Questions tagged [high-frequency]

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

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Effect of Quality factor of elements on the resonant frequency

I want to see the effect of the series resistor on the resonant frequency that defines the quality factor of the inductor and capacitor. The resonant frequency is related to inductor and capacitor ...
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Switch Drive High-power MOSFET Trigger Module not working

Hi! I am trying to get 24V output at 5kHz frequency (square wave) from a microcontroller at the 5V-5kHz output. I am using High-power MOSFET Trigger Switch Drive Module. I connected 0V to DC- and 24V ...
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42 views

Measuring capacitance with an oscilloscope and a function generator

I was looking for a method to measure capacitance at high frequencies and found this document from Tektronix. It shows how you can measure capacitance with an oscilloscope and a function generator. I ...
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What is the purpose of this pad

What is the purpose of this pad, located between the PCB in the picture and a wifi card? It is completely enclosed in Kapton tape and there are no exposed grounds on the PCB below, on the bottom of ...
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2 answers
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Building a high-voltage, high frequency source [closed]

Can someone give an idea of how can I go about building a high voltage (20-30kV) high frequency (0-40kHz) source from a 230V, 50 Hz supply? Is it possible to convert the input 230V, 50 Hz sine ...
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Shall I add bypass capacitors on Clock inputs?

I am designing my first high-frequency (7-9 MHz) circuit for my undergrad thesis. I am aware of the use and importance of bypass capacitors on the power inputs of my ICs and how (specially for HF) ...
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1 answer
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Alternative to jumper wire for high speed evaluation board (FPGA)?

I'm working on a Frequency Response Analyzer based around an Altera/Intel FPGA. I'm using an older Cyclone V educational eval board I got for cheap from my university. The only real GPIO I can use are ...
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3 votes
3 answers
156 views

Can the addition of test points affect the quality of high-frequency signals?

I am designing a high PCB where there are some digital signals with a frequency of 100MHz. What problems will I run into if I add testpoints to those signals?
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Can you use an inductor as a capacitor for high frequencies?

Inductors behave like capacitors at high frequencies. This is of course due to the parasitic capacitance taking over. Now, would it be possible to use an inductor as a capacitor for high-frequency ...
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1 answer
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High frequency voltage divider circuit, capacitor placement to lower ESL (is this a thing?)

I have a divider circuit similar to a x10 scope probe. I need a bandwidth of least 100MHz, preferably greater. I am using through-hole MICA capacitors (1%). The capacitors have a low enough ESL that ...
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4 votes
5 answers
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UHF Colpitts Oscillator in Class C mode problem using Harmonic multiple

I want to increase the frequency of the crystal oscillator oscillating at 25MHz frequency. For this, I added an LC tank circuit to the collector in parallel with each other. I experimented to see if ...
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Electric shock through thick rubber tube filled with coolant and carrying a high voltage wire

I have two Litz wires coming out of a coil. The coil is driven with short pulses of 20 kHz sinosoidal voltage with a peak of 1.4kV. Each Litz wire is insulated by 3 thin layers of mylar sheets in ...
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1 vote
3 answers
203 views

What's the signal seeing on the output - 50 ohm?

Hi, I'm designing an OP amp circuit. I would like to terminate the output with 50 ohm because the device will be a measurement device with an oscilloscope or DUT on the iutput. Left side is basically ...
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Protection from high voltage in high frequency ignition in plasma cutting machines

I am currently in the process of designing a circuit for detection of a short circuit of a plasma cutter nozzle with material when there is no arc. The important requirement is that detection ...
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  • 123
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1 answer
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BJT High Frequency Effects?

I am studying high frequency common emitter amplifier and I came across a model where parasitic capacitances C_CB, C_BE, C_CE of BJT are included. In my textbook the small signal current gain beta of ...
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-1 votes
1 answer
112 views

How to rectify and smooth a high frequency sinewave

I'm working on an experiment that generates a high frequency sinewave using an air core transformer. How can I rectify and smoothen this high frequency sinewave because most of the high current ...
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1 vote
2 answers
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Recommended Fixture for a 10 MHz to 40 GHz S-Parameter Collection

I would like to characterize a range of SMD and TH components in order to show how different components have different parasitic elements that must be accounted for as frequency increases. I would ...
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Is it a bad idea to have a complete high frequency loop on the top plane of a PCB?

I'm designing a 6 layer HF PCB with the GND plane on the 2nd layer and a 100MHz frequency oscillator on the board, and I'm wondering if it's a bad idea to have the entire loop path of the oscillator ...
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1 answer
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High frequency model of transistor AC ground AC input

When creating the high frequency model for transistor circuits, certain capacitances arise. A lot of them are often in parallel to one another(so they add up) or grounded on both sides(so they get ...
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1 answer
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Why is mutual inductance coupling high in a microstrip PCB line?

I am learning about crosstalk on PCBs from the high-speed signal propagation book by Howard Johnson. It says mutual inductance coupling is high in microstrip lines compared to mutual capacitive ...
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6 votes
3 answers
792 views

Does the 1x oscilloscope probe setting slow down MHz digital signals?

I was debugging what I thought was a weak LVDS driver fed with a 10MHz clock for hours when, out of other options, I've set my scope probes to x10 and although the signals were showing some ringing ...
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2 votes
1 answer
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Testing of HF transformer designed for phase shift full bridge converter(PSFB)

I have designed an HF transformer for a PSFB converter. Specs: Peak Primary Voltage = 800 V Peak Secondary Voltage = 176 V Turns ratio Np:Ns = 18:4 Primary Irms current = 12.38 A Secondary rms ...
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2 votes
1 answer
88 views

Book to understand BJT non-linearity [closed]

Can someone please suggest a good book to understand low and high frequency non-linearities like beta, gm, cbe, cbc and rb present in bjt. Thanks
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0 answers
77 views

How to manipulate timer registers of Arduino Uno?

I already asked about How to achieve high speed microstepping? I even used Arduino Due to achieve high speed. Practically there was no difference compared to Uno but by changing baud rate I could see ...
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  • 135
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4 answers
174 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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3 answers
190 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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  • 179
1 vote
2 answers
164 views

High-frequency voltage conversion (3.3V control of Neopixels)

I have repeatedly heard that control of Neopixel LEDs running at 5v requires special voltage conversion when using a 3.3v processor, as the 3.3v control input is actually out of spec for the WS2812B ...
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0 answers
61 views

I can't switch on both coils in double arc lighter transformer

I was trying to make DIY plasma lighter (and kind of made it too) but I can't figure out something. The transformer has 2 primary and 2 secondary coils so I made a NE555 signal generator with 36 kHz ...
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-2 votes
1 answer
200 views

Choosing an opamp for the amplifier stage of a signal generator (uses AD9833) [closed]

I am currently on a project to make my own signal generator for use in testing circuits etc. I have based it largely on a tutorial here: https://www.allaboutcircuits.com/projects/how-to-DIY-waveform-...
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3 votes
2 answers
380 views

RF PCB ground plane surface finish

I am designing two boards that are supposed to operate at frequencies 2.45GHz and 5.8GHz. In my design, I use simple microstrip lines (not coplanar) on FR4 substrate. There are some quarter-wave ...
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2 votes
2 answers
451 views

Why are transmission lines and waveguides needed for high frequency?

At low frequency, we can just use a piece of wire to connect electrical components, but why are special transmission lines and waveguides needed for high frequency circuits? Also I am confused by the ...
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2 answers
102 views

Best diode for very high frequency (Vacuum?)

If we look at what's commercially available, the diodes with the highest maximum frequencies I can find are in the low GHz range, of the Schottky type. I can also find research papers detailing ...
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1 vote
1 answer
129 views

Converting 5V Square-Wave to +-5V Square-Wave

I am a student electronic engineer and was hoping to get some guidance on a project that I am working on. I am using the AD9850 module to output a 5V square-wave at 1.1MHz as can be seen in the figure ...
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0 votes
3 answers
158 views

LTspice anomaly with pico-Farad capacitors - minimum 20µs rise-time?

Why is it, if a 28800pF (28.8nF) ideal capacitor and 4Ω resistor are in series with a voltage source, that source rises linearly to exactly t=20µs? For C=2880pF, I expect \$5\tau=2880\text{pF}\cdot4\...
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0 votes
2 answers
215 views

How do I add a DC offset to my RF signal for a 50 Ohm Device?

I'm working with a system that requires a ~250-400 MHz modulation signal from 0 to 1.5 V (or -1.5 to 0 V) on an electro-optic modulator (EOM, Jenoptik AM635). I have a signal generator capable of ...
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  • 1
0 votes
1 answer
36 views

RF Cavity resonance based on E field

Is it true that the resonant frequency of a pillbox type RF cavity is dependent on the E field and the cavity's geometry size, because for each frequency there is only one size/radius corresponding to ...
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1 vote
3 answers
116 views

PMOSFET driver not pulling gate voltage up to supply

I just started learning about MOSFETs and gate drivers and the like. I wanted to make an H-bridge operating at 320kHz that can later be modified through the use of faster FETs to get up to ~10MHz. I ...
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1 vote
1 answer
148 views

Corrugated tracks in PCB [duplicate]

I've noticed that on some PCBs, there are some undulating tracks. An example can be seen on the Compute Module IO for Raspberry Pi Compute Module 4 (CM4). Apparently, these are high frequency tracks. ...
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0 votes
3 answers
179 views

How is this high pass filter?

I am new to electronics. I am watching this video. At 5:48, you can see the high pass filter: I understand the high pass filter, look at this: Then, I thought the first circuit should be like this: ...
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  • 449
0 votes
1 answer
111 views

How does this circuit generate a high frequency signal?

I am new to electronics. I am watching this video. At 5:37, you can see the first half of the circuit generate a high frequency signal. How do an op-amp, 9 VDC, and a few resistors generate a high ...
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  • 449
1 vote
1 answer
91 views

Gate drive transformer troubleshoot

Recently I've been working on a half-bridge solid state tesla coil project. After doing some research, I came across a lot of universal tesla coil driver schematics, and I've realised that a lot of ...
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0 votes
2 answers
58 views

What rise time should pulse have to have desired pulse width [closed]

I have a question regarding my high speed laser driver. I want to have 10ns width pulse. What rise/fall time I would need to have that I can say I still have 10ns pulse. Is there any percentage that ...
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0 votes
1 answer
91 views

How does relative permittivity change at high frequency?

I am trying to design RF radar optics for 60GHz. However, I do not know how 'constant' the relative permittivity of a substance is. One material I am making an RF lens out of is PEEK which measures ...
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8 votes
1 answer
174 views

Backwards compatibility of PCIe AC coupling capacitors

The PCIe base spec mentions that platforms operating only at 2.5GT/s or 5GT/s may use AC coupling capacitors in the 75nF-265nF and that platforms supporting 8GT/s and above must use 176nF-265nF. ...
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0 votes
0 answers
111 views

Response of mosfet in high frequency

I used two mosfets to control current passing through resistance 5ohm, shown in the circuit of the attached file. The simulation results show that the mosfet switching frequency higher than 10KHz ...
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9 votes
5 answers
1k views

How to calculate values for decoupling capacitors

For decoupling we just use a capacitor like 1 uF bulk and 0.1 uF ceramic caps at each power pin. But how are these values calculated? How many caps do we need to use in parallel? Can anyone explain it ...
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1 vote
1 answer
150 views

Why there is capacitor in series in high speed designs like SGMII?

Why we are connecting capacitor in series in high speed designs like SGMII. If it is to remove DC voltages, why we are not using on other signals like I2C, SPI and so on. What is the major purpose. ...
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  • 405
1 vote
0 answers
71 views

High frequency AC power supply

I'm looking for methods to deliver a alternating current of 5 A at variable frequencies 0-20 kHz to an electromagnets to generate an alternating magnetic field. I've been reading various post and ...
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0 votes
1 answer
133 views

Cut Off Frequency in the Frequency Response of RC circuit

In the frequency response curve of RC circuit, why does the curve falls rapidly after the breakpoint? It approximates to a certain amplitude upto the breakpoint. In the diagram, given below, it is ...
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0 votes
1 answer
58 views

Can you route multiple returns to the same via?

New to PCB Design and layout. While routing bypass caps, I instinctively give each bypass cap its own via to the ground plane. What would be the disadvantages of having two (or more) bypass caps share ...
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