MAX3748HETETG16 Maxim Integrated Products, Inc., MAX3748HETETG16 Datasheet - Page 7

• Manufacturer Part Number: MAX3748HETETG16
• Description: Max3748, Max3748a, Max3748b Compact 155mbps To 4.25gbps Limiting Amplifier
• Manufacturer: Maxim Integrated Products, Inc.

The limiting amplifier consists of an input buffer, a multi-
stage amplifier, offset correction circuitry, an output
buffer, power-detection circuitry, and signal-detect cir-
cuitry (see Functional Diagram).
The input buffer is shown in Figure 3. It provides 50Ω
termination for each input signal IN+ and IN-. The
MAX3748/MAX3748A/MAX3748B can be DC- or AC-
coupled to a TIA (TIA output offset degrades receiver
performance if DC-coupled). The MAX3748/MAX3748A
CML input buffers are optimized for the MAX3744 TIA.
The high-bandwidth gain stage provides approximately
53dB of gain.
The MAX3748/MAX3748A/MAX3748B are susceptible
to DC offsets in the signal path because they have high
gain. In communication systems using NRZ data with a
50% duty cycle, pulse-width distortion present in the
signal or generated in the transimpedance amplifier
appears as an input offset and is reduced by the offset
correction loop. For Gigabit Ethernet and Fibre Channel
Figure 1. Power-Supply Current Measurement
_______________________________________________________________________________________________________
V
CC
MAX3748A/
MAX3748B
MAX3748/
I
CC
(SUPPLY CURRENT)
50Ω
Detailed Description
Offset Correction Loop
50Ω
R
TH
Input Buffer
Compact 155Mbps to 4.25Gbps
I
OUTPUT CURRENT)
Gain Stage
OUT
(CML
applications, no capacitor is required. For SONET
applications, C
capacitor determines the lower 3dB frequency of the
data path.
Figure 2. LOS Deassert Threshold Set 1dB Below the Minimum
by Receiver Sensitivity (for Selected R
Figure 3. CML Input Buffer
IN+
IN-
0.25pF
0.25pF
0V
V
IN
STRUCTURES
1dB
6dB
ESD
Limiting Amplifier
POWER-DETECT WINDOW
AZ
MAX DEASSERT LEVEL
MIN DEASSERT LEVEL
= 0.1µF is recommended. This
SIGNAL ON
50Ω
V
CC
50Ω
TH
)
75kΩ
SIGNAL OFF
TIME
7