A square-wave of 92kHz will be created with LTC1668. the circuit is shown below.
Its CLK pin and I/O pins are connected with a FPGA chip. Its clock is 20MHz. The input to I/O is switched between oxFFFF and ox0000 with 92kHz..
The signal between A (or B) and AGND meet expectation, such as
BUT, the signal bwteen A and B (differential output) DON'T like a square-wave, just like
What is the reason? How to get a good square wave?