QDFB
Wide Dynamic Range
pinFET Receiver
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Telecom access and junction applications
Transimpedance amplifier with AGC
High sensitivity
Wide dynamic range >32 dB
1300 and 1550 nm operation
Description
The QDFB is a fiber-optic transimpedance receiver used in long-wavelength applications.
Excellent sensitivity and a wide dynamic range are achieved by the use of an automatic
gain control circuit (AGC). The QDFB features a buffered output stage which increases the
drive capabilities. Packaged in the industry-standard, low-profile 14-pin DIL package, the
hermetic package is pigtailed with multimode fiber. Connector selection is optional.
Applications
The QDFB pinFET is designed to operate in digital fiber-optic systems running at data rates
up to 155 Mb/s. The pinFET reduces system engineering time by eliminating performance
matching between the detector, amplifier, and an automatic gain control loop while
maintaining stability.
Power Supply
Internal 0.01
碌f
power supply decoupling capacitors are used to improve
performance in noisy conditions. Additionally, external bypass capacitors with short leads
should be used at the supply pins. Capacitor values depend on system conditions. The
QDFB requires a single +5 and two -5 volt supplies, one for the detector and the other for
the amplifier. Pin 1 is dedicated to the detector and allows the photodiode current to be
monitored.
Output Loading Considerations
An output buffer enables the QDFB to drive
capacitive loads. Nevertheless, output loading should still be kept to a minimum; excessive
reactive loads can cause ringing and overshoot. Also, the output is generally AC-coupled
to the next stage to isolate post-amplification circuitry from shifts in pinFET dc output
voltage.
Maximum Overload Power
The maximum overload is defined as the input power
needed to cause a 1 volt peak-to-peak output voltage. Operation above this level is possible
because the QDFB does not start clipping until about 2.5 volts peak-to-peak, or at
approximately 0 dBm optical input power.
The sensitivity of every module is determined before shipment. The
sensitivity calculated is the input power needed to maintain better than 10
-9
Bit Error Rate.
The calculation is based on an RMS noise measurement under 鈥渘o light鈥?conditions.
Sensitivity
Manufacturing Information
The QDFB is subjected to a battery of processes including
active burn-in, temperature cycling, fine and gross leak test, and visual inspections.
All devices are tested before shipment; test results are included with each unit.
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2000
Corning Lasertron 2000 Product Guide
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