Philips TZA3046 User Manual
TZA3046
Fiber Channel/Gigabit Ethernet transimpedance amplifier
Rev. 01 — 19 May 2006 Product data sheet
1. General description
The TZA3046 is a transimpedance amplifier with AutomaticGainControl(AGC), designed
to be used in Fiber Channel/Gigabit Ethernet (FC/GE) fiber optic links. It amplifies the
current generated by a photo detector (PIN diode or avalanche photodiode) and converts
it to a differential output voltage. It offers a current mirror of average photo current for
RSSI monitoring to be used in SFF-8472 compliant modules.
The low noise characteristics makes it suitable for FC/GE applications, but also for
FTTx applications.
CAUTION
This device is sensitive to ElectroStatic Discharge (ESD). Therefore care should be taken
during transport and handling.
2. Features
n Low equivalent input noise current, typically 126 nA (RMS)
n Wide dynamic range, typically 2.5 µA to 1.7 mA (p-p)
n Differential transimpedance of 7.5 kΩ (typical)
n Bandwidth from DC to 1050 MHz (typical)
n Differential outputs
n On-chip AGC with possibility of external control
n Single supply voltage 3.3 V, range 2.97 V to 3.6 V
n Bias voltage for PIN diode
n On-chip current mirror of average photo current for RSSI monitoring
n Identical ports available on both sides of die for easy bond layout and RF polarity
3. Applications
n Digital fiber optic receiver modules in telecommunications transmission systems, in
selection
high-speed data networks or in FTTx systems.
Philips Semiconductors
4. Ordering information
Table 1: Ordering information
Type number Package
TZA3046U - bare die, dimensions approximately
5. Block diagram
TZA3046
Fiber Channel/Gigabit Ethernet transimpedance amplifier
Name Description Version
-
0.82 mm × 1.3 mm
I
IDREF_MON
R
IDREF_MON
C
DREF
Fig 1. Block diagram
C
VCC
IDREF_MON
DREF
D
PHOTO
I
PIN
IPHOTO
0.2 × I
5 or 16
1 or 3
2
DREF
low noise
amplifier
R
DREF
GAIN
CONTROL
V
4 or 17
I
DREF
290 Ω
AGC
CC
6 or 15
PEAK DETECTOR
single-ended to
differential converter
9, 10, 11, 12
GND
BIASING
buffers
output
TZA3046
7 or 13
8 or 14
OUTQ
OUT
001aae511
TZA3046_1 © Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Product data sheet Rev. 01 — 19 May 2006 2 of 15
Philips Semiconductors
6. Pinning information
6.1 Pinning
TZA3046
Fiber Channel/Gigabit Ethernet transimpedance amplifier
DREF
IPHOTO
DREF
1
2
V
174
CC
IDREF_MON
165
AGC
156
OUT
14
OUTQ
13
129
GND
1110
GND
001aae512
V
CC
IDREF_MON
AGC
OUTQ
OUT
GND
GND
3
TZA3046
7
8
Fig 2. Pin configuration
6.2 Pin description
Table 2: Bonding pad description
Bonding pad locations with respect to the center of the die (see Figure 10); X and Y are inµm.
Symbol Pad X Y Type Description
DREF 1 −493.6 140 output bias voltage output for PIN diode; connect cathode of PIN diode to
pad 1 or pad 3
IPHOTO 2 −493.6 0 input current input; anode of PIN diode should be connected to this pad
DREF 3 −493.6 −140 output bias voltage output for PIN diode; connect cathode of PIN diode to
pad 1 or pad 3
V
CC
IDREF_MON 5 −213.6 −278.6 output current output for RSSI measurements; connect a resistor to pad 5
AGC 6 −73.6 −278.6 input AGC voltage; use pad 6 or pad 15
OUTQ 7 66.4 −278.6 output data output; complement of pad OUT; use pad 7 or pad 13
OUT 8 206.4 −278.6 output data output; use pad 8 or pad 14
GND 9 346.4 −278.6 ground ground; connect together pads 9, 10, 11 and pad 12 as many as
GND 10 486.4 −278.6 ground ground; connect together pads 9, 10, 11 and pad 12 as many as
4 −353.6 −278.6 supply supply voltage; connect supply voltage to pad 4 or pad 17
or pad 16 and ground
[1]
possible
possible
TZA3046_1 © Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Product data sheet Rev. 01 — 19 May 2006 3 of 15
Philips Semiconductors
TZA3046
Fiber Channel/Gigabit Ethernet transimpedance amplifier
Table 2: Bonding pad description
Bonding pad locations with respect to the center of the die (see Figure 10); X and Y are inµm.
Symbol Pad X Y Type Description
GND 11 486.4 278.6 ground ground; connect together pads 9, 10, 11 and pad 12 as many as
GND 12 346.4 278.6 ground ground; connect together pads 9, 10, 11 and pad 12 as many as
OUTQ 13 206.4 278.6 output data output; complement of pad OUT; use pad 7 or pad 13
OUT 14 66.4 278.6 output data output; use pad 8 or pad 14
AGC 15 −73.6 278.6 input AGC voltage; use pad 6 or pad 15
IDREF_MON 16 −213.6 278.6 output current output for RSSI measurements; connect a resistor to pad 5
V
CC
[1] These pads go HIGH when current flows into pad IPHOTO.
17 −353.6 278.6 supply supply voltage; connect supply voltage to pad 4 or pad 17
…continued
possible
possible
[1]
or pad 16 and ground
7. Functional description
The TZA3046 is a TransImpedance Amplifier (TIA) intended for use in fiber optic receivers
for signal recovery in FC/GE or FTTx applications. It amplifies the current generated by a
photo detector (PIN diode or avalanche photodiode) and converts it to a differentialoutput
voltage.
The most important characteristics of the TZA3046 are high receiver sensitivity, wide
dynamic range and large bandwidth. Excellent receiver sensitivity is achieved by
minimizing transimpedance amplifier noise.
The TZA3046 has a wide dynamic range to handle the signal current generated by the
PIN diode which can vary from 2.5 µA to 1.7 mA (p-p). This is implemented by an AGC
loop which reduces the preamplifier feedback resistance so that the amplifier remains
linear over the whole input range. The AGC loop hold capacitor is integrated on-chip, so
an external capacitor is not required.
The bandwidth of TZA3046 is optimized for FC/GE application. It works from DC onward
due to the absence of offset control loops. Therefore the amount of Consecutive Identical
Digits (CID) will not effect the output waveform. A differential amplifier converts the output
of the preamplifier to a differential voltage.
7.1 PIN diode connections
The performance of an optical receiver is largely determined by the combined effect of the
transimpedance amplifier and the PIN diode. In particular, the method used to connect the
PIN diode to the input (pad IPHOTO) and the layout around the input pad strongly
influences the main parameters of a transimpedance amplifier, such as sensitivity,
bandwidth, and PSRR.
Sensitivity is most affected by the value of the total capacitance at the input pad.
Therefore,to obtain the highest possible sensitivity the total capacitance should be as low
as possible.
TZA3046_1 © Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Product data sheet Rev. 01 — 19 May 2006 4 of 15
Philips Semiconductors
The parasitic capacitance can be minimized through:
1. Reducing the capacitance of the PIN diode. This is achieved by proper choice of PIN
diode and typically a high reverse voltage.
2. Reducing the parasitics around the input pad. This is achieved by placing the PIN
diode as close as possible to the TIA.
The PIN diode can be biased with a positive or a negative voltage.Figure 3 shows the PIN
diode biased positively, using the on-chip bias pad DREF. The voltage at DREF is derived
from VCCby a low-pass filter comprising internal resistor R
which decouples any supply voltage noise. The value of external capacitor C2 affects the
value of PSRR and should have a minimum value of 470 pF. Increasing this value
improves the value of PSRR. The current through R
IDREF_MON, see Section 7.3.
If the biasing for the PIN diode is done external to the IC, pad DREF can be left
unconnected. If a negative bias voltage is used, the configuration shown in Figure 4 can
be used. In this configuration, the direction of the signal current is reversed to that shown
in Figure 3. It is essential that in these applications, the PIN diode bias voltage is filtered to
achieve the best sensitivity.
TZA3046
Fiber Channel/Gigabit Ethernet transimpedance amplifier
and external capacitor C2
DREF
is measured and sourced at pad
DREF
For maximum freedom on bonding location, 2 outputs are available for DREF (pads 1
and 3). These are internally connected. Both outputs can be used if necessary. If only one
is used, the other can be left open.
V
R
DREF
290 Ω
TZA3046
CC
4 or 17
001aae514
V
CC
4 or 17
R
DREF
1 or 3
DREF
C2
470 pF
I
PIN
IPHOTO
290 Ω
2
TZA3046
001aae513
Fig 3. The PIN diode connected between
the input and pad DREF
1 or 3
DREF
IPHOTO
negative
bias voltage
2
I
PIN
Fig 4. The PIN diode connected between
the input and a negative supply
voltage
TZA3046_1 © Koninklijke Philips Electronics N.V. 2006. All rights reserved.
Product data sheet Rev. 01 — 19 May 2006 5 of 15
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