On Sun, 18 Sep 2005, Vasile Surducan wrote: > On 9/18/05, Xiaofan Chen wrote: >> Yes in certain application we need a lot of gain and dynamic range. > > Yes, then if we are poor and don't want to waste our money on > expensive OA we split the necessary gain on the amplifier chain. Keep > the current to voltage conversion in a convenient low gain (this will > keep the fast transient response) and use two supplementary OA for > increasing the overall gain. I'm affraid this is the way for a 60dB > gain, right ? > Fortunately low input current OA accept feedback values of up to 100M > or more if are used corectly. Why not set up a cascode amplifier with the diode as the 'first' stage and see what happens ? With a switching transistor as the 'next' stage it should follow light input into the 10's of MHz at least. Peter -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist