This tag marks questions related high frequency (radio) circuits.

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2
votes
2answers
68 views

How to properly wind a high frequency / high voltage transformer?

Please, is there any practical tip / caveat I should be aware, when winding a high-frequency transformer? I'm used to wind 50/60Hz transformers and they do work ok, but now I'm trying to make a high ...
0
votes
2answers
38 views

Inductance values over the frequency

Does inductance vary over frequency in passive components. Consider a Coax cable for example, does the inductance value change as a function of frequency, lets say from 5GHz to 100GHz, does the ...
0
votes
0answers
49 views

1Hz to 25MHz programable square wave [on hold]

I need to design a device that is capable to produce 1Hz to 25MHz square wave. The resolution should be 0.03Hz or less. So for the control side I will use an AVR, but I don't know what solution do I ...
0
votes
1answer
52 views

high speed differential nets crossing on PCB

I have 2 ICs working at 9 gbps. Output of 1 IC is differential CML pair and it goes as input to other IC. On PCB layout, if both ICs are placed on top (component) layer, one ICs positive pin is in ...
0
votes
2answers
79 views

Why is a reference plane needed in differential signalling?

As I understand differential signaling, return current goes via the "-" (minus) line, so why we do we need to provide a reference ground plane for differential signals?
0
votes
1answer
56 views

Why prevent high frequency input into the loud speaker using a low pass filter?

As much information as possible about this figure would be helpful From what my professor said, "Q2 oscillates when we connect a Loud Speaker, this might generate high frequency signals, so we use ...
0
votes
1answer
75 views

How to simplify opamps in circuits for limit analysis

I know that when simplifying electronic circuits for limit analysis you can e.g. replace capacitors with closed lines and coils with open lines. e.g.: the equivalen at high frequencies would be: ...
3
votes
1answer
82 views

How to add frequency control feedback loop to a circuit for an inductive heater

I am interested in a design made by an MIT student, Bayley Wang, several years ago for a 30kVA induction heater. One engineer on this site with professional expertise examined this circuit and ...
2
votes
1answer
55 views

High Frequency Start Arc Generator For Pulse Arc Welder

A little back story - I'm a network security engineer turned bench jeweler. I built a capacitive discharge spot welder. It's an awesome unit, and works great, but it's not exactly what I need it to ...
1
vote
3answers
74 views

Use a wooden frame to avoid dissipation of high-frequency current?

In reading a description of a 32-kilowatt induction heater of the spark gap type by Frank Curtis (p. 29), I see the following passage describing the enclosure: The entire assembly is mounted ...
3
votes
1answer
89 views

Does thhis crystal circuit works?

I need a tiny oscillator circuit for testing an application. Now I haven't much experience in creating oscillators so I would like to use this Collpits-circuit: I only need the carrier wave so I ...
0
votes
3answers
132 views

Why does this circuit produce a static noise?

I was just designing this Common emitter transistor amplifier this morning. simulate this circuit – Schematic created using CircuitLab I have removed the input in the circuit ...
-1
votes
3answers
144 views

How to turn a 200~Khz AC voltage into a proportional DC voltage that does not exceed 3.3V

now, I have an induction heater, which runs at 200 Khz, and near the coil of the induction heater is another coil, now, if they coil is near the IH's output, currents will be induced into it, yes? ...
0
votes
1answer
81 views

Unnatural AD9850 Output Attenuation

Yes, another question about this DDS. However, I think mine is sufficiently different from the others I've read. I purchased an AD9850 board on Amazon for $17 from "NooElec" (see here). I've been ...
4
votes
2answers
437 views

How to generate high frequency clock with high stability from a microcontroller?

I am using TivaC launchpad TM4C123G microcontroller, to generate a clock of 40 MHZ but I tested it on the oscilloscope and it doesn't look like a square wave it's more like a sinusoidal here is a ...
2
votes
0answers
58 views

How to properly store big values in parallel SRAM

For a project I need to determine the frequency and phase-shift of up to 16 channels. The frequency range is 0 to 3 kHz and the signalform is square. My first idea was to use the following circuit ...
1
vote
1answer
56 views

The gain of two op amps in series at high frequencies

I have a following circuit with two op amps in series. What is the gain in dB of this circuit at 13 MHz relative to its DC gain? The 13MHz is well out of the normal operation region of the op amp. ...
1
vote
2answers
115 views

Why does my 74AC04 not invert my 14.31818 MHz frequency?

I have a crystal oscillator (full can) running at 14.31818 MHz. When I put that on my scope, it shows about 14.3~ MHz. My scope is a ...
5
votes
4answers
672 views

High frequency signal using low frequency micro-controller

How do micro-controllers running at slow clock frequency (under 100 MHz) produce high frequency radio signal (2.4 GHz for example)? For example - ESP8266 runs on a clock speed of 80 MHz but is capable ...
0
votes
2answers
93 views

High Frequency Transformer Design and Materials [closed]

I have designed fly-backs and inductors and understand the basics about flux density, saturation and core losses. What I have never been very clear on is design of SMPS transformers. I get the concept ...
3
votes
2answers
172 views

Extra spacing between some traces and the ground plane

I have seen several designs where there is extra spacing between some traces and the ground plane. For example, see the traces between the points A and B or C and D in the following picture (this is a ...
2
votes
1answer
74 views

How to measure parastic capacitance of a trace

I have a 24 MHz, crystal on my board and datasheet of IC defines the load capacitance between 5-9pF. The reference design I follow don't use any load capacitor. My traces look like this: shorter ...
2
votes
1answer
87 views

Open-circuit time constant method

Can anyone explain how Rgd is obtained? I plugged both Ix into Rgd expression but did not get the correct result. here is my attempt I cannot proceed. What did I do wrong? How can I get rid of ...
4
votes
1answer
297 views

Why Increasing Collector Voltage Reduces Collector-base Capacitance

I'm looking at some transistor radio circuits and the book I'm following makes the following statement with regard to AC gain: "By raising the DC voltage at the collector, the internal collector-base ...
5
votes
1answer
123 views

Aternative diode classes for high frequency(10GHz) applications

I'm trying to design a voltage clamping circuit for a 10GHz signal. I've modeled it in spice using several schottky diodes and it works but only when the signal pulse is at least a few nanoseconds ...
0
votes
1answer
62 views

Can a Doppler shift of 3Hz be detected in a frequency of 1.2 GHz?

Well! I am working on a project where i am supposed to detect a frequency shift of 3HZ in a carrier frequency of 1.2 GHz. My team has decided to bring down the frequency at about 100Hz or less where ...
1
vote
1answer
64 views

Function to Simulate Realistic Waveform

I need to simulate a realistic signal voltage triangle waveform in Mathematica. I know that a real waveform won't have sharp corners, but I don't remember exactly what a real triangle wave looks ...
4
votes
2answers
537 views

Self resonance frequency for MLCC capacitor

Is there a general self resonance frequency characteristics for MLCC capacitors? If I make a RC low pass filter, say using 1kohm and 15nF 0603 with fc = 10.6kHz, I guess it won't work as LPF beyond ...
3
votes
5answers
404 views

Large Frequency Divsion

I am currently trying to design a circuit that needs a large frequency division, 25353 to be exact. I'm aware that I could do a large complex flip flop arrangement to achieve close to the desired ...
-4
votes
1answer
98 views

High power 11 to 22Khz amplifier

I have built a circuit using a 555 IC. (Oops sorry)The purpose is to control the neighbours barking dogs. The output varies between 11 and 22kHz by means of a pot to have the most effect. What are the ...
0
votes
1answer
474 views

How can i make a ceramic piezo operate at a specific frequency?

I recently just ordered several ceramic piezos used to aerosalize water and essential ...
1
vote
1answer
152 views

mosfet switching high frequency ac

I am trying to use MOSFETs to switch AC power. Here is my test circuit: simulate this circuit – Schematic created using CircuitLab If I put DC or low frequency ( < 1000khz) across the ...
1
vote
3answers
134 views

ESR of Ceramic Capacitor

I have been doing a bit research on ceramic capacitors, as I need one for the output of my synchronous buck converter. And as its very common that ESR is not straight forwardly given in the data ...
1
vote
2answers
113 views

What kind of a wire can we use for frequencies up-to 1Mhz and up?

I have been reading about wires in Wikipedia What am I doing? I am reading about wires thinking that I could by my wide knowledge with bunch of reading be capable of creating simple 8-bit or 16-bit ...
0
votes
1answer
148 views

PCB track width for MHz frequency

I am designing an DC to AC converter operating at 10MHz. Its a low power converter and the input current is under 2A. What PCB trace width should I use and can someone give me a guideline on how to ...
0
votes
1answer
59 views

Where and how do I put an inductor on a volume control

I built an stereo equalizer but I made some mistakes. As the potentiometers didn't fit on my PCB I had to put them separated and make the connections with some wires. The other mistake is that I made ...
4
votes
2answers
349 views

Amplifying a high frequency signal of 30 Mhz or above using OpAmps

I am testing a 34 Mhz amplifier in an inverting configuration with a gain of 20. The cutt-off freqeuncy of amplification stops almost at 15 Mhz , which is very low. I want it to continue up to 27 ...
17
votes
5answers
7k views

Is this true: “At over 700 Hz, current simply flows over your body”?

I have heard this in a movie clip. I was just curious to know, is this really true? Because the one thing that I do know, is that at a high voltage, the current decreases, so that it doesn't harm a ...
1
vote
2answers
256 views

Opto-coupler base connection speed influence

I am using a 4N25 opto-coupler for 5kHz to 10kHz application. In some datasheets the turn on and turn off times are mentioned to be 3us. I am wondering if this opto-coupler is suitable for my ...
0
votes
1answer
133 views

High Frequency, High Power Amplification

I was wondering if anyone could give me a little information on amplifiers. What would be the best way to amplifying a small, 1v @ 1mA, very high frequency signal (3-5MHz) to a high power signal? The ...
1
vote
1answer
44 views

Simple question on high bandwidth Opamp reproducing low frequency signals

So if one were to use a high bandwidth Opamp, at say 10GHz, and use it to reproduce a much lower frequency signal, say in 1GHz or 700MHz, would there be attenuation or degradation of the signal?? Or, ...
2
votes
3answers
88 views

Feasibility of recovering radio transmission carrier frequency

Assuming you have an FM Radio transmission at 94.4MHz where the carrier frequency is generated by a rather accurate source (lets assume allan deviation \$10^{-12}\$), is it feasible to recover a sine ...
6
votes
2answers
4k views

Trace Length Tolerance Calculation - High Speed PCB Design

I have to interface a video format converter with a ADC IC, which converters RGB analog data to digital. The connection between this ADC and Converter is a 20 bit data bus which clocks at about ...
1
vote
0answers
109 views

Very high frequency out of SPI pin in ATmega16A

I was trying to interface ATmega16A with ENC28J60, and I was facing problems with it, so I decided to physically look at the signals b/w the master µC and the Ethernet chip using an oscilloscope. But ...
3
votes
1answer
181 views

Ground plane and an impedance-controlled signal trace

I'm laying out a PCB for a project that has an HD-SDI input, which uses a 1.5GHz signal. I'm new to high-frequency considerations, so I'm struggling with a few concepts. Here is the schematic and ...
3
votes
1answer
345 views

How do I find spectral purity?

How is spectral purity measured? or evaluated? I have this signal coming from a 10 MHz crystal oscillator. I know how to calculate the SNR, but how do I calculate the spectral purity? Is it also a ...
4
votes
5answers
1k views

What components or circuitry exist that can provide extremely high speed, accurate clocks?

I've been curious for awhile now about doing some high speed projects, such as measuring time differences of radio wave reception, and was wondering if there exists components that provide clocks much ...
3
votes
1answer
332 views

Crystal oscillator problem

Here is the datasheet of the crystal (32 MHz) that I use for a MCU. The right layout is an older version of my board which totally works fine. The left one is the newer version where I placed the ...
0
votes
1answer
433 views

How do I troubleshoot this high-frequency PWM fan control circuit?

I have a 230 Volts fan from EBM papst. It is a fan that can be controlled through a PWM signal (between 1 and 10 kHz). I have built the circuit that is in the manual (see image) I did get this ...
4
votes
1answer
185 views

Capturing data at 500MHz

I have an ADC sampling at 500MHz (It is collecting data from an Ultrasound sensor). I need to be able to stream this data to my PC (for the time being - this will be done through a wireless unit). I ...