02015-BRF-001-A Datasheet, PDF (1/2 Pages) M/A-COM Technology Solutions, Inc. – 2.5 Gbps Transimpedance Amplifier with AGC

®
2.5 Gbps Transimpedance Amplifier with AGC
M02015
Low-power, high-sensitivity 2.5 Gbps transimped-
ance amplifier fabricated in sub-micron CMOS
> KEY FEATURES
> Typical -26 dBm sensitivity, > Maximum jitter of 70 ps p-p
The M02015 transimpedance amplifier (TIA) with automatic
gain control (AGC) is fabricated in sub-micron CMOS for high
performance. With typical transimpedance of 9k ohms
differential and input-referred noise of 280na, sensitivities
of -26 dbm are achievable. With an input overload capability
greater than 6ma p-p, the AGC allows more than 32 dB of
dynamic range, providing a low-cost solution for longer-reach
> +6 dBm saturation at 2.5
Gbps
> Bandwidth 1.8 Ghz (typical)
> Input-referred noise of
280na (typical)
> Overload of 6ma p-p
> Typical differential transim-
pedance: 9kΩ
> Differential 100Ω output
impedance
> Operates on a single 3.3V
supply
> Monitor output
> AGC provides dynamic
range of more than 32 dB
2.5 Gbps GPON/ATM/SONET systems, as well as multi-rate
1X/2X Fibre-channel and Gigabit Ethernet transceivers.
For optimum system performance, the M02015 die should be
mounted with a silicon or InGaAs PIN photodetector inside a
lensed TO-Can or other optical sub-assembly.
Transimpedance Amplifier (TIA)
The TIA consists of a high gain single-ended CMOS amplifier
with a feedback resistor. The feedback creates a virtual low
impedance at the input, and nearly all of the input current
passes through the feedback resistor, defining the voltage at
the output. Advanced CMOS design techniques are employed
to maintain the stability of this stage across all input condi-
tions. An on-chip low dropout linear regulator has been incor-
porated into the design to give excellent noise rejection up to
several MHz. Higher frequency power supply noise is removed
by the external 470 pF decoupling capacitor connected to
PINK.
The circuit is intended to be configured for use with PIN
photodiodes in the “grounded cathode” configuration with
the anode connected to the input of the TIA and the cathode
connected to the PINK terminal. The PINK terminal provides a
~2.6V Reverse DC bias to reduce the photodiode capacitance.
Operation with an external bias supply to a higher potential
than 2.6V is possible, as required by avalanche photodiodes.
Automatic Gain Control (AGC)
The M02015 has been designed to operate over the input
range of +6 dBm to –26 dBm @ 2.5 Gbps. The AGC operates
on signals greater than ~ 30ua p-p. The AGC pad allows the
AGC to be disabled during photodiode alignment by grounding
the pad through a low impedance. The AGC control voltage
can be monitored during normal operation at this pad by a
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