The characteristic-impedance tag has no wiki summary.
4
votes
2answers
152 views
Why Characteristic Impedance must be “50” ohms?
Where does this number came from?
For single ended it must be 50 ohm and for differential pairs 100 ohm. Why?
For PCB with controlled-impedance these are that common numbers. Outside of the PCB you ...
10
votes
1answer
206 views
GPS Design Review (RF Input)
I've designed a PCB in Eagle to host a GPS Receiver module and a GPS patch antenna. The RF input to the module is specified as a 50Ω unbalanced (coaxial) RF input. I used this calculator to calculate ...
16
votes
3answers
332 views
Transmission line reflection. I would like a non-mathematical explanation
I am a licensed radio amateur, and find bewildering the many different explanations, which range from folksy urban myth to Maxwell-Heaviside Equations, of what happens at the termination of a ...
4
votes
2answers
304 views
Impedance Matching for Short-Low Frequency Traces
Is it necessary to have impedance matching for short PCB traces if the frequency is lower than say 100MHz ? I've read somewhere that for a trace to be considered a transmission line it should have a ...
1
vote
2answers
189 views
Why is impedance represented as a complex number?
Let me know one thing. Why is impedance represented by a complex number when considering loss?
Usually it is said that imaginary part is because of loss. Is it True?
If it is true then does that ...
6
votes
3answers
415 views
Controlled impedance in presence of vias and through-hole components (PTHs)
We have some controlled impedance traces on layer 4 of a board. Layer 3 is a GND plane. Layer 5 is a 3.3V plane. Both planes are unbroken (they occupy the entire layer), with the exception of vias and ...
1
vote
2answers
626 views
When does controlled impedance on a PCB matter?
Suppose I have a PCB that contains a microprocessor, or an FPGA (a "controller"). This "controller" drives a single-ended signal to an LVDS driver IC and a single-ended signal to a connector that goes ...
