# Questions tagged [high-frequency]

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

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### Return current on PCB

As PCB designers we all know that for high frequency signal (MHz), we should design return path (reference GND plane) underneath the signal as follows: https://www.allaboutcircuits.com/technical-...
• 115
93 views

### High magnetic permeability material at 100MHz

I'm doing experiments as a hobby and was trying to find a material with good (very good) magnetic permeability at least at 100 MHz (higher frequencies are even better). Ideally the material would have ...
• 93
1 vote
55 views

### Cable current rating for high frequency applications

I am looking for power cables for high-speed motors, with frequencies up to 700Hz. All the tables that I find online are referred to 50/60Hz applications. I am not able to find derating factors ...
39 views

### What is minimum gain crossover frequency in bode analysis?

I know gain crossover frequency at which magnitude of open loop transfer function is 0. But what is the case here for minimum Wgc?
104 views

### How to create a frequency-dependent device with low losses at 50/60 Hz and high losses at 100 kHz

I'm working on a device to dampen high-frequency transients. Here are the specifications: Rated current: 30 A RMS Losses at low frequency (50/60 Hz): <10 W (required steady-state condition) Losses ...
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### Switching circuit with logic 3.3V control on p-channel JFET

The task is to derive sinewave (of higher frequency) chopped by step-function (also periodic but of lower frequency, i.e. several periods of sine wave are placed in that pulse). So I have a sinewave ...
88 views

### Why is the core resistance modeled as 2*Rp and capacitance as Cp/2 in a common-mode choke?

I directed my attention to a paper regarding the modeling of common-mode chokes. Within this paper, the authors structured the circuit in such a manner that they designated the core resistance (...
• 101
73 views

### How to achieve 50 Ohm Impedance with a SMB connector

I have a PCB design with a SMB connector but can't find any information about how I should treat the pad to ensure 50R impedance. Should there be a keepout on the ground layer directly beneath this ...
• 55
344 views

### Sine oscillator at extremely high frequencies

I would like to make a "good" (doesn't need to be perfect) sine wave oscillator from 50 GHz to 1 THz, if possible with two outputs: one is $\sin(2 \pi f t)$, the other one would be \\$\cos(...
• 93
94 views

### 4 MHz RF-receiver not working

I have been trying to make a 4 MHz receiver, to receive a ASK/OOK modulated signal but it never really works. I have my suspicions that it's the LC tank that is not tuned correctly, I am quite new to ...
134 views

### Intuitive explanation of open stub behaviour

Can someone please give me an intuitive explanation of open stubs? I have the length-based mathematical derivation and explanation from my textbook, but I am looking for an intuitive one. For example,...
85 views

### What are the Best Methods for Creating Pulsed DC or AC Current at 2.4 - 2.5 GHz Frequency Range?

Some of you may be aware that UFOs are sometimes recorded emitting microwave radiation. I think they might be using an electromagnetic coil that is being pulsed with DC current or is using AC current ...
48 views

### Purpose of Carrier Detect (CD) pin in RF modules

I have a RX2-433-160-3V receiver module from Radiometrix. I wanted to know what the purpose of the CD pin is. I have read the datasheet but don't really understand what it's meant to do. The datasheet ...
137 views

### How to get megahertz frequency with a 555?

I need to produce a 1.7 MHz signal. Up to around 200 kHz the 555 IC and my simple astable circuit are working just fine as expected, but when I decrease R1 and R2 to less than 100 Ω the frequency ...
217 views

### Does inductance in a resistor matter if it is used as a bleeder resistor?

I am designing a Marx generator and I want to place a bleeder resistor across each capacitor in every stage of the Marx gen. I have been looking at using low cost RI80 resistors from eBay. Each stage ...
122 views

### BJT Zero-Crossing Detector for 40kHz Ultrasonic Signal - Distortion & Receiver Issues

General Information About the Project I am trying to design a zero-crossing detector circuit for convert the sinusoidal signal from an ultrasonic transducer to a square wave. Here is the image of ...
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107 views

### Can I make a high frequency DC-DC SPMS boost converter with an SiC MOSFET?

I am trying to design a boost converter. The specifications are: Vin = 100 V Vout = 200 V Iout = 1 A Fsw = 5MHz duty cycle = 50% I tried with LTspice but some new parts do not have models, so the ...
1 vote
60 views

### Arc Lighter: Relationship between transformer inductance, oscillating frequency and energy of the spark

I'm building an arc lighter using YouTube videos as a reference. This circuit from GreatScott worked for me. I'm now trying to understand the relationship between the transformer inductance and ...
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233 views

### Problem with push pull output

Well, I'm working on an oscillator topology to excite a piezoelectric device that works at high voltages. For this I have a high frequency signal generation stage followed by a push pull amplifier to ...
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1 vote
115 views

### Problems with high frequency SPI

I have what I can best describe as an ASIC (TI's DLPC3420 digital micromirror device controller) communicating with an SPI flash (MX25L1606E). It first reads a part of the flash at low frequency of ...
• 888
73 views

### How to amplify ultra high-frequency signal

I have found some schematics to amplify ≈100 MHz signal, but can't find a schematic for 2.4 GHz and higher, up to 5+ GHz. The main problem I face is that I can't find a transistor fast and powerful ...
167 views

### How to create high frequency signal? [closed]

The question arose because I could not find a comprehensive answer, even though frequencies such as 2.4 and 5+ GHz are pretty common (bluetooth, modems, RC toys, etc.). So far, what I know is: There ...
98 views

### Understanding inductance and its dependency with frequency

I am trying to understand how to design an inductor that has constant parameters over a wide range of frequencies. Especially over high frequencies because I want to use them for impulse testing ...
• 334
68 views

### Sensor for low-amplitude, fast current pulse?

I am trying to find a way to measure low-amplitude, fast current pulses in wires ranging from ~1-5 mm in diameter, preferably using a non-contact method. The current pulses are typically around 50 mA ...
• 123
436 views

### Downside/tradeoffs to clamping signals with zener diodes

I have a signal source that sends fast pulsing square waves in the MHz range (encoder pulses from a motor) down a long transmission line to a receiver. I have tried many solutions and different types ...
127 views

I have a problem understanding the circuit below where the LC oscillator is used to produce the negative cycle wave for the amplitude modulation. I am having a difficulty in grasping the fact that the ...
• 593
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### Resistor in high frequency

Can we use a simple resistor of any kind, with resistance of 1.2 kΩ in high frequency like 4 GHz?
2k views

### How are RF filters constructed?

I want to know what filter circuits look like in the RF (MHz-GHz) frequency range. Are they just like low frequency LC filters, but with appropriately adjusted component values? For example the VLF-80+...
86 views

### Filtering spikes in electric fence energizer

I have designed a 12V electric fence energizer. It works as follows: A flyback converter charges a 50uF capacitor to 400V. After the capacitor has been successfully charged, a thyristor discharges the ...
1 vote
120 views

### Converting a fast-switching 0-2.5V input to TTL signal

Dear fellow engineers, I am attemping to convert a fast switching (~ns) 0V - 2.5V pulse from FPGA into a TTL-standard (0V - 5V) signal. I have been browsing for voltage regulators online. Most of them ...
93 views

### How to switch a 200 Vpp AC signal @ 2000 Hz in under 1 millisecond?

I want to switch a ~120 V AC signal with a frequency of up to 2000 Hz. For my application (driving electrolumnescent wire) it is important that the switching duration is not higher than about one ...
145 views

### Why is the frequency response from my 1X and 10X probe seem to be converging with increasing frequency?

I'm a Mechanical Engineer trying to get into electronics so please excuse my lack of understanding. I'm feeding a 5.0 Vpp sine wave into my SDS 1202X-E scope from my signal generator (see image below)....
48 views

### What is the key circuitry in a form of high frequency signal generator that means power would be sent and reflected when there's an open load

Ive asked enough questions to explain why when there is an impedance mismatch there is power reflected which from my understanding is because there is a reflection of the waves, and also the cause of ...
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### On-chip Co-planar Waveguide Design on Si – SiO2 Substrate

I want to design, simulate, and fabricate on-chip Coplanar waveguides (no bottom ground) on a Silicon Dioxide layer 5um thick on a Silicon 500um thick wafer. The metal electrodes will be 1um thick ...
17 views

### Debugging PLL STW81200TR not locking

I need a bit of debugging help with SWT81200 PLL that I am using on my custom designed PCB. I am able to configure registers through SPI communication, but the problem is that I am not able to achieve ...
174 views

### What is the purpose of this long capacitor/inductor chain on a DDS IC evaluation board?

Image of the B output stage of the EVAL-CN0304 AD9834 DDS Evaluation Board IOUT_B is a current source, not potential source, so the initial say half of the circuit I get. The resistor gives us a ...
1 vote
44 views

### How to provide a low response time <1µs constant current source up to 1.5A

I need to provide a constant current source that can provide up to 1.5A current and a compliant voltage of 0-40V, with a low response time of <1µs. How should I approach this problem? Common bench ...
200 views

### Measuring a 10-30 ns pulse width

For my school project over summer holidays I was tasked to measure a 10-30 ns impulse of a laser. So far I got the impulse on the oscilloscope, which I will run through a Schmitt-Trigger to get a ...
• 1
101 views

### Why can’t I find fast transistors and same fast diodes?

I am trying to make a 30 GHz 32 (or 64 bit) counter on flip flops. Ready counters do not satisfy me due to max frequency and price, so I decided to make it on my own from flip-flops. Ready flip-flops ...
• 267
110 views

### High swing (Low-voltage) cascode current mirror pole

I have been trying to figure out extracting the exact derivation for the poles, I am only struggling with figuring how the author got pole 8. I am using the small signal for the high swing cascode ...
79 views

### Part guidance: Switching 120 VAC @ 3 kHz in < 5 ms

I want to control electroluminescent wire, which runs at 100 Volts AC @ 1000 to 3000 Hz, with a desired switching delay of under 5 ms. I have used Sparkfuns products in the past, but they are no ...
73 views

### Which of the modern transistors could be a substitute for 2N709?

I need to replace the damaged Q1 transistor, but I don't have a 2N709. I was thinking about 2N2222 because of the similar case type. However, this transistor differs in frequency. In this follower ...
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1 vote
68 views

### How to simulate a Large Structure at low frequency in CST Microwave Studio?

In CST Microwave Studio, I attempted to simulate a large (215x30cm) loop structure at 1kHz. However, CST gives a warning of 'too large' mesh size. The mesh size increases up to 6 Billion, however, if ...
101 views

### High frequency voltage to current

I have a signal oscillating at tens or hundreds of MHz (up to 200 MHz expected), with 2.5 V mean and approx 200 mV peak to peak. I'd like to produce a current proportional to this signal at approx 40-...
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1 vote
71 views

### Trigger (Flip-flop) with under 3 ns delay?

I want to make nanosecond clock timer as a 64-bit counter. There is a scheme (4-bit): I am trying to find JK-trigger, or other, that can work with 300 Mhz clock speed, at least, i.e. 3.3 ns at most, ...
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### Calibrating the R&S FPL 1003 Spectrum Analyzer

I am setting up an EMC test bench and I have a spectrum analyzer(SA): The Rohde and Schwarz FPL 1003 Spectrum Analyzer. I am trying to conduct some preliminary tests to ensure that the results seen on ...
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### Shielded -vs- Non-Shielded, running CAN Data Cable w/ 115/200VAC 3-Phase @ 400Hz

*Edited, AGAIN, in an attempt to remove any confusion Settle this debate! I am designing a Harness for testing the functionality of a PDU (Power Drive Unit), operated using CAN (ARINC-825). Prior to ...
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### Ways to get around amplification limited by op amp GBW?

I'm working on a project that requires me to amplify 70 pA to read out at 10 V (the digitizer I'm using to collect data has a range of 0 to 10 V readout). On top of this, I need to sample my voltage ...