1. Data Acquisition System
S/H
ADC
Transducer
AMP
Filter
Analog MUX
Transducer
AMP
Filter
Digital Interface
CPU
DAC
Translator
AMP
Filter
Data Acquisition System

2. Amplifier Gain is adjusted to occupy the vange of ADC
Dynamic range of the used signal =
Pt is used to calculate the required no of bits “n” of ADC

3. Programmable gain Amplifier
Vref R2
DAC R1 OR
Vout - + Vo Vi

4. DAC - + R0 R1 R B0 B1
V out
V ref

5. ( ) R-2R Ladder Network 2 .... . ..... V B = +
V ref - +
B n-1
2 R
V out R
B n-2
2 R R
2 R R
B 0
2 R ( ) 2
.... .
..... 1 fs
ref n
out V B = + -
* For bipolar signal, use a summer circuit to add vfs/2
* For bipolar signal, use a summer circuit to add

6. Filter
*LPF has to be used before sampling to give high attenuation at Fs/2
*Filter order is to be designed accordingly
*Higher sampling may be used in intelligent applications
( eg. Speech synthesis and recognition)
* Notch filter may be used at the mains frequency (50hz)

7. Typical filter for speech intelligent systems is shown
Amplitude
Frequency 50
100
8 k
10 k

8. Counter type ADC

9. Successive Approximation ADC