MAX3657 Datasheet, PDF (10/15 Pages) Maxim Integrated Products – 155Mbps Low-Noise Transimpedance Amplifier

155Mbps Low-Noise Transimpedance
Amplifier
Interface Schematics
Equivalent Output Interface
The MAX3657 has a differential CML output structure
with 100Ω back termination (200Ω differentially). Figure
5 is a simplified diagram of the output interface. The
output current is divided between the internal 100Ω
resistor and the external load resistance. Because of
the CML structure, the maximum output-signal ampli-
tude is affected by load impedance. Note that the inter-
nal back termination is 100Ω single ended and external
termination is recommended to interface the device to
50Ω test equipment. For example, if single-ended oper-
ation in a 50Ω system is required, first match the output
of the MAX3657 to the 50Ω controlled impedance by
placing a 100Ω pullup resistor in parallel with the out-
put. Then establish similar loading conditions on the
unused output. Note that the loading conditions affect
the overall gain of the MAX3657. Figures 6a, 6b, and 6c
show alternate interface schemes for the MAX3657.
Pad Coordinates
Table 2 lists center-pad coordinates for the MAX3657
bond pads. Refer to Maxim Application Note HFAN-
8.0.1: Understanding Bonding Coordinates and
Physical Die Size for more information on bond-pad
coordinates.
R_OUT
100Ω
V_CC
V_CC
R_OUT
100Ω
OUT+
V_CC
OUT-
4.5mA
Figure 5. Equivalent Output Interface
Table 2. Bond-Pad Information
PAD
BP1
BP2
BP3
BP4
BP5
BP6
BP7
BP8
BP9
BP10
BP11
NAME
MAX3657 MAX3657B
OUT-
OUT+
GND
GND
GNDZ
GNDZ
MON
MON
IN
IN
FILT
FILT
N.C.
N.C.
V_CCZ
V_CC
OUT+
V_CCZ
V_CC
OUT-
N.C.
N.C.
COORDINATES (µm)
X
Y
47.2
994.8
52.2
484.6
52.2
357.7
395.5
47.2
522.3
47.2
648.5
47.2
808.5
49.9
808.5
176.8
808.5
303.7
808.5
994.8
741.1
859.9
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