COTS 20 GHz PLL options - Page 1
Forum section: electronics / rf-microwave

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: January 07, 2021, 09:09:16 am
content: For a product we need a 10-20 GHz COTS PLL. Currently it seems like Analog and TI are the only two vendors that provide such a device. Are there any other vendors that provide a PLL that can provide a 10-20 GHz PLL? Preferably not in the USA?

author: rf-messkopf
author_rank: Regular Contributor
timestamp: January 08, 2021, 01:16:48 am
content: Quote from: TheUnnamedNewbie on January 07, 2021, 09:09:16 amDo you mean a synthesizer chip with integrated VCO, fractional dividers and phase-frequency detector? I don't think there are too many integrated PLL synthesizers that work up to 20 GHz.What comes to mind is the STuW81300 from ST. That's an integrated fractional N synthesizer with one output ranging from 1.925 to 8.0 GHz, and another one from 7.7 to 16.0 GHz. In your application you would need an external doubler and do switching between the two outputs.Another option would be 8V97003 from Renesas, which works from 171.875 MHz to 18 GHz (you'd also need an external doubler).There should be more options if you don't go for an integrated solution. For example, the MAX2880 fractional N PLL from Maxim could be used with an external VCO and a div-by-2 prescaler in front of the RF input.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: January 08, 2021, 09:39:56 am
content: Quote from: rf-messkopf on January 08, 2021, 01:16:48 amYes, that is what I'm looking for.Quote from: rf-messkopf on January 08, 2021, 01:16:48 amThanks for these suggestions. I really do need a fully integrated option, I don't think we have room on our boards to add switches and multipliers (as is, we will probably already need two of these synth chips). We might be able to add another multiplier in our ASIC instead.

author: Gerhard_dk4xp
author_rank: Frequent Contributor
timestamp: January 09, 2021, 03:14:59 am
content: That the synthesizer chip has the doubler built-in does not meanyou're done with it. In the ADF5356, the fundamental is nearly asstrong as the doubled output.I had some doubts about a register value and opened a thread in the engineer zone.Since I was at it, I added a picture of the 10 GHz wave:<https://ez.analog.com/rf/f/q-a/536893/adf5356-doubts-about-bleeding-current-programming>So you may have to filter out the fundamental. For an output of 10 to 20 GHz thatprobably requires band switching. I would not assume that the faster chips are better.BTW this simple structure makes a good 6 GHz fundamental killer (35 dB):<https://www.flickr.com/photos/137684711@N07/50404949846/in/datetaken/>6.6/3.3 GHz fundamental, self-etched on Rogers TMM6, 0.65mm, eps-r=6, 14mm diaThe 90° wave extinguishes the 270° wave. I peeled some copper away to see if thathad any influence. It did not.cheers, Gerhard

author: KE5FX
author_rank: Super Contributor
timestamp: January 09, 2021, 04:12:47 am
content: Quote from: rf-messkopf on January 08, 2021, 01:16:48 amThat's an interesting part. I've been really impressed with the LMX2820 after trying it out recently, and this one is cheaper with similar performance.Distributor inventory levels on both are scary, but that's true of a lot of parts these days...

author: Aiy
author_rank: Regular Contributor
timestamp: January 10, 2021, 02:23:07 pm
content: Another tip is the LMX2595. I have good experience with this part. Similar in construction to the LMX2820 but with different fundamental VCO frequencies. As mentioned by Gerhard the doubler will still let the fundamental through at some level, so you might need external filters. If you partner it with say an HMC451 (single +5V/114mA) as output amplifier you have good output drive as well. Note that the built-in attenuator does have some range but you're not getting 0.1dB stepping.Best regards

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: January 11, 2021, 08:42:38 am
content: Quote from: Gerhard_dk4xp on January 09, 2021, 03:14:59 amPutting a resonant filter to kill the 10 GHz tone on PCB would not be an option for us, this would be way to large. However, we might be able to get away with it with our on-chip matching networks.thanks for the pointer though, good to know that this is a potential issue, we will have to take that into account in our baseband design.Quote from: Aiy on January 10, 2021, 02:23:07 pmThanks for the tip, but this is again a TI part. Ideally we need a non-US company for design partner reasons.