Questions tagged [impedance-matching]

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

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2answers
44 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
73 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
175 views

Question on Matched 3dB attenuator

For the second picture below, how to derive the expression for Vo ? I suppose there is some in-betwen maths that I missed out. Note: 41.44 ohm is the parallel equivalent for (50 ohm + 8.56 ohm) || ...
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1answer
496 views

Matching impedance network for an LC ladder network

Let's say I have a 5 stage L-C ladder network with L= 4.7 micro Henry and C= 60 pF. The characteristic impedance of the network becomes 280 ohms (square root(L/C)). However, from circuit analysis, the ...
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1answer
61 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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3answers
631 views

Modern piezo microphone impedance-matching circuit

I want to record sound with a piezo transducer. I am connecting it to my sound card's input which has a good mic pre-amp. The levels are quite good and the sound seems quite clear but there's a lack ...
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1answer
92 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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1answer
96 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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1answer
439 views

How to calculate the output impedance of an adjustable RF amplifer to match the input of a mixer using SA605 chip?

I have an FM receiver design I wish to implement using the SA605 chip. The stage before feeding the signal to the SA605 chip is an RF amplifier. I know I have to impedance match between each stage to ...
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1answer
244 views
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3answers
125 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
97 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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0answers
56 views

How does impedance matcher between amplifier and antenna work?

I'm trying to do impedance matching circuit for my project. So there is a square wave generator which is generating square wave obviously. Then amplifier, impedance matcher and antenna. I want to emit ...
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2answers
210 views

How to connect a low impedance RF amplifier to an antenna?

I'm trying to maximize power transfer from my amplifier to my custom antenna, but am unsure about how to properly impedance match the system. My amplifier has an output impedance of 4Ω, but is ...
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0answers
33 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
97 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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1answer
669 views

IBIS Model Characteristic Impedance

I have tried to understand how to match my 50 ohm pcb trace, which is carrying a high-speed data signal, with a digital chip's input pin. The problem is that I don't understand why the calculations ...
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3answers
138 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
167 views

Difference in the characteristic impedance of a low frequency signal

In one of my PCB design, for a RS 485 signal termination resistor of 120 ohm is there. But the differential characteristics impedance of the signal is taken as 100 ohm instead of 120 and the signal ...
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1answer
67 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
48 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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1answer
281 views

PCB Antenna Tuning

I am trying to tune an antenna as seen above, using this wonderful Smith Chart Tool. It needs to match 35 + 10j characteristic impedance. I have found a tool like the Microstrip Impedance Calculator ...
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1answer
389 views

ADS Simulation: Schematic to find input impedace

I'm following a paper, using ADS, to find the input impedance of a shunt Schottky diode. The paper's schematic is Fig. 1, and my schematic is Fig. 2. The point is that, I could not get the same result ...
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0answers
57 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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4answers
9k views

Question about trace length matching patterns for high speed signals

A colleague and I had a discussion and a disagreement about the different ways high speed signals can be length-matched. We were going with an example of a DDR3 layout. All the signals in the ...
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1answer
59 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
43 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
53 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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2answers
117 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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0answers
55 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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1answer
386 views

Impedance mismatch in LISN for EMI/EMC test

I am currently designing LISN for CE-102 test.The schematic of the circuit is provided below. When I connect the circuit to the network analyzer the impedance is coming as shown below expected graph ...
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1answer
62 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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2answers
107 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
333 views

What is the purpose of these components in an LC Balun?

I'm trying to understand an antenna impedance matching / balun network that I came across in the receiving signal path in the schematics for the STEVAL-FKI868V2 S2-LP Evaluation Board, shown in the ...
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4answers
560 views

Impedance Matching a capacitive source

I am trying to work out how to match a current source coupled with a capacitor to a 50 Ω load for maximum power transfer. Specifically I have a 6pf PIN photodiode which driven by a 2.5 ghz optical ...
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1answer
812 views

Qucs model for 2.4 GHz matching circuit

I am designing a matching circuit for an EFR32BG13 SoC. The current board layout looks like this: In addition to the visible layers (top and bottom), layer 2 is a solid ground plane and layer 3 is a ...
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2answers
662 views

Find impedance matching in a quarter wave transformer

I would like to know if there is a way you can find the impedance that has to be set between the load \$Z_L\$ when it is complex and the characteristic impedance \$Z_0\$ to have impedance matching ...
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1answer
60 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
85 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
79 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
43 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
428 views

Troubleshooting noisy FET buffer for contact mic

I'm trying to follow the schematic on this page to create a preamp/impedance matcher for a balanced piezo contact mic. I've reproduced the schematic below. I've built it on a breadboard and I'm ...
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2answers
122 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
63 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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4answers
760 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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0answers
41 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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9answers
16k views

Why is 50 Ω often chosen as the input impedance of antennas, whereas the free space impedance is 377 Ω?

In order to efficiently deliver power to a different part of a circuit without reflection, the impedances of all circuit elements need to be matched. Free space can be regarded as a further element, ...
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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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1answer
663 views

Quality Factor and Frequency Bandwidth in a matching network

it is known that the Quality Factor appears in the formulas for transformation of an impedance series bipole to a parallel one. A simple example is this one: Now I have three questions: 1) I have ...

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