I aimed to use a ramp signal to manually sweep Vtune of ADF4350. I created the ramp within 0.5~2.7v with LM555 counter (with frequency of 120kHz). Then, I connected the port 6 of LM555 (output) to Vtune of ADF4350. Unfortunately, after connecting, the ramp was totally disrupted. i cannot use a capacitor as a coupling devise; because as you know, we need the DC level. Could you please inform me why this circumstance occurs?
Moreover, do you have any suggestion for implementing a sweeper with ADF4350? we cannot program ADF; because we need a high sweep rate which cannot be achieved due to lock delay of ADF.
I am awaiting your response and any comments and suggestions.