MAX3267CSA+ Maxim Integrated, MAX3267CSA+ Datasheet - Page 6

• Manufacturer Part Number: MAX3267CSA+
• Description: Transimpedance Amplifiers
• Manufacturer: Maxim Integrated

Specifications of MAX3267CSA+

• Rohs: yes

The MAX3266 is a transimpedance amplifier designed
for 1.25Gbps fiber optic applications. Figure 2 is a func-
tional diagram of the MAX3266, which comprises a trans-
impedance amplifier, a voltage amplifier, an output
buffer, an output filter, and a DC cancellation circuit.
The MAX3267, a transimpedance amplifier designed
for 2.5Gbps fiber optic applications, shares similar
architecture with the MAX3266.
1.25Gbps/2.5Gbps, +3V to +5.5V, Low-Noise
Transimpedance Preamplifiers for LANs
Figure 1. Typical Photodiode Capacitance vs. Bias Voltage
Figure 2. MAX3266 Functional Diagram
6
_______________________________________________________________________________________
2.00
1.85
1.70
1.55
1.40
1.25
1.10
0.95
0.80
0.65
0.50
0
FILTER
IN
1
Detailed Description
REVERSE BIAS (V)
V
2
CC
1.5k
3
4
R
F
TRANSIMPEDANCE
DISABLE
5
AMPLIFIER
LOWPASS FILTER
AMPLIFIER
VOLTAGE
The signal current at the input flows into the summing
node of a high-gain amplifier. Shunt feedback through
R
imately 2.2kΩ (1.0kΩ for MAX3267). Schottky diodes
clamp the output voltage for large input currents, as
shown in Figure 3.
The voltage amplifier converts single-ended signals to
differential signals and introduces a voltage gain.
The output buffer provides a reverse-terminated volt-
age output. The buffer is designed to drive a 100Ω dif-
ferential load between OUT+ and OUT-. The output
current is divided between internal 50Ω load resistors
and the external load resistor. In the typical operating
circuit, this creates a voltage-divider with gain of 1/2.
The MAX3266 can also be terminated with higher out-
put impedances, which increases gain and output volt-
age swing.
For optimum supply-noise rejection, the MAX3266
should be terminated with a differential load. If a single-
ended output is required, the unused output should be
similarly terminated. The MAX3266 will not drive a DC-
coupled, 50Ω grounded load.
F
converts this current to a voltage with gain of approx-
DC CANCELLATION
CIRCUIT
OUTPUT
BUFFER
Transimpedance Amplifier
50Ω
50Ω
MAX3266
OUTPUT
FILTER
Voltage Amplifier
Output Buffer
OUT+
OUT-
GND
V
CC