Other Parts Discussed in Thread: TINA-TI
I am having trouble using the THS4520 as an MFB differential high-pass filter. I am trying to use the device to stack the same active-filter for hard roll-off, schematic below.
I am finding that a single stage functions as expected when isolated from the 2nd stage. However, as soon as I populate C10 and C11 on my board the circuit becomes unstable. An oscillating signal of fixed amplitude, in the range of 120MHz to 140MHz appears at both complementary outputs of the first stage. This is then amplified by the second stage and so on…
Any ideas what could be causing the instability and how to solve it?