Hi,
We are developing a chip which we expect to replace some commercial ones. The commercial one is Bicmos in which the output is PECL buffer. We use the CMOS process to replace it, so we can only use it with CML output buffer. If the applications is AC coupling, I think it is OK for the CML-PECL connection. But if the applications need DC coupling, we know it is difficult for the CML-PECL connection considering the decrepancy of the two buffers.

Can I implement the PECL with two external bipolar transistors, i.e., on chip CML buffer+external bipolar transistors to implement the PECL output? Is any price, performance, etc.. concerns for the customers?

Thanks in advance for the comments