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Yes it's true, but i'd say: voltage levels are almost identical like in Rs-422. I also noticed that you can be found both RS422 and RS232 on RJ45 connectors, of course the pinology is different. Although most often it is classic: RS422/RS485 on RJ45, and RS232 on D-Sub.
Hello.
I need to design circut between microcontroller and RJ45 connector which should contain PPS (Pulse Per Second), and ToD (Time of Day) signal outputs. I found defined pinout for PPS and ToD in ITU-T G.703, and voltage levels in T-REC-V.11 (recalled in G.703), but just for PPS signal...
Thanks Big Boss.
I made several dozen measurements and changes in two PCBs to diagnose the problem, and i don't meet strong distortions on U18 LNA output now, but i can't get this glitch back even by undoing the changes to the PCB, so I'm a bit lost, and i don't know what helped... So, now i...
What on the graph indicates that oscillations are occurring? I don't see S22/S11 going above 0 (unstability indicator), just one thing which looks "suspicious" is strong valley in S22 dB Mag chart, but is not on expected frequency, and had nothingh to say in oscillation thread (i think). I see...
This is partly how I started, but all I saw were some impedance mismatches in a few places, but I was measuring not individual components, but segments, for example 2 LNAs and a filter (what was between the UFLs), what was wrong i mean now.
I measured U18 using VNA. I left C160 and C80 because...
So, the first start of the radio (receive) path should look like this: I first perform measurements on each component (LNA, filter, splitter) separately using VNA (SA too?)? And only when these measurements show that the LNAs are stable and the impedance matching is quite good, can the track be...
BigBoss
1. You mean screening as coplanar wave, or EMC cage? PCB will be mounted in metal enclosure of course.
2. Transmision line microstrip is 4,9mil, when distance to reference plane is 2,95mil - i readed that exist rule that says the line width should be 2x distance to reference plane...
FvM
Yes, some peaks are from telephony, I have BTS in the area and Wi-Fi is also visible, but I still don't know why it gained too much.
BigBoss
S22 may be misleading as I have a 20 dB attenuator on the P2 VNA port and as I see it, adding an attenuator (included in the calibration) maximizes...
vfone
Thanks for information about noise figure. About -15dB return loss of this filter - my measurement (S22) doesn't look that bad in reference to datasheet. You thinkg bout layout near this filter - yes? I use VNA, but i have oscillosopce with FFT function, as You see on last graphics in...
Thanks for quick answer. Here i add piece of stackup, and impedance check for RF paths on TOP layer. It's look OK. Path has width 0,125mm. Unusal thin - You mean first (Dielectic1) prepreg thickness too thin? And example FL4 (filter) big pads are acting as real capacitors?
I measured S...
Much thanks for all. Connector via will be correced in next PCB revision. On this revision i can say, it work well enaught for now, but mismatch of course still exist.
Hi.
Im launching radio receiver for two bands. First RF path is common and containst two LNAs, next the path is splitted to two channels. Each channel starts with pass-band filter, and LNA TRF37D73 after him. First channel/band with center freq 1575MHz works well, i have about 8mVpp on LNA...
Thanks.
In this case it's possible to done impedance matching without editing SMA center pad hole?
Of course using CL, and LC matching networks like in this article: https://www.antenna-theory.com/tutorial/smith/smithchartC.php
However, will the problem with the middle SMA pad effectively block...
From curiosity, i added series resistor 39R to this path, and impedance moves closer to target, and i see about 5dB in low band, and 2dB in upper band power gain when I pass the signal from the generator to the SMA and measure it with a spectrum analyzer at the output of the LNA.
PS: sorry, i...
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