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Thanks for your valuable reply.
My application is to read out the Hamamatsu Photo-Multiplier Tube Module output, the output is a TTL pulse with 20ns period, you can find the datasheet of the PMT below
https://www.hamamatsu.com/resources/pdf/etd/H10682_TPMO1075E.pdf
The PMT will capture some...
Hi Pros,
I need to count a TTL level high speed pulse train, rise time 1ns, fall time 1ns, pulse width 10ns, period 20ns.
I see that a lot of MCU input are not fast enough to capture such a high speed pulse, even some 24bit asynchronous counter, the parallel output is only the last 8bit, means...
Hi FvM, thanks for the reply.
Indeed, the transmission line topology is co-planar with ground, the RF trace in at outer layer. So you mean the ground via along the pour copper surrounding the RF trace is to avoid those pour copper become line stubs. I am not an RF expert so I don’t quite...
I am a PCB design engineer, the product from my company uses BLE solution, so there is a RF chip, followed by BAW filter and antenna.
Regarding the PCB design for this part of circuit, I have some questions that my wireless colleague can not explain to me clearly, I believe the good practice...
Hi guys, I know normally you design the noise trace pair(e.g Vdd and Vss) close to each other to reduce the magnetic coupling to other nets, but I do not understand what is the mathematical explanation of why this is helpful to reduce magnetic coupling.
One thing I can see is that the Vdd/Vss...
Thanks a lot for the detailed explanation, Klaus.
You are right, it should be a PMOS instead of NMOS, and I should choose an op amp cater to the input range(>3.8V) as well. After fixing the two issues, the positive and negative terminal is equal now.
I always have difficulty to judge whether...
I attached the circuit here, it use op amp negative feedback to control the charging current of the 3.8V battery by regulating current of R1.
And simulation result here
it seems that the opamp + and - terminal are not equal to each other, thus the circuit is not working, I wonder why.
Thank you for the reply, mayI know how do you estimate the 75um trace being able to handle 10dBm?
And if the trace is not 50ohm, but 30ohm or 70ohm, but length become shorter than 6mm, what will happen then?
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The PCB is flexi, total thickness is around 0.2mm, 4 layer, so...
The context is as follow:
My PCB thickness is very thin, and my PCB supplier gives me calculation of a microstrip impedance line for 50ohm, which resilts in a trace width of 75um, trace length about 20mm.
The trace is connecting output of RFIC PA to BAW filter, the application will use...
Hi Volker, I want to hear fro different opinions, I would admit I understand your explanation more then the other one, can you help to reply on my previous question? Thank you so much!
Hi Volker, thanks a lot for the explanation. So now I understand BAW's RX/TX and Antenna port is not designed to have 50 ohm impedance, thus needs external matching elements(caps and inductors) to achieve so. But if I say the signal line is less than 1cm, signal frequency is 2.4GHz, so we do not...
Hi, Thanks for the quick reply, what I mean by 50 ohm trace design is to design a 50 ohm characteristic impedance trace in the PCB for that rf signal, in which the PCB stack up, PCB trace width, and some other factors are considered.
Ok, refer to attached schematic I drew, I do not quite understand why the design is like this, I have below doubts:
1. are the caps and inductors for the purpose of impedance matching? If yes, is it still necessary to design the 50 ohm impedance trace at indicated location?
2. What is the...
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