Total Power Consumed by an Entire Opto-electronic Link

1
Total Power Consumed by an Entire Opto-electronic
Link

2
The total power consumed by an entire
opto-electronic link is given by
For zero length link
Power required by photodiode
Power required by laser driver.
Power required by laser
Power required by TransImpedance Amplifier for
converting photocurrent to voltage
Power required by Clock and Data Recovery
circuitry
3
PDriver
According to various references we have
Dominated by the capacitance of the laser, about
10 pF.
Bit/second
VddTypical 3.3 V
Switching factor duty cycle of the link
(modulation and activity dependant)
4
PVCSEL
Steady state power dissipation of a VCSEL
(vertical cavity laser or conventional diode
laser).
About 1.8 V
?6 mA for VCSEL ? 50 mA for conventional Laser
diode (LD)
? 0.7V
About 0.2 V
? 20 mA for VCSEL ? 80 mA for LD
5
Pphotodiode
The photodiode requires a bias voltage and the
associated power is negligible respect to TIA
power. APDs require high voltage sources that are
not energetically negligible Typical power
required by APD bias circuitry is 10 mW
(activation time hundreds ms) see datasheet of
LT3482.
P TIA
Dark current 40 nA
About 15 V
Output capacitance of amplifier,
about 1 pF
Amplifier gain at DC and in band about 5000
3.3 V
Output voltage swing (3V)
About photodiode capacitance (1 pF)
?2?Bitrate
6
PCDR
Capacitance of the clock and data recovery unit.
About 1 pF