tza3043b NXP Semiconductors, tza3043b Datasheet - Page 5

• Manufacturer Part Number: tza3043b
• Description: Gigabit Ethernet/fibre Channel Transimpedance Amplifier
• Manufacturer: NXP Semiconductors

Philips Semiconductors
FUNCTIONAL DESCRIPTION
The TZA3043 is a transimpedance amplifier intended for
use in fibre optic links for signal recovery in Fibre Channel
or Gigabit Ethernet applications. It amplifies the current
generated by a photo detector (PIN diode or avalanche
photodiode) and transforms it into a differential output
voltage. The most important characteristics of the
TZA3043 are high receiver sensitivity and wide dynamic
range. High receiver sensitivity is achieved by minimizing
noise in the transimpedance amplifier.
Input circuit
The signal current generated by a PIN diode can vary
between 2.5 A to 1.5 mA (p-p).
An AGC loop is implemented to make it possible to handle
such a wide dynamic range. The AGC loop increases the
dynamic range of the receiver by reducing the feedback
resistance of the preamplifier.
2000 Mar 28
handbook, full pagewidth
handbook, full pagewidth
Gigabit Ethernet/Fibre Channel
transimpedance amplifier
Fig.6 Logic level symbol definitions for data outputs OUT and OUTQ.
V CC
V O(max)
V O(min)
V OQH
V OQL
V OH
V OL
Fig.5 Differential data output circuit.
800
2 mA
800
5
V OO
The AGC loop hold capacitor is integrated on-chip, so an
external capacitor is not needed for AGC.
AGC monitoring
The AGC voltage can be monitored at pad 13 on the bare
die (TZA3043U/TZA3043BU). Pad 13 is not bonded in the
packaged device (TZA3043T/TZA3043BT). This pad can
be left unconnected during normal operation. It can also be
used to force an external AGC voltage. If pad 13 (AGC) is
connected to GND, the internal AGC loop is disabled and
the receiver gain is at a maximum. The maximum input
current is then approximately 75 A.
Output circuit
A differential amplifier converts the output of the
preamplifier to a differential voltage (see Fig.5).
The logic level symbol definitions for the differential
outputs are shown in Fig.6.
4.5 mA
4.5 mA
30
30
MGR290
MGR243
V CC
V o(p-p)
OUTQ
OUT
TZA3043; TZA3043B
Product specification