Query about ADL5530's Output

Hi, there

We are giving a PECL output from a ECL D-flip flop (MC100EP31) to ADL5530 (RF Amplifier). The amplitude of the input PECL signal is 700mV and the working voltage of RF amplifier in their design is 5V.

We were using the ADL5530 for improving the gain of the incoming signal whose amplitude is 700mV and pulse width is 1nS to 10nS

What we were seeing on the scope is a negative going signal whose amplitude is -2.5V and the pulse width exactly as the input.

We want to know whether this is the natural behavior of the chip. We are surprised to see that output.

By the way, we design following EVB schematic in the datasheet.

Thanks in advnce.

Br,

Wayne