Questions tagged [impedance-matching]
Impedance matching is a process of making one impedance equal to another another.
792 questions
0 votes
0 answers
35 views
Modeling RF Impedance Matching PCB Geometry
I am designing RF amplifiers, and I often use LDMOS transistors with unmatched inputs and outputs. My goal is to learn how to model and simulate PCB impedance-matching geometry on a computer before ...
- 100
0 votes
0 answers
67 views
How to layout a transmission line for impedance matching when using a chip antenna
I will be designing a PCB layout for a LoRa module very similar to this one, but with a chip antenna instead of a U.FL connector. It seems that this one has a pi matching network for matching the ...
- 173
2 votes
2 answers
144 views
Why aren't the antenna terminals on a WiFi card terminated at their characteristic impedeance?
I have noticed on several occasions that some internal WiFi cards and some motherboards with WiFi provide open, unterminated, antenna connections. I am starting with the following assumptions: A WiFi ...
- 151
1 vote
1 answer
66 views
Where should I connect my VNA for impedance matching on a wireless module?
I’m new to RF design and need some guidance. My board has a wireless module where the ANT output goes through a matching network and then to a U.FL connector, which connects to the antenna. This chip ...
- 11
1 vote
1 answer
62 views
Impedance and via fence for BLE antenna feed on nRF52805 flex PCB
I’m designing a BLE temperature sensor using Nordic’s nRF52805 (WLCSP) and a Johanson 2.4 GHz antenna, built on a flexible CopperFlex PCB (JLCPCB). The layout has a short feed line between the ...
- 191
0 votes
1 answer
89 views
Mismatch between input return loss and output return loss
I have a filter, which shows a mismatch between input return loss (S11) and output return loss (S22). They are not equal at the frequency of interest, which is around 36 GHz. Would this affect the ...
- 111
0 votes
1 answer
86 views
Schematics Review, GPS module with a custom bias-tee and an active antenna
Description: This is a simple GPS module design based on the TESEO-LIV3F from STMicroelectronics. Review request: I’m particularly concerned about the bias-tee section and the chosen LC values. I’m ...
- 109
1 vote
1 answer
70 views
RF Connector in GSM antenna trace
I'm building a board with a A7682E GSM radio module. About antenna, the hardware integration manual states this: Is the "RF connector", the one I should plug the VNA into for impedance ...
- 639
0 votes
0 answers
62 views
STM32WL33: How to avoid using a RF switch for TX and RX path
I am designing the impedance matching network for TX and RX pin for the STM32WL33C8 similar to the reference design: So far I have calculated the matching impedances to make the impedance 50 ohm in ...
2 votes
3 answers
618 views
Single OpAmp Impedance Transformation: 75Ω to 5Ω/150Ω
I need to transform a 75Ω source to either 5Ω or 150Ω output impedance using a opamps (i know a transformer is an easy solution, but I want to solve this with a solid state device). Source impedance: ...
- 439
0 votes
0 answers
87 views
LC impedance transformer that has frequency independent input and output impedances?
It is possible to build a low pass filter (alternatively high pass, band pass, or band stop) which has a specified input impedance when its output is attached to a load with that same specified ...
- 34.6k
1 vote
3 answers
161 views
Impedance matching Filter+Load
Consider the scenario where we have a source of source impedance \$Z_s\$ transmitting voltage to a load of \$Z_l\$ through a line of characteristic impedance \$Z_0\$. Assuming all three are matched to ...
- 209
4 votes
5 answers
331 views
Why don't transformers used for impedance matching cause reflections?
Original question: I understand transformers are often used for converting impedance, for example the secondary feeder loop on a loop antenna. However what I can't get my head around is why ...
- 155
1 vote
1 answer
131 views
According to this AppNote, I don't need to match source and load impedence. Why?
I am working on a board to distribute PPS in my house and came across this AppNote from Renesas. It shows that in a 50 ohm environment, I can just terminate to a 50 Ohm resistor, without worrying ...
- 13
2 votes
1 answer
93 views
How to determine maximum RF power rating of an air core impedance matching inductor at HF frequencies?
Experimenting with single-band, fixed-frequency, end-fed, half-wavelength vertical antennas in the HF frequency spectrum. These near-ground level feedpoint vertical antennas require an impedance ...
- 39