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

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1
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5answers
473 views

Very high speed counter (around 1.5 GHz to 2 GHz)

I am thinking of a device that can measure the distance of an object from a sensor using a radio transmitter and receiver pair. I'm thinking of using a counter at the sensor side, with a ...
-1
votes
0answers
65 views

Modifying AM radio to receive CB/CW/HF 27Mhz signal [closed]

I'm working on a project that calls for pre-used radios to be modified to detect an AM CB radio broadcast. I've never done any work with radios before, and have been trying to hunt down any sort of ...
0
votes
0answers
14 views

Noise in Inductor Current : Buck Converter [duplicate]

Source DC: 300v DC Output DC required : 160v DC Load Current : 7A DC Buck Converter Topology : IGBT as switch @ 8khz 1.1 mH Ferrite Core Inductor Measured Inductor Current ...
0
votes
3answers
51 views

Capacitor on line with high frequency digital signal?

Capacitors act as a short for high frequency signals. If I place a capacitor on a digital 5V PWM line or perhaps a motor encoder line does the cap still act as a short to ground for the square wave ...
2
votes
1answer
151 views

What does this capacitor do? (Microwave biasing circuit)

I'm wondering what \$C_B\$ attached to the bottom of \$R_{C2}\$ does. This is a screenshot from a textbook called RF Circuit Design: Theory and Applications by R. Ludwig And P. Bretchko. Looking at ...
0
votes
2answers
105 views

Can I amplify high frequency signal?

I have found this awesome Raspberry PI FM transmitter project. It uses RPi GPIO pin to simulate FM signal. After some filtering to smoothen it, this could act like a real transmitter. But at this ...
0
votes
1answer
58 views

Why do we use S-parameters for High frequency signals?

I have read at numerous places that S-parameters are used for analyzing systems which deal with high frequency. But why only high frequency? From what I have read, I have understood the following ...
18
votes
4answers
528 views

At what frequencies does PCB design get tricky?

I have designed many mixed-signal PCB's where the highest-frequency component is the microcontroller's crystal oscillator itself. I understand the standard best practices: short traces, ground ...
3
votes
1answer
214 views

Metcal: why do they heat with HF?

I got a used Metcal station from ebay for my home-lab and everything I read about soldering with it is right, it is a completely different feeling. I understood that stuff about controling the ...
5
votes
5answers
187 views

Which parameters in datasheet give information about a BJT's step response quality?

I did a test with randomly chosen 12 NPN BJTs. I applied a clock pulse to each of them and observed their collector voltages. Some of them showed very low rise time, while some responded terribly ...
0
votes
2answers
84 views

How do plasma lamps work? [closed]

I've been trying to understand how plasma lamps (or plasma globes, according to Wikipedia) work and why you don't die a horrible fiery death when you touch them. What I've got so far is that the ...
3
votes
1answer
143 views

Definition and Explanation of Insertion Loss and Return Loss

I'm trying to understand the physical meaning on Insertion Loss and Return Loss on a transformer, specifically RF transformers. The values are often quoted as figures of merit in datasheets, but I'm ...
0
votes
1answer
107 views

Where to salvage inductors?

I need a toroidal inductor for my ZVS flyback driver. The value should be between 47uH to 200uH. It should be able to handle 6A. Where can I salvage them from?
2
votes
3answers
149 views

NE555 Flyback Driver MOSFET failiure

simulate this circuit – Schematic created using CircuitLab I made this simple NE555 Flyback driver. I used a 9V Battery to power the NE555 and a 24V 6A power supply to power the flyback. ...
1
vote
2answers
81 views

How to amplify a 2MHz signal?

I am working on ultrasound sensors. At the receiving end I have a 2MHz signal of 80mV p-p. I need to amplify it at least by 10 times. Please suggest an appropriate method. Additionally, I need to ...
0
votes
0answers
28 views

Minimum Distance for Corner Reflector

In RF-Measurements Trihedral corner refelctors are often used as calibration targets because of their constant and analytically defined radar cross section. The RCS of a trihedral corner reflector ...
4
votes
2answers
194 views

Why does more bandwidth mean higher bit rate in digital transmission?

I understand that similar questions like this one have been asked before on this site, listed below. However, I am confused about the answers. If I explain what I think I understand, can somebody ...
2
votes
2answers
143 views

Minimal distortion in transmission line

In a transmission line, the condition for minimal distortion (caused by the line) are when (R/L = G/C) in the line, right? However, I don't see any reference to that in any application notes or ...
0
votes
1answer
107 views

IC555 flyback driver troubleshooting

I made a flyback driver which just uses an astable 555 circuit to drive the flyback. The 4 and the 8 pins were connected to the positive rail. 7 pin was connected to the positive rail via a 1K ...
4
votes
1answer
105 views

How can I track where this 471kHz noise is coming from?

I'm new to EE in general and I just received my first oscilloscope (Rigol DS1102E). Anyway, I'm building an audio circuit using an Arduino Micro and the infamous ...
0
votes
1answer
180 views

How to make prototype circuits that include microcontrollers, and avoid breadboard annoyances at high frequencies?

From my searches of the web ( as well as this question ), I have found that breadboards - like the one on picture - aren't a good idea when your application involves high frequencies. I am going to ...
8
votes
1answer
171 views

How to design a 1-500MHz sine wave level detector to -90dBm?

I want to build a sine wave level detector that works for a single 1-500MHz sine wave in the range of -40dBm to -90dBm. This is a hobby project - so cost is not a big obstacle :-), but I want to stay ...
23
votes
2answers
2k views

Can anyone explain this high-frequency “alien voodoo black magic”?

I was casually watching Mike tear down a spectrum analyser (13:30 is the relevant part, 16:50 is the awesome part), and he came across what he aptly described as "weird messed up alien voodoo black ...
6
votes
2answers
260 views

How does an increase in operating frequency result in decrease in the size of an inverter circuit?

I was reading about inverters in a textbook where the author says that The size and cost of the circuit can be reduced to some extent if the operating frequency is increased but then inverter ...
1
vote
2answers
117 views

Describe qualitatively the amount of current passing through resistor if the source oscillated at low frequency?

I am stuck on lab question 3. I do not know how to determine the current crossing the resistor for oscillating current at varying frequencies. Help is greatly appreciated
2
votes
1answer
79 views

Looking for High Speed Parallel DAC IC without data latch

I have designed a FPGA based DDS that creates digital signals between 0-70MHz. Now I want to convert my digital data into analog. As the base frequency is 200MHz, I need a high performance parallel ...
2
votes
1answer
103 views

High voltage, high frequency, pulser

For a rather unusual application, I need to generate high voltage (>500V) pulses with a very short rise time (10-100ps). Is there something that can do this off-the-shelf? Assume money is no object. ...
0
votes
1answer
148 views

Confusion regarding considering a transmission line as lumped or distributed

I am just elaborating my question. I have came across different formula's to say whether a Transmission line is lumped or distributed. in one of the books i read " Effective length of a electrical ...
3
votes
2answers
137 views

USB Full Speed driver with MCU in DIP package

I desire to apply a USB driver with a MCU that has a DIP package. The device should communicate in Full Speed (12 Mbps). To your experience, is that possible? Taking into consideration the physical ...
3
votes
1answer
92 views

What concerns are there with running high frequency traces?

I am working on a project where i will be laying out some traces that will be handling Gigabit Ethernet traffic. I know that putting these traces on the outside layers (Top or Bottom) is a bad idea, ...
6
votes
1answer
225 views

Running JTAG chain over busy backplane

We are busy designing a large system with around four PCBs slotting into a backplane. Each PCB could contain a DSP as well as a large FPGA. We would like to run 2 JTAG chains through the system, one ...
-4
votes
1answer
257 views

What kind of waves can penetrate walls/floors and cause tingling, headache, nausea, etc? [closed]

What types of waves would be able to penetrate walls and floors and at high frequency or intensity would cause symptoms like tingling or burning skin, headache, nausea, and heart palpitations? I know ...
9
votes
1answer
727 views

What, if anything, makes shielded loop antennas so great at rejecting local noise?

There is a folk wisdom, among amateur radio operators, that if you have a lot of noise on HF, such as in an urban location, then using a shielded magnetic loop antenna for receiving is really great ...
1
vote
2answers
209 views

How does this circuit multiplex an antenna between a transmitter and receiver?

I've built a Softrock RXTX kit (full schematic: pdf gif, see lower-left corner). It has one connector for one antenna used for both receive and transmit, but I don't fully understand (likely due to my ...
3
votes
2answers
337 views

Ground vias on high speed PCBs

I know that if I use vias on high speed traces that I need to reduce the inductance effect of the via. So I will put ground vias next to these vias to help returning current. I have seen a picture ...
1
vote
1answer
200 views

Why cable TV frequency range ends at 1 GHz?

Currently frequencies 50-1000 MHz are allocated for TV and data transfers. I understand why there are limitations for aerial or satellite transmissions, but why are they retained for cable ...
2
votes
1answer
120 views

Filtering High Frequency Channel Noise

I have a signal that should have this theoretical shape: The signal I am receiving experimentally has the following shape: And here is a plot that better shows the shape of the waveform (I have ...
4
votes
3answers
278 views

Reduce and clip voltage of a 5Mhz ultrasonic signal from +-50V to 0-3.3 V

I know there are a lot of posts similar to this one but some differences make it worth posting it. I’m working on a project where I have a 5MHz AC signal with the largest amplitude of +-50V. It’s an ...
1
vote
4answers
151 views

sub-kilohertz channel spacing with PLL

So I'm trying to use one of Analog's evaluation board PLL circuits (ADF4350, here). I need to generate frequencies around 1 GHz, ideally in a +/- 250 MHz range, but in steps of < 1 KHz. Using the ...
0
votes
1answer
139 views

Poor RF communications : looking for advices [closed]

I am in charge of a temperature monitoring and controlling project in a new building with 7 floors and 14 rooms by floor. I installed last week thermostats devices in each rooms permitting to send ...
3
votes
1answer
100 views

Name for circuit with multiple paths with aim of reducing inductance

Trying to find the best way of describing a circuit that uses multiple separate physical paths to reduce effect of inductance on by HF signals. Is there a term for such?
2
votes
1answer
495 views

Why high voltage from TV flyback shocks you without the need to complete a circuit?

Assuming the TV is plugged into an isolation transformer (although I think there is already a small transformer onboard), then ground is not part of the secondary side. Yet, high voltage from flyback ...
1
vote
2answers
125 views

10A power suply, high frequency

An EL wire consume ~10mA/m, and need a 1800Hz, close to main voltage, sinusoid supply. (The noise is not a matter as the EL wire itself will cut off the frequency >2kHz). for an installation I would ...
0
votes
3answers
639 views

Measuring high frequency current with Adrunio

Is there a way to measure the current of a high frequency signal (100Khz) with an Ardunio? I am thinking that some form of analog circuit could be made whose input takes AC current and whose output is ...
2
votes
1answer
301 views

How can I superimpose Pulse signal

I designed this circuit, put V1 as sinusoidal source and output was good at oscilloscope.However when I changed V1 to pulse signal there was no output on oscilloscope. Thanks to tell me if pulse ...
5
votes
3answers
635 views

How is a transformer working at 10's of MHz designed?

In this answer a switching power supply using a transformer operating at 10's of MHz range to reduce size is mentioned. How would such transformer be designed? Would it still have a plain old design ...
0
votes
1answer
325 views

Connect SMA to a regular pin/wire

I have an RF signal (5ns pulses every 200ns) coming out from a SMA connector on FPGA board (Spartan 3E Starter Kit). I want to send this signal back to the FPGA using one of the on-board pins. So, I ...
1
vote
3answers
172 views

Ultra high bandwidth serial data stream

I have a ultra high bandwidth data stream (USB 2.0 Highspeed), on which I need to add an header for synchronization. This needs to be done, since the datastream needs to be transmitted wireless on a ...
1
vote
2answers
418 views

How does this circuit attenuate high frequencies?

I understand that this circuit could be used as a treble control circuit with high frequency gain occuring when R3 is set so a=b (we'll call this k=0), and high frequency attenuation occuring when R3 ...
3
votes
2answers
352 views

How to test RF (1GHz) PCBs?

I have a number of RF PCBs. I would like to test these PCBs, so can someone guide me as to how to test these PCBs. The list of the PCBs that I want to test is mentioned below. 4th order Butterworth ...