Digital Signal Processing Reference
In-Depth Information
15
10
Ideal equalizer
5
0
−
5
−
10
Nonideal channel
15
−
0
0.5
1
1.5
2
2.5
3
3.5
4
Frequency (GHz)
(a)
4
Ideal equaliz
e
r
3
2
1
0
−
1
−
2
−
3
Nonideal channel
1
−
4
0
2
3
4
Frequency (GHz)
(b)
Figure 12-12
Transfer function of an ideal equalizer: (a) magnitude; (b) phase.
which we discuss in subsequent sections. CTLEs do not require digital devices
for implementation but are constructed from simple analog components, both
passive (resistors, capacitors, inductors) and active (amplifiers). In this section
we use the CTLE to expand on our previous discussion of equalizer behaviors,
and we develop an understanding of their operation through the presentation of
some representative designs.
12.2.1 Passive CTLEs
An example of a passive CTLE is shown in Figure 12-15. As the name suggests,
this type of equalizer does not amplify any components of the signal that pass
through it. Instead, to achieve the desired high-pass effect the equalizer attenuates
the low-frequency signal components. The main sections of the equalizer are the
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