# Questions tagged [impedance-matching]

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

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### Antenna matching network not working as expected

I'm using a Nanovna and try to match my antenna. The VNA was calibrated directly on the PCB. The matching is split in two parts - Antenna -> 1st matching -> RF-Switch -> 2nd matching -> RF-...
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### What drives mechanical piezo device ultrasound maximum (sound) power output - electrical power or voltage?

Many definitions of piezo devices say that they convert mechanical energy to electrical (voltage) potential energy. This gives the impression that you want a high voltage to drop onto piezo device ...
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### Pi-matching impedance calculation for LoRa 868Mhz RFM95

I'm not an expert in RF, but I'm interested in understanding how to calculate an RF matching circuit for my RFM95W 868M LoRa node that indicates pin ANT terminated in a matched 50 ohm impedance ...
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### "Short" calibration

The following section from ST Micro's AN4974 - 'Antenna Matching' app note is a bit of a mystery. Is there a VNA / network analyzer guru out there who can tell me what the 4th line there is saying? I ...
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### Are T-parameters the same thing as ABCD parameters?

S-parameters can be converted to either T-parameters or ABCD-parameters, and both are considered a "transfer matrix". The conversion from S-parameters to T- or ABCD-parameters are defined ...
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### Can admittance (Y) be used to calculate reactance when L and C values are calculated from the Y12 and Y11 parameters like normal as X=XL-XC?

My original question sought to understand the relationship between S-parameters and reactance. In the process of trying to figure that out, this second question arose. The actual question is at the ...
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### Designing of a ribbon microphone (sort of) output transformer

I'm currently working on an experimental string musical instrument. It isn't my invention though. The source of inspiration called Dvina has an unusual pickup system. It senses the current induced in ...
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### How to correctly terminate a TTL line between two ICs?

I am designing a circuit to convert a 5ns ECL signal to an LVTTL signal of >10ns. The SY100ELT25 is used to convert the ECL to 5V TTL which is then fed into the SN74LVC1G123 to further reduce the ...
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### Impedance matching between 93 ohm and 50 ohm

I have a detector of an unusual impedance of 93 ohm connecting to a digitizer of 50 ohm through a coaxial cable of 50 ohm. Unfortunately I can not change the impedance setting of my digitizer. ...
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3 votes
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### Single wire electrodynamic pickup preamplifier (transformerless ribbon mic)

I'm currently working on an experimental string musical instrument. It isn't my invention though. The source of inspiration called Dvina has an unusual pickup system. It senses the current induced in ...
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1 answer
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### What is the link between conjugate matching efficiency and amplifier efficiency?

In the design of a class AB amplifier, there is part of the understanding that I miss. It is well-known that the maximum power transfer is achieved when the load impedance is the complex conjugate of ...
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### Impedance match a NFC Antenna to 50 $\Omega$

I have a hard time understanding how I can impedance match a homemade nfc-antenna to 50ohm. My antenna is designed by calculating the inductance based on the dimensions, windings and so on. R_ant is ...
2 votes
1 answer
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### Designing GPS matching network with TESEO and chip antenna

I am new to designing for RF and have a question regarding the design of the matching network for a GPS module I am working on. The datasheet of the chip antenna ANT161575ST-1202A1 recommends a ...
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### Does an antenna have to be impedance matched to its transmitter circuit or the transmission line from it?

I am still very new to RF and I am trying to understand Impedance matching, so my question could be stupid. I have already learned the basics of it, I know how to use Smith charts, which components to ...
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### How to simplify matching network LC circuit

I'm relatively new to RF design, and trying to implement a Micrel reference PCB antenna design (Heli-2). I am using a MICRF113 RF transmitter at 315MHz to transmit digital data using ASK (OOK). Here ...
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### How to calculate the output resistance of the CE amplifier, which has only a coil in its collector?

In order to be able to match the impedance, it is necessary to know the output resistance of the amplifier. In radio frequency amplifier circuits, there is usually a coil in the collector instead of a ...
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### How can one value describe the impedance of a group of reactive components at all frequencies?

The author of the textbook containing this circuit states that the filter input and output impedance is given by: Z = (L/C)^1/2 He then shows that by setting the source and load impedance to this ...
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1 answer
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### SX1272 bad performance

I want to use one shared antenna for the Lora/FSK transceiver sx1272 and LTE/GSM SIM700E module, with BGS12SN6 as a switch. I've matched the antenna with two conductor and validated the result with a ...
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### MIPI DSI/differential pair layout guidance

I have a display sample that I'd like to interface with a Linux SBC, the only issue is that the connector is not compatible. To make it possible to interface the two parts I've designed a PCB, trying ...
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### Source and Characteristic impedance of system - ST25DV NFC IC

i would like to design a antenna for a NFC IC ST25DV64K. The capacitance is 28.5 pF. And im using ST's design tool to calculate a inductance of my desired antenna design. But i dont understand how i ...
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### ST32WL RF Matching Network

I am adapting a minimal design based on the TTN Generic Node. I am trying to reduce the BOM and do not require the option to switch power. In the following diagram there are 4 RF signal I/O pins, 2 ...
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### SDR output to TV input -- besides impedance matching?

I'd like to connect the output of my software defined radio card, which is 50 ohms SMA, to the antenna input of a TV, to experiment a bit with signal generation. The obvious problem is going to be the ...
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### Calibrating a VNA

I am using the Siglent SSA3032A-R spectrum analyser which has a Vector Network Analyser (VNA). Before measuring the impedance of an antenna under test so that I can match this antenna, I have to ...
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### Impedance matching of an antenna with a cable

This is sort of a conceptual question. Suppose I have an antenna that is connected to a PCB via a 50 Ohm coaxial cable and a U.FL connector which is fed by some 50 Ohm PCB trace. Take this antenna for ...
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### Using Orcad To Simulate Pulsed Power System - Transformer Troubles

I am trying to recreate the system outlined in this paper: https://aip.scitation.org/doi/pdf/10.1063/1.1304873?casa_token=VSJdrwapVs8AAAAA:lydmRhcdbQcWRvhPyWSEzZHM7YHmAxcwvh1tr6elGc0jq-...
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### Tapered line for a SP4T RF switch

I need to use HMC241AQS16 brand RF SP8T switch on an FR-4 board. The RF ports of this QSOP package integrated circuit have 50 ohms impedance. But there is a problem, the leads of the chip have just 0....
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### S-Parameters Power amplifier impedance matching

I recently decided to conceive a 10W class 446MHz amplifier. I want to be able to amplify a 100mW signal into a 10W, for that i'm going for a two stages amplifier : SKY65162 to amplify the signal to ...
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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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### 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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