Hi Rajesh,

a schematic would help. However, I've run into a similar problem before and i guess you're talking about the same thing. Start-up can be achieved using just a pair of start-up transistors (pretty easy to design), or you can just add a high impedance load (current source) to the stage which is driving the TIA.

cheers,
Aaron

Hi,


your output current sources are pulling the output CM low at start-up. This is fed back to the input diff pair so that it cannot turn on. I'm not sure how well it would work, but you could try this:

Use a pair of PMOS with their drain source accross the gate source of the input diff pair, and the PMOS gates connected to the outputs. So when the output is low, the PMOS will turn on and pull the gates of the input diff pairs up. This will pull the output up and turn off the PMOS start-up transistors.

Like i said, i'm not so sure how well it would work, but as far as i know, when you have a self-biased circuit like that, you need some kind of start-up...


Sorry i took so long to reply,
Aaron