[SOLVED] Photodiode daylight filter

[chippevijaya]

Dear friends,
I am developing a IR Laser receiver. for that i have chosen QSD2030F photo-diode(Peak sensitivity λ = 880nm), from fairchild, And i have connected this to a high speed transimpedance amplifier.

Here the problem comes in picture, whenever i have taken this module to outdoor environment, under sunlight, there is a dc-offset and it is completely high(up to 5VDC, entire is working on 5V). So i am unable capture the pulses of laser that fired on it. the QSD2030F is showing having daylight filter option, but it is not working under daylight.

In indoor condition the DC-offset is as low as, i can capture the pulses.

Is there any idea that to eliminate the daylight effects, and my module will work under sunlight.

Please help me...

regards
vijay

 

[FvM]

I/V converters (transimpedance amplifiers) can be designed for different DC current levels. An obvious consideration is to modify the circuit in this respect.

Daylight or ultimately small bandwidth interference filters can be helpful, nevertheless. Photodiodes are availble with built-in daylight filter (black plastic case), but it will still pass IR components of sunlight and incandescent lamps. Interfernce filters are more effective but expensive.

 

[chippevijaya]

I/V converters (transimpedance amplifiers) can be designed for different DC current levels. An obvious consideration is to modify the circuit in this respect.

Daylight or ultimately small bandwidth interference filters can be helpful, nevertheless. Photodiodes are available with built-in daylight filter (black plastic case), but it will still pass IR components of sunlight and incandescent lamps. Interference filters are more effective but expensive.

Thank you for your reply,
Will you suggest any amplifier for amplification instead of transimpedance.
Your are right, these built-in daylight filtered QSD2030F diode still passing IR components in incandescent lamps also. But we are using TSOP34156 in another case with 56KHz modulation, even though it is accepting sunlight due to modulation it is responding to only modulated data.
But right now in present application we are sending only pulses, without modulation.

Please reply me.....

 

[FvM]

Yes, remote control receiver ICs are an example of devices that are designed with sufficient ambient good tolerance. It involves an input amplifier stage that isn't saturated by DC current.

I don't suggest a particularly circuit. You can use transimpedance, but the gain has to be limited according to expectable DC current. Further signal amplification can be applied after AC coupling/high-pass.