Shelezyaka - ADC izngutri: simple analogotsifrovoy converter.

<b>Shelezyaka</b> - ADC izngutri: simple analogotsifrovoy converter.

   SIMPLE ANALOGOTSIFROVOY

       CONVERTER

 The simplest ADC can be constructed by
scheme shown in Figure 1. Input
voltage that can vary
range from zero to supply voltage (Un) appears at the outputs 
of the converter in a parallel additional binary code (Figure 
1). For normal operation of the ADC invertorykomparatory A1-A4 
have to switch when the voltage on their inputs equal

Un / 2, and the output voltage comparators
in stable states must be
close to zero and the Un. In addition, the comparator should 
have high input and low output impedance. Satisfy these 
requirements Most modern OS, inverting input is connected to 
the potential Un / 2. 



 If the required
Accuracy 1
analogotsifrovogo
transformations do not
exceed four
bits, then as a basis for
ADC can be used quad
CMOS logic
elements of the "AND-NOT" or
"NOR." One of the
options such
device is shown in Fig. 2.
Its input
resistance around
22 ohms, and the time
transformation - not
more than 300 ns.
Domestic analog circuits
4001 is
K176LE5 and 4011 - K176LA7.

"Wireless World" (England), May. 1981.
p.1544
 Text taken from one amateur radio
site - can not remember what: (


       Analog / digital

       converter

      Bit Type

 Block diagram of the converter
shown in Fig. 3.



 Consider the order of execution of actions in the converter 
(see Fig. 3).  Clock pulse sets flip-flop

Tgn in state 1, the other triggers
Tgn1, ... Tgn-1 to 0. Same
pulse simultaneous recording unit in a high bit shift register 
RG and the n-th output register level appears log. 1. The 
comparator compares with Uin Uos corresponding available at 
this time the number in the register number, and when the 
Conditions Uin