Questions tagged [impedance-matching]

Impedance matching is a process of making one impedance equal to another another.

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36 views

How does SNR improve with impedance matching in a radio receiver?

I've seen basically every question and answer on here relating to impedance matching, and why you need it in RF but not in audio applications, and I'm still missing something. I initially was ...
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1answer
61 views

Can \$\Gamma\$ remain complex while calculating return loss?

I'm working on adding .s1p touchstone export support to the xnec2c NEC2 antenna simulator for Linux. I would like the S11 dB values in the .s1p to have both real and imaginary values. NEC2 calculates ...
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45 views

Placing the BPF and impedance matching on the output and on the input

I am working on solving a problem, namely I need to add input and output matching to my circuit and I am not sure where I should put them. Additionally, in the circuit I want to use a bandpass filter ...
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75 views

What happens if the there is a mismatch in impedance between signal generator and BNC cable?

My signal generator has 600 ohms in its internal output impedance (Picoscope 3204B). The BNC cable at my hand is 50 ohms, so is there any problem with the impedance mismatch? If yes how can I ...
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1answer
31 views

Does an LNA with a dedicated Vbias pin affect impedance matching?

I am optimizing an impedance match for an LNA in my target frequency range using a Touchstone s2p that Qorvo provides for the QPL9547 (datasheet). The Vbias pin is separate from the RF-in pin. I'm ...
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1answer
71 views

Tuning an antenna using a NanoVNA, Smith chart and impedance readings

I am new to antenna design and teaching myself how to optimize antennas using a VNA. I have created a monopole antenna on a PCB (i.e. a single length of track.) The antenna can be fed via a PI network ...
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1answer
51 views

How to convert complex conjugate impedance to a usual 50ohm impedance?

Let's say I have a complex conjugate for a component (RD16HHF1 @ 30 MHz for example): $$ Z = 2.93+j \cdot 3.51 $$ And I want to match that conjugate to a 50 Ohm. If I had something like 10 Ohm to 50 ...
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44 views

Input and output impedance matching for the HMC414 amplifier

I have a question about the impedance matching at the input and output of the HMC414 power amplifier. I don't know exactly where to put this matching, and I wouldn't want to make a mistake. The ...
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27 views

VNA Port Extension method

I have a PCB that has been handed to me that needs a match network setting between an SMA antenna and a Bluetooth module so operating freq = 2.4GHZ. I have a PICO 106 VNA and I have calibrated the ...
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1answer
223 views

Antenna Coupling via Capacitor 4: Calculation of Q of 'by hand'

Consider following coupling of antenna to a LC-tank via coupling capacitor C1 and on the right the replacement circuit of the antenna: I have become aware of a serious knowledge gap of mine with ...
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1answer
54 views

Impedance matching for ESP32-D0WD-V3 QFN 5x5 connected to uFL port

I'm designing a PCB that uses a ESP32-D0WD-V3 QFN 5x5 and I want to have a uFL port for 2.4Ghz Wifi/BLE. Directly from the datasheet, I get the following note: The output impedance of the RF pins of ...
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1answer
71 views

How to change track width in Altium for already placed tracks

I have a PCB with 8 layers and hundreds of tracks on different layers that already placed and length matched. I have to change again the track width to achieve the 50 Ohm impedance again because we ...
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3answers
117 views

Impedance Matching conditions for Matching Network

I'm trying to understand general concepts involved in impedance matching and I have question about the conditions which should be satisfied by the matching network. Assume we have in most general ...
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2answers
79 views

Antenna Coupling via Capacitor 3

This question appears at first glance to be almost identical with this one Antenna coupling via capacitor but I think that in the following case the involved coupling capacitor might play a different ...
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1answer
159 views

Impedance matching with L-matching network: cooking recipe

I would like to try to elaborate in detail how I think one should perform in detail practically impedance match between source and load via maximal power transfer using a L-matching network and whould ...
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1answer
67 views

Does the impedance profile of flexible PCBs include the adhesive layers?

I'm looking at this page on PCBway and trying to get these values into Altium in order to get the right impedance profile. As I understand, I should use the finished copper thickness to get the right ...
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1answer
101 views

Guideline for Impedance Matching (simplified cases)

Dealing with impedance matching of RF networks one facing two common techniques: (a) maximize power transfer (b) minimize reflexion of signal waves In this question I have tried to develop some kind ...
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102 views

Maximum power transfer and minimization of signal reflection: When should what be applied

Impedance matching is the practice of designing the input impedance of an electrical load or the output impedance of its corresponding signal source to maximize the power transfer or minimize signal ...
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3answers
129 views

Maximum power transfer and minimization of wave reflection: Understanding the difference on intuitive level

It is well known that there are two usual methods in impedance matching: if we have a network consisting of a source with impedance \$Z_S\$ and load with impedance \$Z_L\$ then we have two options to ...
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4answers
113 views

Difference between tuning and matching for transmitter/receiver circuits

I would like to find a coherent answer to following question: What is precisely the core difference between tuning and matching in HF electronics, especially in design of transmitter/receiver circuits?...
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35 views

MIPI Trace spacing and ground plane size

I am designing a carrier board for the nVidia Xavier. While reviewing the documents for the MIPI interface, one of the requirements I don't understand is trace spacing: Does this mean that my traces ...
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2answers
100 views

Simplest way to check if an audio level is line or micro?

I can check level audio on a VU Meter or dBFS meter. What's the simplest way to check if an input audio level is line or micro? Can I use a multimeter?
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3answers
147 views

How to terminate branches in a transmission line

some research has unfortunately not led to a clear result. Branches in transmission lines are not desirable, but if they are unavoidable the question arises how to properly terminate the individual ...
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1answer
97 views

Account for Via Stubs When Calculating Impedance?

I'm working on an eighteen-layer board right now. Almost all of the signal layers have high-speed, single-ended traces that should run up to 15 gbit/s. The vias for these high-speed traces will be ...
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2answers
50 views

Impedance calculation issue

I am a strange calculation of Zin, Zline and ZL. As tan(pi/2) is 0, why can't we just cancel the j part, and yield Zin = ZL but as it demonstrated, using tan(pi/2) to divide, which should not be ...
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66 views

Understanding the input characteristics of an RF power transistor (2SC2237)

I've had this 2SC2237 RF power transistor from Mitsubishi for quite some time and I've finally found a project for it. The datasheet can be found here. The first thing I need to do is figure out its ...
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1answer
53 views

Match SMA antenna input connector to 50ohm

I'm using an "IOT" radio module designed with a 50 ohm single ended antenna output. The working frequency is about 868 MHz, the maximum transmit power is 14dBm. The module antenna output is ...
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1answer
60 views

Designing a bode diagram circuit

I have realized some low pass filters with a nominal cut off frequency around 10kHz, which I will use in combination with other filters to eliminate noise on DC and quasi-DC signals (around 30Hz). I ...
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1answer
64 views

How should I route the ground plane under a RF trace with a LC balun?

I'm designing a PCB with a ESP32-PICO-V3, with a RF output to a 50 Ohms U.FL (Micro-Coax) connector. The chip supports WiFi and Bluetooth in the frequency range 2.45 +/- 0.45 GHz. Right now, I have a ...
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56 views

Impedance matching in Transmitter Circuit

Consider the FM transmitter circuit from here (https://eeeproject.com/fm-transmitter-circuit/) with circuit diagram In this question (Antenna in Transmission & Receiver circuits) I was going to ...
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3answers
185 views

Can I use 50 ohm cable with 75 ohm tv antenna?

Can I use 50 ohm cable with 75 ohm antenna (without any adapter)? I found on the internet that 75 ohm cable can be a problem with 50 ohm antenna, but does vice versa make the same problem? Or the ...
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2answers
128 views

6 Layer PCB 50 ohm Impedance Matching

What information do I need from the PCB manufacturer to create a 50 ohm impedance trace on my 6-layer PCB?
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1answer
70 views

RF Impedance Matching in Altium

I'm trying to route a LoRa module to an SMA Antenna on my board (first time tracing RF signal). Shown in image below: I adjusted my layer stack up for my 2 layer board, 1.6mm thickness and added an ...
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1answer
61 views

Impedance matching and circuit power

I need to match the input and output impedance of this part circled in red. In theory this stretch in red represents a coaxial cable with an impedance Zo=75Ω I need some power that can be activated by ...
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1answer
107 views

Ground plane placement in relation with LORA spring antenna

I am making a simple lora transciever and absolutely want to fit it on a single side dual layer 0.8mm thick pcb. Which makes impedance matching a bit tricky with 53mil traces... Here the form factor ...
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2answers
88 views

Suppose there is a standing wave in a transmission line at high power. Will the nodes of a wave 1 ft apart be hotter than the antinodes?

I was looking around for an evening and could not find an answer. I am also fuzzy on the exact electromagnetic physics principle of why a reflection occurs (please do not say "because the ...
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1answer
84 views

What value series resistor should I use for USB data lines when two ICs require different impedance values?

I'm using a USB hub (TUSB2036VFR) that communicates with an ATMEGA8U2 and an FTDI chip. The incoming USB signal comes through an isolated USB communications chip ADUM3160BRWZ. The TUSB2036VFR requires ...
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1answer
45 views

HDMI green signal not working as intended

I have been working on a host PCB for the Raspberry Pi CM4, and wanted to add some HDMI output. The beauty of the CM4 is that you don't need any further chips, just some current limiting chips on the ...
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2answers
130 views

Matching network and filter design

I am designing matching network at 868MHz frequency. I have a source impedance of Z=15.27-j1.27. In order to match that with 50 Ohm, I implemented LC matching network (red color). After that in order ...
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2answers
78 views

Guideline for Board-To-Board 2.4GHz RF design - multi ESP32 module board

I am working on a design with multiple ESP32 on one board. The selected ESP32 does not have internal antenna, instead it has an IPEX connector for external antenna. On the device we would like to have ...
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0answers
42 views

Impedance of loop wire

I need to calculate the total impedance of a 3 mm diameter wire loop of 320 µm magnet wire with 5 mm of feed length at 3 GHz. My approach is: $$ \newcommand{\subs}[1]{Z_{\text{#1}}} \newcommand{\Z}[1]{...
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4answers
771 views

Attenuation for high frequency when using coaxial cable

Can someone tell me why high frequencies (1 MHz sine signals) are getting attenuated in the below case. I have a function generator with 600 Ω output impedence. I connect this output to a digitiser ...
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5answers
2k views

Trace impedance ohm meaning

I've been trying to understand the principle of trace impedance (single ended and differential) for a while, read several articles (all the best google has to offer), but I have still some serious ...
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3answers
154 views

How can I match a transmission line impedance on the source side?

Suppose that I want to transmit a signal by a coaxial cable to a high-impedance load. The signal is a single-ended TTL (3.3V) single square impulse from an FPGA output. The package of the FPGA is LQFP-...
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1answer
45 views

Why for DDR3 driver with a low-impedance output undesirable?

I was reading Micron Point to point DDR3 technical note. It says as follows: In point-to-point designs, the memory’s position is typically quite close to the controller, which results in short data ...
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2answers
439 views

What does a 50 ohm coax "look like" when neither the source nor the load are matched to it, and the center conductor and shield are used for signals?

Say I have a π-network filter for which the inductor is on a separate board. For convenience, I use a 50 ohm coax (4" long, frequency is 13.56 MHz) to connect to the inductor, using the center ...
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31 views

NB-IoT module - Connect ANT pin directly to RF connector without matching circuit?

Some months ago I did the layout of a board with a GSM module SIM800L and below is shown the antenna circuit that was used. We assembled 200 PCBs with R22 = 0R jumper and C28 and C29 not populated and ...
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4answers
897 views

Impedance matching between two ("prosumer") audio devices [closed]

I would like to send an audio signal from a Presonus HP4 headphone amplifier to a Zoom H4n "handy" recorder, but I am having difficulty understanding the role of impedance in this setting. ...
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2answers
90 views

How do you combine 3 existing band pass filters to make a triplexer with 50 Ohm ports?

I have designed 3 microstrip band pass filters that each have a good 50 ohm match at the target frequencies (2 m, 70cm and 13cm bands) and I want to combine them into a triplexer to split one signal ...
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1answer
67 views

Impedance Matching Necessary for short HDMI trace?

So, I am working on a design that uses HDMI for media output. The PCB has a connector for the Raspberry Pi CM4, and usually what I would do, is to do a "differential pair route" where I do a ...

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