technology digital logic - buas-ti...digital logic dr. theo kluter technology ttl cmos technology...
TRANSCRIPT
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Technology
◮ Today all gates are implemented in semiconductor material
◮ However, the transistors used are different
◮ The two famous families are:
◮ Transistor to Transistor Logic
◮ Complementary Metal Oxide Silicon
◮ The gates come in the form of an Integrated Circuit
1
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Technology
◮ Today all gates are implemented in semiconductor material
◮ However, the transistors used are different
◮ The two famous families are:
◮ Transistor to Transistor Logic
◮ Complementary Metal Oxide Silicon
◮ The gates come in the form of an Integrated Circuit
1
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Technology
◮ Today all gates are implemented in semiconductor material
◮ However, the transistors used are different
◮ The two famous families are:
◮ Transistor to Transistor Logic
◮ Complementary Metal Oxide Silicon
◮ The gates come in the form of an Integrated Circuit
1
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Technology
◮ Today all gates are implemented in semiconductor material
◮ However, the transistors used are different
◮ The two famous families are:
◮ Transistor to Transistor Logic
◮ Complementary Metal Oxide Silicon
◮ The gates come in the form of an Integrated Circuit
1
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Technology
◮ Today all gates are implemented in semiconductor material
◮ However, the transistors used are different
◮ The two famous families are:
◮ Transistor to Transistor Logic
◮ Complementary Metal Oxide Silicon
◮ The gates come in the form of an Integrated Circuit
1
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Technology
◮ Today all gates are implemented in semiconductor material
◮ However, the transistors used are different
◮ The two famous families are:
◮ Transistor to Transistor Logic
◮ Complementary Metal Oxide Silicon
◮ The gates come in the form of an Integrated Circuit
7404
1
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Technology
◮ Today all gates are implemented in semiconductor material
◮ However, the transistors used are different
◮ The two famous families are:
◮ Transistor to Transistor Logic
◮ Complementary Metal Oxide Silicon
◮ The gates come in the form of an Integrated Circuit
Pin 1 Indicator21 3 4 5 6
14 13 12 11 10 9 8
7
7404
1
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Technology
◮ Today all gates are implemented in semiconductor material
◮ However, the transistors used are different
◮ The two famous families are:
◮ Transistor to Transistor Logic
◮ Complementary Metal Oxide Silicon
◮ The gates come in the form of an Integrated Circuit
Pin 1 Indicator21 3 4 5 6
14 13 12 11 10 9 8
7
1
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Technology
◮ Today all gates are implemented in semiconductor material
◮ However, the transistors used are different
◮ The two famous families are:
◮ Transistor to Transistor Logic
◮ Complementary Metal Oxide Silicon
◮ The gates come in the form of an Integrated Circuit
Pin 1 Indicator21 3 4 5 6
14 13 12 11 10 9 8Power supply
7 Ground
1
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Transistor to Transistor Logic
The family of TTL gates is based on circuits using:Bipolar Junction Transistor(s)
Single-ended circuit
Y
Y
Y
DIN
IECA
A
A
1
VCC
Emitter
CollectorBase
2
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Transistor to Transistor Logic
The family of TTL gates is based on circuits using:Bipolar Junction Transistor(s)
Single-ended circuit
Y
Y
Y
DIN
IECA
A
A
1
VCC
B
E
C
VCC
2
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Transistor to Transistor Logic
The family of TTL gates is based on circuits using:Bipolar Junction Transistor(s)
Single-ended circuit
Y
Y
Y
DIN
IECA
A
A
1
VCC
B
E
C
Logic gates always needa power supply!
VCC
2
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Transistor to Transistor Logic
The family of TTL gates is based on circuits using:Bipolar Junction Transistor(s)
Single-ended circuit
Y
Y
Y
DIN
IECA
A
A
1
VCC
YA
B
E
C
VCC
2
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Transistor to Transistor Logic
The family of TTL gates is based on circuits using:Bipolar Junction Transistor(s)
Single-ended circuit
Y
Y
Y
DIN
IECA
A
A
1
VCC
YA
B
E
C
VCC
0
1
2
3
0
1
2
3
Input/Output voltage [V]
time
Y
A
2
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Transistor to Transistor Logic
The family of TTL gates is based on circuits using:Bipolar Junction Transistor(s)
Single-ended circuit
Y
Y
Y
DIN
IECA
A
A
1
VCC
YA
B
E
C
VCC
0
1
2
3
0
1
2
3
Input/Output voltage [V]
time
Y
A
Fast ’0’
2
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Transistor to Transistor Logic
The family of TTL gates is based on circuits using:Bipolar Junction Transistor(s)
Single-ended circuit
Y
Y
Y
DIN
IECA
A
A
1
VCC
YA
B
E
C
VCC
0
1
2
3
0
1
2
3
Input/Output voltage [V]
time
Y
A
Fast ’0’
Slow ’1’
2
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Transistor to Transistor Logic
The family of TTL gates is based on circuits using:Bipolar Junction Transistor(s)
Single-ended special case: the open-collector circuit
Y
Y
Y
DIN
IECA
A
A
1
VCC
YA
B
E
C
2
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Transistor to Transistor Logic
The family of TTL gates is based on circuits using:Bipolar Junction Transistor(s)
Single-ended circuit
Y
Y
Y
DIN
IECA
A
A
1
VCC
YA
B
E
C
VCC
0
1
2
3
0
1
2
3
Input/Output voltage [V]
time
Y
A
Fast ’0’
Slow ’1’
2
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Transistor to Transistor Logic
The family of TTL gates is based on circuits using:Bipolar Junction Transistor(s)
Single-ended circuit
Y
Y
Y
DIN
IECA
A
A
1
VCC
YA
B
E
C
Load
VCC
0
1
2
3
0
1
2
3
Input/Output voltage [V]
time
Y
A
Fast ’0’
Slow ’1’
2
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Transistor to Transistor Logic
The family of TTL gates is based on circuits using:Bipolar Junction Transistor(s)
Single-ended circuit
Y
Y
Y
DIN
IECA
A
A
1
VCC
YB
E
C
Load
VCC
0
1
2
3
0
1
2
3
Input/Output voltage [V]
time
Y
A
Fast ’0’
Slow ’1’
2
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Transistor to Transistor Logic
The family of TTL gates is based on circuits using:Bipolar Junction Transistor(s)
Single-ended circuit
Y
Y
Y
DIN
IECA
A
A
1
VCC
Y
Loadcurrent
VCC
0
1
2
3
0
1
2
3
Input/Output voltage [V]
time
Y
A
Fast ’0’
Slow ’1’
2
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Transistor to Transistor Logic
The family of TTL gates is based on circuits using:Bipolar Junction Transistor(s)
Single-ended circuit
Y
Y
Y
DIN
IECA
A
A
1
VCC
YB
E
C
Load
VCC
0
1
2
3
0
1
2
3
Input/Output voltage [V]
time
Y
A
Fast ’0’
Slow ’1’
2
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Transistor to Transistor Logic
The family of TTL gates is based on circuits using:Bipolar Junction Transistor(s)
Single-ended circuit
Y
Y
Y
DIN
IECA
A
A
1
VCC
Y
current
VCC
0
1
2
3
0
1
2
3
Input/Output voltage [V]
time
Y
A
Fast ’0’
Slow ’1’
2
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Transistor to Transistor Logic
The family of TTL gates is based on circuits using:Bipolar Junction Transistor(s)
Push-pull circuit
Y
Y
Y
DIN
IECA
A
A
1
VCC
Y
current
VCC
0
1
2
3
0
1
2
3
Input/Output voltage [V]
time
Y
A
Fast ’0’
Fast ’1’
2
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Transistor to Transistor Logic
The family of TTL gates is based on circuits using:Bipolar Junction Transistor(s)
Push-pull circuit
Y
Y
Y
DIN
IECA
A
A
1
VCC
YA
B
E
C
B
C
E
VCC
0
1
2
3
0
1
2
3
Input/Output voltage [V]
time
Y
A
Fast ’0’
Fast ’1’
2
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Analog Aspects of Digital Logic
0
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5 3 3.5
Output voltage [V]
Input voltage [V]
YA
B
E
C
B
C
E
Y
Y
VCC
VCC
VCC
◮ In the “digital” area the circuit acts as expected◮ In the “analog” area, however, the circuits is like a short
circuit!◮ By having fast transactions (flanks) we stay as short as
possible in the “analog” area
3
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Analog Aspects of Digital Logic
0
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5 3 3.5
Output voltage [V]
Input voltage [V]
YA
B
E
C
B
C
E
Y
Y
Y
VCC
VCC
VCC
VCC
◮ In the “digital” area the circuit acts as expected◮ In the “analog” area, however, the circuits is like a short
circuit!◮ By having fast transactions (flanks) we stay as short as
possible in the “analog” area
3
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Analog Aspects of Digital Logic
0
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5 3 3.5
Output voltage [V]
Input voltage [V]
YA
B
E
C
B
C
E
Y
Y
Y
VCC
VCC
VCC
VCC
◮ In the “digital” area the circuit acts as expected◮ In the “analog” area, however, the circuits is like a short
circuit!◮ By having fast transactions (flanks) we stay as short as
possible in the “analog” area
3
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Electrical Properties of BJT’s
0
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5 3 3.5
Output voltage [V]
Input voltage [V]
1 1
B
E
C
B
C
E
A
B
E
C
B
C
E
Y Z
A Y Z
A
YA Y Z
VCCVCC
◮ The “pull” transistor is approx. 10× stronger than the“push” transistor for the same silicon area taken
◮ TTL circuits only have a small “off” range compared to the“on” range making the “pull” very important
4
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Electrical Properties of BJT’s
0
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5 3 3.5
Output voltage [V]
Input voltage [V]
1 1
B
E
C
B
C
E
A
B
E
C
B
C
E
Y Z
A Y Z
A
YA Y Z
VCCVCC
◮ The “pull” transistor is approx. 10× stronger than the“push” transistor for the same silicon area taken
◮ TTL circuits only have a small “off” range compared to the“on” range making the “pull” very important
4
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Electrical Properties of BJT’s
0
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5 3 3.5
Output voltage [V]
Input voltage [V]
1
B
E
C
B
C
E
A
B
E
C
B
C
E
Y Z
A Y Z
A
YA Y Z
the first invertorSwitching point for
1
VCCVCC
◮ The “pull” transistor is approx. 10× stronger than the“push” transistor for the same silicon area taken
◮ TTL circuits only have a small “off” range compared to the“on” range making the “pull” very important
4
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Electrical Properties of BJT’s
0
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5 3 3.5
Output voltage [V]
Input voltage [V]
Switching point forthe second invertor
B
E
C
B
C
E
A
B
E
C
B
C
E
Y Z
A Y Z
A
YA Y Z
1 1
VCCVCC
◮ The “pull” transistor is approx. 10× stronger than the“push” transistor for the same silicon area taken
◮ TTL circuits only have a small “off” range compared to the“on” range making the “pull” very important
4
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Electrical Properties of BJT’s
0
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5 3 3.5
Output voltage [V]
Input voltage [V]
B
E
C
B
C
E
A
B
E
C
B
C
E
Y Z
A Y Z
A
YA Y Z
1 1
second invertor
second invertorOn Voltage range of
Off Voltage range of
VCCVCC
◮ The “pull” transistor is approx. 10× stronger than the“push” transistor for the same silicon area taken
◮ TTL circuits only have a small “off” range compared to the“on” range making the “pull” very important
4
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
What About the other Gates
YBA
VCC
blabla
Y = A · B blabla
Y = A + B
◮ The circuit represents a NOR gate
◮ The “push” and “pull” circuits represent complementarycircuits
◮ By adding an invertor we get the OR gate
5
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
What About the other Gates
YBA
VCC
blabla
Y = A · B blabla
Y = A + B
◮ The circuit represents a NOR gate
◮ The “push” and “pull” circuits represent complementarycircuits
◮ By adding an invertor we get the OR gate
5
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
What About the other Gates
Y
AB
Y
DIN
IEC
1
BA
A
BY
VCC
YBA
VCC
blabla
Y = A · B blabla
Y = A + B
◮ The circuit represents a NOR gate
◮ The “push” and “pull” circuits represent complementarycircuits
◮ By adding an invertor we get the OR gate
5
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
What About the other Gates
Y
AB
Y
DIN
IEC
1
BA
A
BY
VCC
YBA
VCC
blabla
Y = A · B blabla
Y = A + B
◮ The circuit represents a NOR gate
◮ The “push” and “pull” circuits represent complementarycircuits
◮ By adding an invertor we get the OR gate
5
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
What About the other Gates
Y
AB
Y
DIN
IEC
1
BA
A
BY
VCC
YBA
VCC
blabla
Y = A · B blabla
Y = A + B
◮ The circuit represents a NOR gate
◮ The “push” and “pull” circuits represent complementarycircuits
◮ By adding an invertor we get the OR gate
5
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
What About the other Gates
Y
AB
Y
DIN
IEC
1
BA
A
BY
VCC
YBA
VCC
blabla
Y = A + B blabla
Y = A + B
◮ The circuit represents a NOR gate
◮ The “push” and “pull” circuits represent complementarycircuits
◮ By adding an invertor we get the OR gate
5
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
What About the other Gates
Y
AB
Y
DIN
IEC
1
BA
A
BY
VCC
YBA
VCC
blabla
Y = A + B blabla
Y = A + B
◮ The circuit represents a NOR gate
◮ The “push” and “pull” circuits represent complementarycircuits
◮ By adding an invertor we get the OR gate
5
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
What About the other Gates
Y
AB
Y
AB
Y
A
B
DIN
IEC
1
VCC
YBA
Y
VCC
blabla
Y = A · B blabla
Y = A + B
◮ The circuit represents a NOR gate
◮ The “push” and “pull” circuits represent complementarycircuits
◮ By adding an invertor we get the OR gate
5
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
What About the other Gates
&
Y
AB
Y
DIN
IEC
BA
A B
Y
VCC
BA
Y
VCC
blabla
Y = A · B blabla
Y = A · B
◮ This circuit represents the NAND gate
◮ By adding an invertor we get the AND gate
6
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
What About the other Gates
&
DIN
IEC
A B
Y
AB
Y
AB
Y
VCC
Y
BAY
VCC
blabla
Y = A · B blabla
Y = A · B
◮ This circuit represents the NAND gate
◮ By adding an invertor we get the AND gate
6
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
What About the other Gates
A B
Y
AB
Y
AB
Y
DIN
IEC
=1
VCC
A B
Y
VCC
blabla
Y = A ⊕ B blabla
◮ This circuit represents the XOR gate
◮ What about the XNOR gate?
◮ By just changing 2 connections we get an XNOR gate
7
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
What About the other Gates
A B
Y
AB
Y
AB
Y
DIN
IEC
=1
VCC
A B
Y
VCC
blabla
Y = A · B + A · B
blabla
◮ This circuit represents the XOR gate
◮ What about the XNOR gate?
◮ By just changing 2 connections we get an XNOR gate
7
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
What About the other Gates
A B
Y
AB
Y
AB
Y
DIN
IEC
=1
VCC
A B
Y
VCC
blabla
Y = A · B + A · B
blabla
Y = A · B + A · B
◮ This circuit represents the XOR gate
◮ What about the XNOR gate?
◮ By just changing 2 connections we get an XNOR gate
7
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
What About the other Gates
A B
Y
Y
AB
Y
DIN
IEC
=1
BA
VCC
A B
Y
VCC
blabla
Y = A · B + A · B
blabla
Y = A · B + A · B
◮ This circuit represents the XOR gate
◮ What about the XNOR gate?
◮ By just changing 2 connections we get an XNOR gate
7
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
Complementary Metal Oxide Silicon
The family of CMOS gates is based on circuits using:Field Effect Transistor(s)
Drain
Source
Gate
8
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
BJT versus FET
BJT
VCC
VCC
◮ The BJT requires a base current to conduct
◮ The FET requires a gate charge to conduct
9
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
BJT versus FET
BJT MOSFET
VCC
VCC
VCC
VCC
◮ The BJT requires a base current to conduct
◮ The FET requires a gate charge to conduct
9
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
BJT versus FET
Base
Emitter
Collector
Emitter
Base
Collector
Base
Emitter
Collector
Base
Collector
Emitter
BJT MOSFET
VCC
VCC
◮ The BJT requires a base current to conduct
◮ The FET requires a gate charge to conduct
9
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
BJT versus FET
BJT MOSFET
Gate
Source
Drain
Drain
Source
GateBase
Emitter
Collector
Emitter
Base
Collector
Base
Emitter
Collector
Base
Collector
Emitter
Gate
Gate
Source
Drain
Drain
Source
◮ The BJT requires a base current to conduct
◮ The FET requires a gate charge to conduct
9
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS
CMOSVCC
VCC
TTLVCC
VCC
◮ TTL is fast, as a small current already switches state
◮ CMOS is slower than TTL due to gate capacitorcharge/discharge
10
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS
CMOSVCC
VCC
TTLVCC
VCC
◮ TTL is fast, as a small current already switches state
◮ CMOS is slower than TTL due to gate capacitorcharge/discharge
10
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS
TTL CMOS0 01
VCC
VCC VCC
VCC
◮ TTL always consumes static energy; CMOS does notconsume static energy
◮ CMOS consumes less energy than TTL
11
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS
TTL CMOS0 01
no current!
VCC
VCC VCC
VCC
◮ TTL always consumes static energy; CMOS does notconsume static energy
◮ CMOS consumes less energy than TTL
11
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS
CMOS1 10
no current!
TTLVCC
VCC
VCC
VCC
◮ TTL always consumes static energy; CMOS does notconsume static energy
◮ CMOS consumes less energy than TTL
11
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS
CMOSVCC
VCC
TTLVCC
VCC
◮ TTL always consumes static energy; CMOS does notconsume static energy
◮ CMOS consumes less energy than TTL
11
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS
CMOSVCC
VCC
TTLVCC
VCC
Ene
rgy
[J]
Input voltage [V]
TTL
CMOS
◮ TTL always consumes static energy; CMOS does notconsume static energy
◮ CMOS consumes less energy than TTL
11
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS
Unused Gates
TTL CMOS
VCCVCC VCCVCC
◮ What do we do with the unused gates in an IC?
◮ By leaving a TTL gate unconnected we have a stablesituation; however, a CMOS gate starts oscillating due toenvironment noise
◮ We have to either Pull-Down the input(s)
◮ or Pull-Up the input(s)
12
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS
Unused Gates
TTL CMOS
H 0 H 0
VCCVCC VCCVCC
◮ What do we do with the unused gates in an IC?
◮ By leaving a TTL gate unconnected we have a stablesituation; however, a CMOS gate starts oscillating due toenvironment noise
◮ We have to either Pull-Down the input(s)
◮ or Pull-Up the input(s)
12
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS
Unused Gates
TTL CMOS
1 1 1 1
VCCVCC VCCVCC
◮ What do we do with the unused gates in an IC?
◮ By leaving a TTL gate unconnected we have a stablesituation; however, a CMOS gate starts oscillating due toenvironment noise
◮ We have to either Pull-Down the input(s)
◮ or Pull-Up the input(s)
12
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS
Unused Gates
TTL CMOS
0 0 0 0
VCCVCC VCCVCC
◮ What do we do with the unused gates in an IC?
◮ By leaving a TTL gate unconnected we have a stablesituation; however, a CMOS gate starts oscillating due toenvironment noise
◮ We have to either Pull-Down the input(s)
◮ or Pull-Up the input(s)
12
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS
Over and under voltage
+
−
+
−
+
−
+
−
+
−
+
−
+
−
+
−
TTL CMOS
VCCVCC VCCVCC
◮ What happens in case of over and under voltage?
◮ The TTL logic supports up to the diode breakdown voltage
◮ The CMOS logic goes quickly into Latch-Up eventuallydestroying it
13
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS
Over and under voltage
+
−
+
−
+
−
+
−
+
−
+
−
+
−
+
−
TTL CMOS
1
0
1
0
VCCVCC VCCVCC
◮ What happens in case of over and under voltage?
◮ The TTL logic supports up to the diode breakdown voltage
◮ The CMOS logic goes quickly into Latch-Up eventuallydestroying it
13
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS
ElectroStatic Discharge
TTL CMOS
VCCVCC VCCVCC
◮ The TTL gate supports it relatively good
◮ The CMOS logic is very sensible; it eventually destroys it
14
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS
ElectroStatic Discharge
TTL CMOS
VCCVCC VCCVCC
◮ The TTL gate supports it relatively good
◮ The CMOS logic is very sensible; it eventually destroys it
14
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS Summary
TTL is in many respects better than CMOS, so why are almost alldevices implemented in CMOS technology?
◮ The main reason is heat dissipation:
◮ As TTL consumes both in static and switching energy, heat isgenerated
◮ CMOS “only” consumes during switching and consumes lessthan TTL
◮ An Intel Processor implemented in a TTL technology wouldsimply “melt” at current given frequencies
◮ However, TTL is still used in combination with CMOS(=BIMOS)
15
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS Summary
TTL is in many respects better than CMOS, so why are almost alldevices implemented in CMOS technology?
◮ The main reason is heat dissipation:
◮ As TTL consumes both in static and switching energy, heat isgenerated
◮ CMOS “only” consumes during switching and consumes lessthan TTL
◮ An Intel Processor implemented in a TTL technology wouldsimply “melt” at current given frequencies
◮ However, TTL is still used in combination with CMOS(=BIMOS)
15
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS Summary
TTL is in many respects better than CMOS, so why are almost alldevices implemented in CMOS technology?
◮ The main reason is heat dissipation:
◮ As TTL consumes both in static and switching energy, heat isgenerated
◮ CMOS “only” consumes during switching and consumes lessthan TTL
◮ An Intel Processor implemented in a TTL technology wouldsimply “melt” at current given frequencies
◮ However, TTL is still used in combination with CMOS(=BIMOS)
15
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS Summary
TTL is in many respects better than CMOS, so why are almost alldevices implemented in CMOS technology?
◮ The main reason is heat dissipation:
◮ As TTL consumes both in static and switching energy, heat isgenerated
◮ CMOS “only” consumes during switching and consumes lessthan TTL
◮ An Intel Processor implemented in a TTL technology wouldsimply “melt” at current given frequencies
◮ However, TTL is still used in combination with CMOS(=BIMOS)
15
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS Summary
TTL is in many respects better than CMOS, so why are almost alldevices implemented in CMOS technology?
◮ The main reason is heat dissipation:
◮ As TTL consumes both in static and switching energy, heat isgenerated
◮ CMOS “only” consumes during switching and consumes lessthan TTL
◮ An Intel Processor implemented in a TTL technology wouldsimply “melt” at current given frequencies
◮ However, TTL is still used in combination with CMOS(=BIMOS)
15
Digital Logic
Dr. Theo Kluter
Technology
TTL
CMOS
TTL versus CMOS Summary
TTL is in many respects better than CMOS, so why are almost alldevices implemented in CMOS technology?
◮ The main reason is heat dissipation:
◮ As TTL consumes both in static and switching energy, heat isgenerated
◮ CMOS “only” consumes during switching and consumes lessthan TTL
◮ An Intel Processor implemented in a TTL technology wouldsimply “melt” at current given frequencies
◮ However, TTL is still used in combination with CMOS(=BIMOS)
15