Need feedback on PCB design for distribution amplifier - Page 1
Forum section: electronics / rf-microwave

author: Filip SP9GMD
author_rank: Newbie
timestamp: September 15, 2024, 03:25:05 pm
content: Hi,I need your feedback on the PCB design.Background:Together with Jie Feng (9V1BG), we designed a GPSDO and a distribution amplifier for it. This amplifier is intended for a 10MHz frequency. Our project will become open source, and everyone will be able to order assembled boards from JLCPCB at the lowest price possible.I'm going to add vias stitching after implementing changes proposed by you.I haveneverdesigned a PCB for RF applications; I have only breadboarded my circuits. That's why I'm asking for help. Any ideas for improvement would be appreciated!Filip SP9GMD

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: September 15, 2024, 05:39:12 pm
content: Your board appears to be under 50 x 50 mm, so you can make it 4 layers for no extra cost at all.If you use 4 layers it'll make routing much easier, and you won't have to cut up your ground plane.

author: Filip SP9GMD
author_rank: Newbie
timestamp: September 16, 2024, 06:48:56 am
content: Thank you, I will use two outside signal layer, one internal groundplane and internal power layer.What else could be improved?What do you think about those traces around SMA outputs on the right? I mean those squares made from traces connecting floating ground. Is it beneficial?

author: jonpaul
author_rank: Super Contributor
timestamp: September 16, 2024, 02:47:46 pm
content: Bonjour: We use the excellent Leo Bodnar GPDSOs without ANY such complex gadget.Just set output at MAX 32 mA and add a passive Mini-Circuits splitter as needed, perhaps $10 each, to drive directly 4..10 instruments.Have no idea who is your partner, Jie Feng perhaps designed this?Its Premature to comment on fixing the PCB as the concept, circuit and BOM need to be fixed up.As you do not give any info on the specs, min/max levels, etc we cannot give a detail critique.shortly: No LC filter needed on input.Poor choice of amps and transfor,mersSchematic needs vomplete revTry "Time Nuts" forums on clock buffers/master amplifiers, CMRR/noise effect on phase stability, etc.Cheers!Jon

author: Filip SP9GMD
author_rank: Newbie
timestamp: September 16, 2024, 06:45:05 pm
content: Hi,This circuit should accept signal from Si5351.I want to archive high signal level, because some of USSR-made equipment requires about 6Vpp minimum at the input.Can you elaborate why this op amp and transformers are poor choice?Thank you for recommending me "Time Nuts"!I don't understand this line: "Have no idea who is your partner, Jie Feng perhaps designed this?" What did you mean?

author: jonpaul
author_rank: Super Contributor
timestamp: September 17, 2024, 05:18:12 am
content: Hello: Poor choice of source., Si5351 is not for a precision clk ref.suggest GPSDSO like Leo BodnarEven Skywork has a low jitter part.https://www.skyworksinc.com/Products/Timing/Ultra-Low-Jitter-Clock-GeneratorsWe work only with USA or EU made professional quality instruments, all have a 5 or 10 MHz 50 Ohm input that easily accepts 50...500 mV RMS REF .No idea about old USSR or Russian/ Iron Curtain instrumentsI have seen Commi radios and scopes copied from Western models , very low quality monsters.Just get better instruments in the lab.Have an absoluteluy fantatstic dayJon

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: September 17, 2024, 07:06:35 am
content: Is the input to the instrument 50 ohms? At 3V amplitude that's almost 100mW of power. Seems very high for a test instrument.