Chapter 3 Logic Gate Circuit
[Question 3.1] Multiple choice question
1. When the three-state gate outputs a high-impedance state, is the correct statement.
A. The pointer does not move when measuring with a voltmeter B. It is equivalent to hanging in the air
C. The voltage is neither high nor low D. The pointer when measuring resistance does not move
2 . The following circuits can implement the "wired AND" function.
A.NAND gate B.Three-state output gate
C.Open collector gate D.Open drain gate
3. The following circuits are commonly used in bus applications.
A.TSL gate B.OC gate C.Open-drain gate D.CMOS NAND gate
4. When the transistor is used as a switch, the switching speed must be increased.
A. Reduce the saturation depth B. Increase the saturation depth
C. Use an active leakage circuit D. Use an anti-saturation transistor
5. In the positive logic system of the TTL circuit, the following various inputs are equivalent to the input logic "1".
A. Leave in the air B. Connect to the power supply through a resistor of 2.7kΩ
C. Connect to the ground through a resistor of 2.7kΩ D. Connect to the ground through a resistor of 510Ω
6. For the processing of the idle input terminal of the TTL NAND gate, you can.
A. Connect to the power supply B. Connect to the power supply through a 3kΩ resistor
C. Ground D. Connect in parallel with the useful input terminal
7. The outstanding advantages of CMOS digital integrated circuits compared with TTL digital integrated circuits are.
A. Micro power consumption B. High speed C. High anti-interference ability D. Wide power range
8. The logical expression Y=AB can be realized using .
A. Positive OR gate B. Positive NOT gate C. Positive AND gate
9. To make the TTL NAND gate work in the transition area, the input terminal can be connected to an external resistor RI to ground.
A.＞RON B.＜ROFF C.ROFF＜RI＜RON D.＞ROFF
10. The international standard model corresponding to the CT4000 series is .
A.CT74S Schottky series B. CT74LS low-power Schottky series
C.CT74L low-power series D. CT74H high-speed series
[Question 3.2] True/false question (mark √ if correct, × if incorrect)
1. The redundant input terminal of the TTL NAND gate can be connected to a fixed high level. ( )
2. When the input terminal of the TTL NAND gate is left floating, it is equivalent to the input being logic 1. ( )
3. The output terminals of ordinary logic gate circuits cannot be connected in parallel, otherwise the device may be damaged. ( )
4． The output terminals of the CMOS OD gate (open-drain gate) can be directly connected to achieve a wired AND. ( )
5. The logic functions of CMOS NOR gate and TTL NOR gate are exactly the same. ( )
6． The three states of the three-state gate are: high level, low level, and neither high nor low voltage. ( )
7． The output terminals of the TTL OC gate (open collector gate) can be directly connected to achieve a wired AND. ( )
8. Generally, the output terminals of TTL gate circuits can be directly connected to achieve wired AND. ( )
9. The logic functions of the two-input four-NAND gate devices 74LS00 and 7400 are exactly the same. ( )
10. When the TTL open collector gate output is 1, the output current is provided by the external power supply and resistor. ( )
11. The output terminals of the TTL OC gate (open collector gate) can be directly connected to achieve a wired AND.
( )
[Question 3.3] Fill in the blanks
1. The English abbreviation of the open collector gate is gate, and must be added when working.
2. The OC gate is called a gate, and the output terminals of multiple OC gates can be connected in parallel to achieve the function.
3． The TTL NAND gate voltage transfer characteristic curve is divided into area, area, area and area.
4. Integrated logic gate circuits mainly include circuits and circuits.
5. When the TTL NAND gate is unloaded, the output high level is V, the output low level is V, and the threshold voltage Vth is approximately V.
6. Unused input terminals in CMOS gate circuits are not allowed. In a CMOS circuit, connecting the input terminal to ground through a large resistor is equivalent to connecting to . And connecting Vdd through a resistor is equivalent to connecting to .
7. The TTL NAND gate is a pole-type integrated circuit, which is composed of and the circuit works in the state.
8.CMOS logic gate is a polar type integrated circuit, which is composed of tubes. The circuit works in the state.
[Question 3.4] The diode gate circuit is as shown in the figure. It is known that the conduction voltage drop of diodes VD1 and VD2 is 0.7V. Try to answer the following questions:
(1) A connection 10V, when B is connected to 0.3V, how many volts is the output VO
?
(2) A and B are both connected to 10V. How many volts is VO?
(3) Connect A to 10V and leave B floating. Use a multimeter to measure the voltage at terminal B
. How many volts is VB?
(4) A is connected to 0.3V and B is left floating. How many volts should be measured when VB is measured?
[Question 3.5] For the various circuits shown in Figure (a) and the input waveforms shown in Figure (b), try to draw the waveforms F1 to F4.
Figure (a) Figure (b)
[Question 3.6] The main parameters of a certain TTL inverter are IIH=20?A, IIL=1.4mA; IOH=400? A, IOL=14mA, how many similar gates can it carry?
[Question 3.7] In the circuit shown in Figure (a), when the voltage waveform shown in Figure (b) is input, try to draw the waveform of Y and write the logical expression.
Figure (a) Figure (b)
[Question 3.8] Try to explain which of the following gate circuits can be used in parallel with the output terminals (the states of the input terminals are not necessarily the same)< /p>
(1) TTL gate circuit with push-pull output stage;
(2) OC gate in TTL gate circuit;
(3) TTL gate circuit The three output gates;
(4) Ordinary CMOS gates;
(5) Open-drain output CMOS gate circuit;
(6) Three-state output gate of CMOS gate circuit.
[Question 3.9] Analyze the CMOS gate circuit shown in the figure, which ones can work normally and which ones cannot, and write the logical expression of the output signal of the circuit that can work normally.
(a) (b)
(c) (d)
(e) (f)
Skill questions
p>
[Question 3.10] There is a workshop. Two indicator lights, red and yellow, are used to indicate the working conditions of three pieces of equipment. If one piece of equipment fails, the yellow light will turn on; if two pieces of equipment fail, the red light will turn on. On; if three devices fail, the red light and yellow light will light up at the same time.
Use NAND gates and XOR gates to design a logic circuit that can achieve this requirement.
[Question 3.11] Use NAND gates to design a voting circuit for 4 people A, B, C, and D. When voting on a proposal, most people agree and the proposal passes, and A and B have equal veto rights. .
Answers to Chapter 3
[Question 3.1] Multiple choice questions
1. ABD 2. CD 3. A 4. ACD 5. ABC 6. ABD 7 . ACD
8. C 9. C 10. B
[Question 3.2] True or False Question
1.√ 2.√ 3.√ 4.√ 5.√ 6.× 7.√
8.× 9. √ 10. √ 11. √
[Question 3.3] Fill in the blanks
1. OC power supply load
2. Open collector gate line and
3. Saturation zone, turning zone, linear zone, cut-off zone