Good Morning,
I am writing because I have had a problem with the HMC862A divider used as a prescaler for a PLO, where I am trying to obtain division in a bandwidth of 10-20 GHz.
At first glance, looking at the divider without any other components or path, just turn it on. A small oscillation is visible when no RF is applied, which disappears when RF is applied.
I have ensured that the supply voltage precedes the control signals, the input is single ended with 100 nF capacitors attached to the component, and I would not consider the RF path to be long. The output was previously configured as differential, but when testing the divider to study its behaviour, it was set to single-ended output, where the 100 nF capacitors are also attached and the negated-OUT signal ends with 50 Ohm resistance. It is also currently configured with an N=8.
While conducting tests, I noticed that the splitter was not performing well above 16 GHz, even though I had completely isolated it from the board and used a generator to sweep the 10-16 GHz frequency range to see its effect and ensure that it was receiving the maximum power it could handle (+10 dBm). But as soon as it reached 16 GHz, it stopped performing the division and only noise was visible on the analyser. I tried replacing it with a new one in case it had broken. With the new one isolated from all the components on the PCB (I bypassed the input path to the splitter and connected an external cable to feed the generator signal directly into it, as I did with the one that reached 16 GHz, and did the same with the output, but feeding it into the analyser), I increased the splitting range to 18 GHz, but it still did not reach the maximum that, according to the technical data sheet, it can reach.
I tried reducing the power, and the effect was that the frequency at which it was able to perform the division was getting lower and lower. I also tried changing the input capacitors to 1pF to see if it would perform better at high frequencies, but I didn't notice any improvement. I changed the division to N=4, but the same effect continues.
I am attaching a video in which you can see how, with a power of 5 dBm in the generator (with cable losses it will be less), before 18 GHz the division is lost, and then by increasing the power it is possible to reach 18 GHz, but there comes a point where even at maximum power the divider cannot perform the division above 18 GHz. Furthermore, when it is at frequencies such as 17.9 or 17.8 GHz for a while, it must be so close to the limit that the division ends up disappearing, and you have to stop feeding the component and wait a while for it to reach 18 GHz for a few moments.
Any idea why it can't divide beyond 18 GHz? Any possible solutions to the problem? Or Is there any possible replacement for the HMC862A?
Thank you very much.
