BarsMonster

Moscow, Russia

3.14.by

Age: 34

Software developer (in love with C++). Hardware geek (FPGA's, STM32, AVR, crazy stuff from discrete components), love LED indicators (7-segment, alphanumeric). Trying to understand ASIC design & manufacturing better at the moment. Also, trying to wrap my head around lens design, but that is not going to be that easy.

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2d
awarded Famous Question
Jan
25
asked Quantim efficiency of a radio receiver
Jan
14
awarded Yearling
Jan
11
awarded Notable Question
Jan
11
awarded Popular Question
Dec
24
awarded Favorite Question
Dec
23
awarded Nice Answer
Dec
19
awarded Tumbleweed
Dec
15
accepted SiGe/GaAs RF MMIC as photodiode preamp
Dec
12
asked Set 120 or 144hz refrash rate in VmWare Kubuntu 15.10 guest
Dec
9
comment SiGe/GaAs RF MMIC as photodiode preamp
There are indeed cheap APD on ebay, but they are for laser rangefinders, and sense area is quite small... 25-100mm2 photodioes are much more accessible...
Dec
9
comment SiGe/GaAs RF MMIC as photodiode preamp
50ohm at 5pf gives around 0.5ns risetime and ~600Mhz cutoff frequency... So we can get ~10x improvement by using ~1Ghz amp? When looking at this from another side: given that photodiode+amp capacitance is 5pf, 1 photon will give us 3.2*10^-8 V peak voltage which is quite a bit closer to the detection limit. This peak voltage will then decrease according to RC impulse response.
Nov
29
comment SiGe/GaAs RF MMIC as photodiode preamp
I see... Your formula literally asks to use faster amp, right where 50 Ohm termination with intrinsic diode+amp capacitance will give matching RC constant :-)
Nov
29
comment SiGe/GaAs RF MMIC as photodiode preamp
@BrianDrummond 10pF capacitance with 50 Ohm gets us around 0.5ns RC constant... So if we bump up the frequency to 1-2-4Ghz we should be fine with 50 Ohm?
Nov
29
comment SiGe/GaAs RF MMIC as photodiode preamp
@Andyaka Added links to the parts.
Nov
29
revised SiGe/GaAs RF MMIC as photodiode preamp
added 181 characters in body
Nov
29
asked SiGe/GaAs RF MMIC as photodiode preamp
Nov
19
awarded Popular Question
Nov
7
accepted Best approach for designing 40A laser diode driver?
Oct
25
awarded Nice Question
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