Hi, I am working with a photodiode optimized to have a bandwith higer then
5 GHz on a 50 ohm load. 1dB saturation current is arond 40mA. The best bias circuit for such a kind of diode would be a low noise DC voltage source that can keep the voltage fixed at 9V -10V even if current is varying from 0 to 40mA in 50ps-100ps. What would you suggest to design such a DC source ?
How about a 10 volt linear regulator with some bypass caps on the output?
John
Are you sure you need 40mA? You may be making your task more difficult than it need be.
I would expect a InGaAs diode with 1dBm input to have a photo-current of about 1mA. An avalanche diode would have a higher photo-current but it would need a higher voltage and you wouldn't need to use one with
1dBm of input available.kevin
On 20 Nov 2005 11:52:20 -0800, "deep78" wroth:
In the good old days, a mercury battery (or a string of them) was/were the bias supply of choice for stability and low noise. Even today, no solid-state supply can match a battery for low noise characteristics. Plus, a battery can be floated with gigohms of isolation.
Jim
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