M02139 Datasheet, PDF (8/18 Pages) M/A-COM Technology Solutions, Inc. – 1G/10G Gbps TIA with AGC and Rate Select

3.0 Functional Description
3.1
Overview
The M02139 is a 10.3 Gbps TIA with a wide input dynamic range to support different transmission distance
requirements. Input overload of 2.0 mA_PP is provided to support short-haul fiber optic systems. In order to satisfy
such high sensitivity and good optical overload requirements, automatic gain control circuit (AGC) is implemented
in the M02139. The AGC monitors the output amplitude and automatically reduces the TIA gain when the
photodiode current exceeds the AGC threshold, maintaining the output at a constant level.
A replica of the average photodiode current is available at the MON pad for photo-alignment and SFF-8472 Rx
power monitoring. A low pass filter can be engaged by pulling IMON above 1.6 V, for 1.25 Gbps operation.
Figure 3-1. M02139 Block Diagram
MON
PINK
Rf
Vreg
Voltage Reg
PINA
TIA
AGC
BGAP
VREG
Gain
Output
Buffer
DOUT
DOUT
DC
Servo
Current
Ref Gen
AGC
02139-DSH-001-D
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