logic_families

1. Digital ElectronicsDigital Electronics
Logic Families
TTL and CMOS

2. Logic Families CompetenciesLogic Families Competencies
61. Without references the student will state what the
acronym TTL stands for with 100% accuracy.
62. Without references the student will state the voltage
levels acceptable to a TTL input for a logic “0” and a logic
“1” with 100% accuracy.
63. Without references the student will state what the
acronym CMOS stands for with 100% accuracy.
64. Without references the student will state the voltage
levels acceptable to a CMOS input for a logic “0” and a logic
“1” with 100% accuracy.
65. Without references, the student will list three
differences between the TTL and CMOS logic families with
100% accuracy.
66. Without references the student will state what the
acronym ECL stands for with 100% accuracy.

3. Logic Families VocabularyLogic Families Vocabulary
TTL (Transistor Transistor Logic) Integrated-circuit technology that
uses the bipolar transistor as the principal circuit element.
CMOS (Complimentary Metal Oxide Semiconductor) Integrated-circuit
technology that uses the field-effect transistor as the principal circuit element.
ECL (Emitter Coupled Logic) Integrated-circuit technology that uses the
bipolar transistors configured as a differential amplifier. This eliminates
saturation and improves speed but uses more power than other families.

4. DIODE TRANSISTOR LOGICDIODE TRANSISTOR LOGIC
Y
What logicfunctionisthiscircuit?
11
01
10
00
YAA
FILL IN THE TRUTH TABLE
DIODE TRANSISTOR LOGIC
B
A
0V
0V
+V
5V
DIODE
DIODE
MMBT3904
1k
1k

9. LOGIC LEVELS / NOISE MARGIN
• Voltage characteristic - defines logical 0
(LOW) or logical 1 (HIGH)
• Noise immunity (noise margin)- logic circuit’s
insensitivity or resistance to undesired
voltages called “noise.”
Input Output
2.0 - 5.5V
LOW GND - 0.8V
HIGH 2.4 - 5.5V (3.5V typical)
GND - 0.4V (0.1V typical)
TTL Voltage Profiles Chart

10. 0%
10%
60%
50%
80%
70%
40%
30%
20%
100%
90%
HIGH
LOW
HIGH
LOW
TTL CMOS
LOW
0 to +3V for CMOS
0 to +0.8V in TTL
Input Voltage Profiles
INPUT VOLTAGE PROFILES-
TTL AND 4000 SERIES CMOS
Undefined
+3 to +7V for CMOS
+0.8V to +2.0V for TTL
Undefined
logic probe reading may
vary depending on
manufacturer
HIGH
+7V to +10V - CMOS
+2V to +5V - TTL
CAUTION
Output V profile differs
Other families V profile differs
+5V +10V
GND

11. H
Low
+5V
+2V
+0.8V
GND
INPUT
H
Low
+5V
+2.4V
+0.4V
GND
OUTPUT
? ?
Input = +4V
Output = ? ?HIGH
Input = +0.3V
Output = ? LOW
Input = +1.2V
Output = ? ?Undefined
Input = +2.2V
Output = ? ?HIGH
TTL Voltage Profiles
(Left mouse click for questions and answers)
TEST

12. OTHER DIGITAL IC SPECIFICATIONS
• Drive Capabilities- sometimes referred to as fan-in or
fan-out.
• Fan out- number of inputs of a logic family that can be
driven by a single output. The drive capability of
outputs.
• Fan in- the load an input places on an output.
• Propagation delay- has to do with the “speed” of the logic
element. Lower propagation delays mean higher speed
which is a desirable characteristic.
• Power Dissipation- generally, as propagation delays
decrease, power consumption and heat generation
increase. CMOS is noted for low power consumption.

13. MOS AND CMOS ICs
• MOS stands for metal-oxide semiconductor.
• PMOS, NMOS, and CMOS are three technologies used to
manufacture ICs.
• NMOS stands for negative-channel metal-oxide semiconductor.
NMOS ICs are faster than PMOS.
• PMOS stands for positive-channel metal-oxide semiconductor.
• CMOS stands for complementary metal-oxide semiconductor.
Both PMOS and NMOS devices are used it its manufacture.
• CMOS ICs are noted for exceptionally low power consumption.
• CMOS ICs were slower than bipolar digital ICs (such as TTL
devices).
• Transmission gates or bilateral switches are unique digital
devices created using CMOS technology.

14. 1. The drive capability of logic device outputs is
sometimes called ___ (fan in, fan out). It is the
number of inputs of a logic family that can be
driven by a single output.
(Left click mouse for questions and answers)
Fan Out
2. CMOS devices are noted for their extremely ___
(high, low) power consumption.
Low
3. A logic device with a low propagation delay
would be considered to be a ___ (high, low) speed
device.
High
4. Several desirable characteristics of logic
devices are good drive capabilities, low power
consumption, and ___ (high, low) propagation
delays.
Low
TEST

15. MOSFETMOSFET
METAL OXIDE SEMICONDUCTORMETAL OXIDE SEMICONDUCTOR
FIELD EFFECT TRANSISTORSFIELD EFFECT TRANSISTORS
P-CHANNEL ENHANCEMENTP-CHANNEL ENHANCEMENT N-CHANNEL ENHANCEMENTN-CHANNEL ENHANCEMENT
TO TURN ON GATE MUST BE
LOWER THAN SOURCE
TO TURN ON GATE MUST BE
HIGHER THAN SOURCE

16. TO TURNON
GATELOWER
THANSOURCE
D
G
S
P-MOS Vout
Vin
C-MOS
P-MOS
N-MOS
TO TURNON
GATEHIGHER
THANSOURCE
G
S
D
N-MOS0V
+V
5V
10k
0V
5V
+V
5V
+V
5V
10k
TO TURNON
GATELOWER
THANSOURCE
D
G
S
P-MOS Vin
TO TURNON
GATEHIGHER
THANSOURCE
G
S
D
N-MOS0V
+V
5V
10k
0V
5V
+V
5V
10k
MOSFETMOSFET
METAL OXIDE SEMICONDUCTORMETAL OXIDE SEMICONDUCTOR
FIELD EFFECT TRANSISTORSFIELD EFFECT TRANSISTORS

17. CMOSCMOS
COMPLIMENTARYCOMPLIMENTARY
METAL OXIDE SEMICONDUCTORMETAL OXIDE SEMICONDUCTOR

18. CMOSCMOS
COMPLIMENTARYCOMPLIMENTARY
METAL OXIDE SEMICONDUCTORMETAL OXIDE SEMICONDUCTOR
Vout
Vin
C-MOS
P-MOS
N-MOS
0V
+V
5V

19. ECLECL
EMITTER COUPLED LOGICEMITTER COUPLED LOGIC