits
• Filters
• Noise reduction circuits
• Interference reduction circuits
• Compressors and expanders
• Modulators and demodulators
• Special effects circuits
• Echo canceling circuits
MemoryA/Dconverter
Sample& hold
LPFD/Aconverter
Processor
Digital signal processing
01101110110010001100001001101110000011100000100101101110
In
MemoryA/Dconverter
Sample& hold
LPFD/Aconverter
Processor
Digital signal processing
01101110110010001100001001101110000011100000100101101110
In
01100010110010111100001001101011000011100001100101101111
Out
4-bit D/A converter
Vout
R R
2R
4R
8R
Output states = 2N = 24 = 16
N = 4
5 V8
5 V0 V
-9.375 V
Troubleshooting
• Be sure to take a system point-of-view
• Supply voltages may be critical
• Waveform analysis is often used
• Sampling/clock rate in DSP is important
• The software and/or coefficients are critical in DSP systems
• Check A/D and D/A converters
IC applications quiz
When a PLL is locked, the VCO tracks theinput _________. signal
PLLs can be used as FM _________.detectors
With a divide by N, a PLL serves as afrequency _____________. synthesizer
In DSP systems, analog signals are firstconverted to _______ signals. digital
The output of a 6-bit D/A converter has_______ possible output levels. 64
REVIEW
• Fabrication• The 555 Timer• Additional ICs• Digital Signal Processing• Troubleshooting
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