This is a rookie question, but I'm quite confused about the ECL termination used on the ADCMP565 evaluation board
First, in the IC datasheet, they show how to terminate the ECL outputs to drive 50Ω recievers.
The schematic they show is similar to what is shown in this application note, which is a series termination that assumes unterminated, high-impedance receiver inputs.
In the evaluation board schematic, you can see the termination at pins 2 and 3 for example, which uses different values for the resistors and the termination voltage in addition to using caps.
My questions are:
- Why does the datasheet mention 50Ω receivers while the application note says that this termination is useful for high impedance receivers?
- What is the difference between the termination shown in the ADCMP565 datasheet vs that shown in that of the evaluation board?
- What are the caps in the eval board termination useful for?