TZA3047B 데이터 시트보기 (PDF) - Philips Electronics
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TZA3047B Datasheet PDF : 28 Pages
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Philips Semiconductors
30 Mbits/s up to 1.25 Gbits/s laser drivers
Product specification
TZA3047A; TZA3047B
handbook, full pagewidth
VCCA
VCCD
DIN
DINQ
TEST
CIN
CINQ
GND
1 32 31 30 29 28 27 26 25
2
24 BIAS
3
23 GND
4
22 LA
5
TZA3047A
21 LA
TZA3047B
6
20 LAQ
7
19 LAQ
8
18 GND
9 10 11 12 13 14 15 16 17 PWA
MDB318
Fig.2 Pin configuration.
7 FUNCTIONAL DESCRIPTION
7.1 Data and clock input
The TZA3047 operates with differential Positive Emitter
Coupled Logic (PECL), Low Voltage Positive Emitter
Coupled Logic (LVPECL) and Current-Mode Logic (CML)
data and clock inputs with a voltage swing from 100 mV to
1 V (p-p). It is assumed that both the data and clock inputs
carry a complementary signal with the specified
peak-to-peak value (true differential excitation).
The circuit generates an internal common mode voltage
for AC-coupled data and clock inputs and for single-ended
applications.
If VDIN > VDINQ, the modulation current is sunk by the LA
pins and corresponds to an optical ‘one’ level of the laser.
7.2 Retiming
The retiming function synchronizes the data with the clock
to improve the jitter performance. The data latch switches
on the rising edge of the clock input. The retiming function
is disabled when both clock inputs are below 0.3 V.
At start-up the initial polarity of the laser is unknown before
the first rising edge of the clock input.
7.3 Pulse width adjustment
The on-duration of the laser current can be adjusted from
−100 to +100 ps. The adjustment time is set by resistor
RPWA. The maximum allowable capacitive load on pin
PWA is 100 pF. Pulse width adjustment is disabled when
pin PWA is short-circuited to ground.
7.4 Modulator output stage
The output stage is a high-speed bipolar differential pair
with typical rise and fall times of 120 ps and with a
modulation current source of up to 100 mA when the LA
pins are connected to VCCO.
The modulation current switches between the LA and LAQ
outputs. For a good RF performance the inactive branch
carries a small amount of the modulation current.
The LA output is optimized for the laser allowing a 2 V
dynamic range and a 1.2 V minimum voltage. The LAQ
output is optimized for the dummy load.
The output stage of the TZA3047A is optimized for
AC-coupled lasers and the output stage of the TZA3047B
is optimized for DC-coupled lasers.
The BIAS output is optimized for low voltage requirements
(0.4 V minimum for a 3.3 V laser supply; 0.8 V minimum
for a 5 V laser supply).
2003 Jun 05
7
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