QDFT Series
High-Sensitivity Transimpedance
pinFET Receiver
I
I
I
I
Fixed transimpedance circuit configuration
Hybrid construction
Industry-standard 14-pin dual-in-line package
Multimode fiber
Description
The Corning Lasertron QDFT pinFET module is a high-sensitivity detector and hybrid
preamplifier module designed for fiber-optic receivers operating at data rates up to and
exceeding 420 Mb/s at 1300 and 1550 nm wavelengths. The transimpedance circuitry
provides excellent sensitivity and superior dynamic range. The high sensitivity results from
use of an advanced GaInAs detector element having <10 nA leakage and a responsivity of
>0.8 A/W at 1300 and 1550 nm.
Sensitivities range from -53 dBm at 18 Mb/s, to -43 dBm at 140 Mb/s. Optical dynamic
range exceeds 25 dB. Operation requires only +5 V power supplies at modest bias currents.
The QDFT is packaged in a hermetically sealed, low-profile, 14-pin DIL package and is
pigtailed with multimode fiber.
Applications
The Corning Lasertron QDFT pinFET module consists of a low-capacitance,
front-illuminated planar detector element followed by a hybrid transimpedance amplifier.
Benefits of the transimpedance design of the QDFT pinFET module include excellent
dynamic range and ease of implementation. The QDFT pinFET requires no equalization
and is self-biasing. Simply by applying +5 V and -5 V supplies to the amplifier circuit, and
a -5 V supply to the detector element, the device is ready to receive an optical input through
a multimode fiber-optic pigtail.
The diagram to the left illustrates the fundamental operation of a QDFT pinFET. As
incident light illuminates the detector, a small signal current is produced which is directly
proportional to the amplitude of the incident light source (P
i
) and the responsivity (R) of
the detector.
This simple relationship of R 鈥?P
i
yields the output signal current (I
s
). This current is
then converted to a voltage with the transimpedance resistor (Z
t
) and a gain block amplifier.
The resulting signal voltage (V
s
) is simply derived from the quantities I
s
鈥?Z
t
.
TRANSIMPEDANCE DESIGN CIRCUITRY
Pin Connections
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Detector Bias (-5 V)
NC
Case Ground
-5 V
Case Ground
NC
Output
Case Ground
NC
+5 V
NC
NC
NC
NC
(Bias and interface circuit)
Specifications and Ordering Information
38
2000
QDFT Low-Bandwidth pinFET Receiver, page 39
QDFT Moderate-Bandwidth pinFET Receiver, page 40
QDFT High-Bandwidth pinFET Receiver, page 41
Corning Lasertron 2000 Product Guide
1
2
3
4
