Application of AD8015 in the photodiode receiver circuit

Question

I have made a LED transmitter circuit which can reach 100MHz, and I need a high speed receiver circuit, so I picked AD8015. The photodiode I used is SFH250V. 
 
 The receiver circuit I built is according to this figure, but I didn't add LPF, quantizer, clock recovery and the capaciors at 6 nd 7 pin. The test point is V1. The result is that the datarate of the receiver circuit is very slow only reach 9KHz. Also the amplitude of the received signal is small. C1=150pF, R=56 Ohm,Vs=8V.

So what caused it? Is there a better application solution?

ZoltanDTI · Accepted Answer

Hi Sebastian, 
 Your AD8015 seems to be saturated. The datasheet specifies output common mode voltage range minimum of +Vs-1.5V, so it is +3.5V. But the output on your scope screen photo shows output voltage somewhat below 0.4V. If you look at Figure 5. AD8015 Simplified Schematic in the datasheet, you can see that it is probably the saturation level of Q60. 
 This situation can easily occur, if the SFH250V is connected with reverse polarity. Then it conducts as a normal diode, large current flows through the 10k internal resistor of the amplifier and makes the output go down to the lowest possible level. 
 So check the polarity of the diode.

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Application of AD8015 in the photodiode receiver circuit

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