I'm trying to design a high speed drive circuit and I want to gain high output current(hundreds mA). I tried to make the output stage transistor big, but it is not easy to get it? Can anyone help me with this?
hi,
You can get high drive capability by increasing the size of the transistor.
But instead of increasing the size of the transistor in one step, try to increase the size in many steps(stages).
Try to use bipolar transistors for differential pairs if you are using BiCMOS process. It gives better drivability and faster speed. Make sure your output impedance is small, or you may parallel ferite inductor (off chip) to the load to avoid large headroom drop due to large DC current.
I believe large transistor size or lots of multiple transistors is unavoidable.