Questions tagged [impedance-matching]

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

114 questions with no upvoted or accepted answers
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1answer
810 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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1answer
66 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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0answers
85 views

Eliminate reflections on pulse signal transformer

I am trying to isolate an RLC ringdown signal via an RF signal transformer but I'm having trouble maintaining the signal integrity through the transformer. Below is the simple schematic describing my ...
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1answer
201 views

When are 1:1 baluns worth it?

I am trying to build an antenna to connect to the GOES-16 satellite (downlink at 1690,1MHz, linear polarization) with my SDR. My plans are using a 1m offset parabolic dish with a BiQuad feed, ...
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0answers
51 views

Antenna matching using L-sections does not always yield a "matched" solution

I created a program to compute the component values of a T network to match a reactive load (R+jX) to a 50 ohm source, based on the procedure outlined by M. Walter Maxwell in his book "...
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0answers
47 views

Different trace width signal transmission line

I have a really basic question. I am wondering what happens physically with the signal, if I have a change in a trace width (see picture below). My point of view is that you have a reflection of the ...
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1answer
240 views

Calculate the voltage across a load resistor for complex transmission lines

The following parameters are given: 500m homogeneous transmission line. ...
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0answers
42 views

Keep potential difference fixed for transformer's output

I have a source consisting of V1, R1, L1, and L2 to which my load R2 is attached: For the load, I have 10 or 100 Ohms. 1) R2 = 10 Ohms: Vrms = 315 V, irms = 32 A, P = 10 kW 2) R2 = 100 Ohms: Vrms =...
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1answer
215 views

Resistive on-die termination

It is widely known that resistive termination (e.g. 50 Ohm to ground) is superior when noise is no concern. Specifically in the block diagrams of RFICs I see many 50 Ohm resistors to ground directly ...
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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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0answers
47 views

Antenna matching circuit - weird behaviour

I have a 2.4GHz device with room for a Pi matching circuit. I cut J5 (to disconnect the MCU - brown line in layout picture), soldered the ground of the coaxial cable in the white region and the ...
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0answers
41 views

Matched termination of a microstrip using absorber foam

I have open ended microstrips in an RF circuit (operation freq. 18 GHz) and they cause unwanted back reflection into the rest of the circuit. Now, I wonder if it is possible to eliminate / reduce ...
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0answers
28 views

How to match Transformer output Impedance for Ultrasonic Cleaning Transducer

I have a transformer outputting the 240VAC 40kHz. The Transducer is 50W, 4100pF, 10-20 Ohm at resonance, ~40kHz resonance) The Secondary of the transformer is 12mH. I am trying to match the impedance ...
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1answer
43 views

RF output matching using baluns: LTC6946

The datasheet that I refer to below can be found here: https://www.analog.com/media/en/technical-documentation/data-sheets/6946fb.pdf I have a question about baluns. In the datasheet for LTC6946 ...
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2answers
64 views

Source Impedance Consideration for ADC

I recently used accelerometer ADXL335 in my academical project, this sensor gives analog output. I interfaced this sensor with microcontroller PIC18F458 using ADC module. It was successfully ...
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0answers
73 views

Impedance matching on oscillator

I have built an oscillator configuration at 4-7GHz. At 5.29GHz, the output of the oscillator has resistance R=-189-j*51. How can I use impedance matching and a bandpass filter since I have a negative ...
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0answers
65 views

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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0answers
37 views

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
64 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
83 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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1answer
661 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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0answers
328 views

Impedance matching of a RF power amplifier based on the s2p file

I'm designing the input/output impedance matching circuit for a RF power amplifier, based on the vendor supplied s2p file. I designed separately the input/output matching circuit at the given working ...
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0answers
85 views

Help needed to design a suitable energy harvester for TENG

I am in the process of desgining a scalable triboelectric nanogenerator (TENG) through which I can easily harvest and store electricity in a battery or a capacitor. A TENG can be modelled as voltage ...
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3answers
630 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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0answers
119 views

RFID reader antenna matching

I am trying to connect a RFID reader chip to an W3113 antenna on PCB. As said in datasheets, the antenna pin of the reader chip has internal 50 ohm impedance and antenna W3113 also has 50 ohm ...
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0answers
299 views

Impedance for TTL Hsync and Vsync Pulses

I'm just finishing up a sync combiner and audio/video PCB. I'm trying to impedance match my traces and I've done so for the 75 ohm RGB lines. Now I'm looking at the TTL level Hsync and Vsync lines ...
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0answers
116 views

Can antenna VSWR be corrected?

For this antenna, which cites a VSWR of 1.4, can that be improved (decreased) with the use of a matching network? Could the matching network be between the feed cable and the board or must it be ...
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0answers
321 views

F type female to SMA male adapter impedance question

I have a coaxial cable that I need to connect to a SMA female connect. The impedance of the cable is 75 ohms, and from online the SMA female connect is 50 ohms. Online there are a few places that sell ...
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0answers
316 views

LC matching or pi filter used in rf

I am working in RF and if i go through articles it is seen that in every point where the RF signal flows it is said we need LC matching networks or Pi filters, but i cant get the sole reason why they ...
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0answers
198 views

Antenna VSWR value and impedance matching claims by the manufacturer

Having larger value of VSWR is indication of improper matching. Eg. http://www.abracon.com/patchantenna/ACA-107-T.pdf this datasheet claims VSWR to be around 4:1 to 5:1 (which seems bad VSWR value to ...
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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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0answers
3k views

Drive a 50-Ohm load from a logic gate

I have a device that I'm trying to send a trigger too, it has a 50\$\Omega\$ termination and suggests a pulse between 2-5 volts, ~1\$\mu\$s width. The way things are set up, the trigger needs to come ...
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0answers
329 views

Antenna Matching 2.4GHz

i'm using a 2,4GHz transceiver with a differential output. A Balun with 50Ω Output is connected. I have 3 free places to add matching Components in π Topology. The antenna is placed on the other side ...
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214 views

When impedance matching networks aren't

As someone new to practical RF design (the theory is easy by comparison!), I have a relatively simple question when it comes to matching networks, and it has to do with best practices. Obviously, a ...
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0answers
262 views

antenna matching with lumped elements

Is there any resources online that describe how to match antenna elements to a TX line with a lumped element matching network? I've got a 50 ohm load and a TX line that i'm trying to match to a 2....
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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
538 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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1answer
637 views

RF coil impedance matching inconsistant result

I'm trying to do impedance matching from a signal generator (60MHz with 50ohms impedance) to a copper wire coil (6 rounds). The coil is connected by a wire (~6 meters long) with resistance 0.9 ohms. ...
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2answers
427 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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0answers
9 views

Impedance matching with L-matching network: cooking recipe

I would like elaborate in detail how to perform in detail practically impedance match between source and load via maximal power transfer using a L-matching network. Suggestion: I would like to ...
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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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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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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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0answers
53 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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40 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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0answers
34 views

Toroid core transformer: consequences of doubling the number of turns

In a 2N3904 common emitter RF amplifier circuit that I am building, the designer uses a FT37-43 miniature core with an 8 turns primary : 2 turns secondary ratio to couple to the next stage. I ...
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1answer
34 views

What is the purpose of inductance in PI impedance matching?

I am designing Wifi RF circuit with ESP8285 and need impedance matching to be done for 39+j6 Ω. As per suggested PI matching circuit in the datasheet simulate this circuit – Schematic created ...
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0answers
28 views

Matching circuit for GPS LNA needed?

Do you think I should add Pi matching circuit behind the dipole wire antenna input to achieve the highest LNA gain and low SWR and fine tune it by SimSmith program and NanoVNA ? The route is CPWG 50 ...
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1answer
58 views

LTC5599: why are these baseband inputs passed through 49.9 ohms and the capacitor + SPI

I'm designing a radar transceiver board using the LTC5599. In the datasheet for the part, there is a schematic that shows the circuit configuration for the evaluation board. Here is an image of the ...
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0answers
28 views

Is there a typical "Active Directivity" for LDMOS components?

Active Directivity is a measure of how much an amplifier's source match potentially affects its output impedance, or its load match affects its input impedance. High active directivity is a good thing....