Questions tagged [impedance-matching]

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

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How does Impedance matching equation work out from original link?

From this link: L-Pad Impedance Matching Equation How do you get those two equations? They do not look like a voltage divider formula, do they? Questions repeated here: First answer from Adil ...
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300 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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Impedance Matching between Source and Load

I am having this basic doubt In the basic crude basic block diagram, we have a source, transmission line and load, all having an impedance of 50Ohms. But according to maximum power transfer theorem, ...
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1answer
29 views

Impedance Matching of an Antenna

I am reading about antenna design and have a few questions which I could not get clarified. I read about "Stubs". I got to know that Stubs are used for impedance matching of an Antenna either by ...
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2answers
422 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
325 views

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

I have a FM receiver design I wish to implement using the SA605 chip. The stage before feeding the signal to the SA605 chip is a RF amplifier. I know I have to impedance match between each stage to ...
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0answers
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Match a Crate 150w (1x8 ohms mono/ 2x4 ohms stereo) to cabinet 2x12 Celestion 70/80 each 80w at 8 ohm [closed]

I have a homemade cabinet with two celestion speakers seventy 80 with rated 80 watt at 8 ohms each one. And a Crate Powerbank amplifier with two outputs. One 150 watt at 8 ohms bridged mono out. Ando ...
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1answer
106 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
54 views

Voltage Follower Circuit Output Changes based on Load Resistance

I am trying to simulate a circuit which can act as a voltage follower for a headlight. I simulated the circuit using CircuitLab. I simulated two conditions: When headlight resistance is 10 Ohm. ...
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4answers
613 views

Why should a receiving antenna be impedance matched to 50 ohm instead of a lower impedance?

I'm in the process of getting to grips with RF design and am having some trouble understanding why we should always match antennas to \$50\Omega\$. I understand from the maximum power transfer ...
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Why is an attenuator placed on the scope end and not the PCB end?

I've noticed when adding an external attenuator between PCB and the scope (1MOhm) that it is placed in this manner: PCB -> SMA Socket -> SMA Cable Plug -> SMA Attenuator -> SMA-to-BNC -> Scope Why ...
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Antenna impedance matching within metallic enclosures

What im trying to achieve is kind of an chip antenna breakout board, since it must sit within a metallic groove. The plan is a PCB of 10mm diameter with an U.Fl connector on the back and an antenna ...
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1answer
29 views

Should I cut away the ground pour above a diffpair on the first inner layer, which are Z-matched to the ground layer (L2)?

I'm routing diffpairs on the 1st inner layer of a 4-layer pcb which are Z-matched to the 2nd inner layer which is entirely a ground pour. The top layer has traces and routing AND also a ground pour ...
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1answer
42 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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2answers
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Speaker impedance and voltage

There is a device which has output impedance 150ohms. If my headphone has either lower(30ohms) or higher (400ohms) impedance can I use it or sound will be too low/high and it will be unsable? Also, ...
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Determining Z1 for voltage divider of RF Matching Circuit

I have a problem where I was given an RF circuit with a series RL load. I am tasked in finding a matching L circuit and determining the values of the components. I used a smith chart to determine that ...
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1answer
26 views

How to calculate component value of a matching network

You can already expect my knowledge level In antenna designing (newbie). This may be or may not be a stupid question. The reason is I don't know about this very much. Iam designing a PCB for ESP32 ...
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1answer
523 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
658 views

Impedance Matching: Minimum Reflection vs Maximum Power Transfer

The minimum reflection is achieved when the two "circuits" being connected have the same impedance. This makes sense because all the components of the wave can propagate without needing to be modified....
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1answer
29 views

Understanding series open stub tuning

I recently had an assignment where I had to use open stub series tuning to find a way to maximize power delivered to the load from the generator. I understand that power delivered to the load is ...
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1answer
58 views

Can 3Ω speakers match 4~16Ω amplifier? [closed]

I have a set of Samsung home theatre system. The Samsung DVD player is no longer working. I would like to get a new amplifier and reuse the 5 existing Samsung speakers. But the existing speakers are ...
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1answer
296 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
35 views

Padding/impedance matching of a phono input

My old stereo amp got coffee spilled on it. I replaced it with the latest model from the same manufacturer. I am an old-world person, and prefer simple approaches - i.e., radio buttons to select ...
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1answer
34 views

Best way to connect a coil to a source with 50Ohm impedance?

I have a 50Ohm impedance source at 800Mhz and a coil with complex impedance Z = 0.0028 + j3973.9121 Ohms at 800Mhz. I would like to maximize the current through the coil and protect the source. I ...
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1answer
117 views

Connection between RF output to the source for minimum loss and maximum power transfer

The bottom device in the left image is an RF generator with ratings 230V, 15A (max), 13.56 MHz and variable controllable output power up to 1250 W. The top device is an auto match. The metal strip ...
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1answer
24 views

Which Signals require impedance matching?

There are two types of connections in PCB. Which are in between the PCB.(e.g- A SD card is connected near to Controller) One is going out through some connectors.(Some UART or SPI going out through ...
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32F746GDISCO Stackup and Ethernet Impedance

I have an example board with PCB about the ethernet application. I noticed a mismatch between stack up and ethernet lines, or something else I don't know. Ethernet Lines are drawn with 0.125mm and its ...
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Find PCB Antenna impedance and matching circuit

I'm working on a project that uses NFC interface. I need to design two antennas: one for the RFID tag and another for the NFC initiator. I decided to use the design proposed in the evaluation kits. ...
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1answer
48 views

Questions regarding AFG3000C function generator

I have a new function generator - model AFG3000C. I am having difficulty in understanding certain terms related to this function generator. I have tried online searches, but I couldn't get what I ...
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1answer
110 views

500 mW RF amplifier for 170 MHz design

For a new project I need to build an RF amplifier for continuous-wave with about 500 mW (27dBm) output at 170 MHz. It doesn't need to transport data, it is only for measuring purpose. The input ...
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0answers
30 views

Ferrite antenna impedance matching

I want to use a tuned ferrite antenna with my RTL-SDR. From what I understand at the point of resonance, only the real (resistive) impedance remains. This should be a few ohms for the resistance of ...
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1answer
239 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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29 views

LM386 High Pass Filter Design? [duplicate]

I was looking into the datasheet for the LM386, and they provide an example implementation circuit. At pin 5, as I understand it, you can expect an amplified signal with a DC offset of Vcc/2. I can ...
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1answer
394 views

Optimizing short antenna for 27 MHz

(It's really a continuation of a previous question but it is old so I decided to ask a new one with more detail) I have a colpitts oscillator designed for 27 MHz going into a short monopole antenna ...
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4answers
418 views

Current to Voltage Feedback Capacitance for SiPM

I'm having an issue with my Silicon Photomultiplier (SiPM) feedback circuit. The output is not behaving as expected. I apologize for the layout of the schematic, but this was the best way I could ...
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1answer
265 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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2answers
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LC Filter / Matching - Why does this cap help?

this is my first question on the site, so please let me know if there's something I can do to write it more helpfully. The Problem: I'm building a small radio. At the output of my mixer, I need to ...
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3answers
649 views

(When) Can I use Cat5e wiring to carry a POTS signal to a DSL modem?

According to this answer by @asndre, It is very bad idea to use Cat5e-based wiring/cabling to establish a xDSL connection. However, my telephone/internet provider technician recommended -- and ...
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0answers
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Why circuit from antenna datasheet is like this?

I'm designing circuit with nRF52810 BLE SoC and I have decided to go with ceramic chip antenna because it seems easier than designing printed antenna. The problem is that I'm just a 1st year student ...
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1answer
58 views

At which point and how to connect VNA on the PCB for antenna tuning?

I am working on a 2.45 GHz(Bluetooth) project. I have used a ceramic chip antenna with 50 Ω impedance for this board. I've placed a Pi network close to the antenna and also I have used an integrated ...
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1answer
63 views

Input/Output Impedance of DC/DC converters and Impedance matching

I am interested in understanding how do DC/DC converters achieve impedance matching for maximum power transfer applications. After visiting this entry, you can see in the "impedance matching" ...
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1answer
68 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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1answer
64 views

Is this an Impedance Matching Curve?

This may be a very quick answer, I had a test that was set up like this. The primary inductance of the transformer was roughly 0.022H and the inductance of the secondary of the transformer was 0.045H. ...
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2k views

Conditions for maximum power transfer in an AC circuit

So, if we're given the circuit below: Known values are: \$E_g=35 \ kV\$ \$f=685 \ kHz\$ \$\underline{Z}_g=150 \ \Omega\$ \$\underline{Z}_p=(200-j300) \ \Omega\$ We have to calculate \$L\$ and \$C\$ ...
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1answer
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Designing a bluetooth audio unit for speaker

(Cross posting from Sound design stack exchange since it was declared off topic there) I have a sony speaker from an old Home Theatre System that is broken now leaving the standalone speakers in a ...
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1answer
155 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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1answer
267 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
117 views

Measurement of s11 with reduced power on NanoVNA

I am developing a 10.7 MHz IF amplifier for a radio receiver. In order to match the input to the output of the driving mixer stage (330 ohm) I need to measure the input impedance. I did the ...
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1answer
42 views

Impedance matching an amplifier near 1 dB compression point

I am using a RF amplifier (model: Minicircuits LZY-22+) to drive 6.5 MHz oscillation in a coil. I am using an antenna tuner (model: MFJ-969) to impedance-match the output of the amplifier to the coil. ...
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1answer
28 views

What is the general procedure for matching networks when there are multiple circuits are connected back to back?

If I have two circuits like the one shown above (Rx antenna -> block1 -> block2 -> Tx antenna), where all should I add matching networks. How should I look at the impedance while doing the matching ...

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