Selecting photodiode for Tranimpedance amplifier
in [Design]
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From: electro on 17 Jun 2010 09:11 I have a TIA with 1.5kohm of gain and 10GHz BW. I have to select a Photodiode for this TIA. I was wondering how do I determine the upper limit on photodiode junction capacitance when selecting the photodiode. Thank You --------------------------------------- Posted through http://www.Electronics-Related.com
From: MooseFET on 17 Jun 2010 09:23 On Jun 17, 9:11 pm, "electro" <khushalimn(a)n_o_s_p_a_m.gmail.com> wrote: > I have a TIA with 1.5kohm of gain and 10GHz BW. I have to select a > Photodiode for this TIA. I was wondering how do I determine the upper limit > on photodiode junction capacitance when selecting the photodiode. The feedback resistor and the capacitance form a low pass within the closed loop. The amplifier has an open loop response curve. Two things set the limit on capacitance. (1) The total gain around the loop must be greater than one at the desired system bandwidth. (2) The phase shift around the loop should not exceed 135 degrees at the point where the total gain is one.
From: George Herold on 17 Jun 2010 09:23 On Jun 17, 9:11 am, "electro" <khushalimn(a)n_o_s_p_a_m.gmail.com> wrote: > I have a TIA with 1.5kohm of gain and 10GHz BW. I have to select a > Photodiode for this TIA. I was wondering how do I determine the upper limit > on photodiode junction capacitance when selecting the photodiode. > > Thank You > > --------------------------------------- > Posted throughhttp://www.Electronics-Related.com As small as possible, Better yet hire Phil Hobbs as a consultant. George H.
From: John Larkin on 17 Jun 2010 09:46 On Thu, 17 Jun 2010 08:11:38 -0500, "electro" <khushalimn(a)n_o_s_p_a_m.gmail.com> wrote: >I have a TIA with 1.5kohm of gain and 10GHz BW. I have to select a >Photodiode for this TIA. I was wondering how do I determine the upper limit >on photodiode junction capacitance when selecting the photodiode. > >Thank You > You'll have a hard time connecting a discrete pin diode to a packaged tia, at least if you want 10 GHz bandwidth. This stuff is usually wire-bonded. It's easier to buy someone's packaged pin-tia in a can. The telecom parts are built in volume and are fairly cheap. John
From: Phil Hobbs on 17 Jun 2010 09:51
electro wrote: > I have a TIA with 1.5kohm of gain and 10GHz BW. I have to select a > Photodiode for this TIA. I was wondering how do I determine the upper limit > on photodiode junction capacitance when selecting the photodiode. > > Thank You > That sort of TIA isn't a general-purpose part--it will have been designed with specific photodiodes in mind, as well as specific construction techniques. I strongly suggest asking the manufacturer and listening closely to what they say--making a 10 GHz TIA work right is not something that happens by accident. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net |