1. Commonly used shaping circuits are (Schmidt trigger) and (monostable trigger); (Schmidt trigger) is mainly used to transform slow-changing non-rectangular pulses into steep rectangular pulses, and (monostable trigger) is mainly used to transform pulses with unsatisfactory width into rectangular pulses that meet the requirements.

2. The logic function and circuit structure of 2.PLD can be converted by programming and downloading. Spld includes programmable RAM (PRAM) and pal.pla.gal

3. The four processes of A/D conversion are sampling, holding 3.A/D quantization. Modular coding; The frequency of sampling pulse is at least twice the highest effective frequency of analog signal;

2.74283 Four-bit adder and gate circuit design a four-bit binary subtraction circuit.

First of all, 74283 is a four-bit carry full adder, which can add two four-bit binary numbers.

Secondly, with complement, subtraction can be realized by addition.

A-B=C is realized by addition: (a) complement +(B) complement =(C) complement.

Note here that the result of addition operation is the complement of C.

Thirdly, the way to find the complement is to invert the original code bit by bit and add 1. If it is realized by a circuit, negate it with a NOT gate, and then add 1 by setting the C0 pin of 74283 as 1(C0 is a low-order carry signal, which is used to add 1 here).

Note: (1) The result obtained by this method is the complement, that is, the result C is obtained by finding A-B=C originally. What we get here is the complement of (c), that is, the complement of c (2) is a circuit part with one bit in the figure and C0 terminated at a high level, and other circuit parts can be supplemented by themselves.