Digital Signal Processing Reference
In-Depth Information
20
10
0
−10
−20
10
0
10
1
10
2
10
3
90
0
Integrator 1
Integrator 2
Adder
−90
−180
10
0
10
1
10
2
10
3
Freq [Hz]
Fig. 4.6
Measured transfer curves of the three consecutive filter stages of the 2
nd
-order filter. The
transfer function of the first integrator also corresponds to the 1
t
-order analog filter
Clk
p
V
in,p
Latch
V
in,n
Clk
n
V
out,p
Latch
V
out,n
Fig. 4.7
Schematic view of the comparator that is employed in the
ADC
considered from a fully analog point of view. The more gain the comparator has,
the better the digitization of the filtered signal and the more accurate the digital
output of the converter. As a consequence the lower boundary for the gain in the
comparator is determined by the desired accuracy of the ADC. This boundary is
given by the presupposed signal-to-noise ratio (SNR) of the ADC. Since the applied
organic electronics technologies are unipolar it is not obvious to make a comparator
