This tag marks questions related high frequency (radio) circuits.
3
votes
2answers
108 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
120 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 ...
0
votes
0answers
36 views
Are there off-the-shelf sources for high-frequency high-current magnetics?
I'm often looking for high-frequency chokes. My typical spec ranges are 500-1000 volts, 10-40 kHz, 5-200 amps. Off-the-shelf chokes in that range are almost non-existent from what I've seen. The ...
2
votes
1answer
89 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
152 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
88 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
88 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
89 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
210 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
112 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
279 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
188 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
297 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
189 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
153 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
260 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 ...
2
votes
2answers
213 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 ...
2
votes
1answer
188 views
Signal reflections at the driver?
This question is related to How do I use directional couplers on a differential signal?
I understand that if I have an impedance mismatch at the end of a signal cable, E.G. from a terminator which ...
2
votes
2answers
274 views
How do I use directional couplers on a differential signal?
I understand how a directional coupler can be used to measure signals travelling in one direction on a wire. What I don't understand is exactly how this would work on a differential signal, E.G. LVDS ...
0
votes
2answers
224 views
380-385 Mhz band-pass filter (SAW?) [closed]
I am relatively new to the world of electronic components, but I've been trying to learn for a while now and I understand most of the logic behind simpler designs.
Now I'm trying to build a filter.
...
2
votes
1answer
199 views
What makes an active probe so expensive?
This question probably has a similar answer to Why are digital oscilloscopes still so expensive?. But why are active oscilloscope probes so expensive? I mean, they're hundreds, if not thousands of ...
10
votes
4answers
1k views
Is this a good design & layout of an active differential 'scope probe?
This question is an extension of Homebrew differential 'scope probe. I thought I should make this a new question though.
I need to measure a 100Mb/s LVDS signal to check its integrity. I will try to ...
10
votes
6answers
2k views
Crazy homebrew 500 MHz 1 Gs/s oscilloscope possible?
I was reading USB scope probe - request for comments and ideas, and it got me thinking. What I'd really like is a very high performance oscilloscope, one which would cost $10000 or so. Surely many ...
4
votes
2answers
197 views
Does a 250MHz FIFO chip exist?
If I have 8-bit parallel data being clocked out of a chip at 250MHz, is there some way I can buffer it? I only need to store about 1kB. Preferably this would be a FIFO. Does such a fast FIFO exist at ...
6
votes
1answer
676 views
Homebrew differential 'scope probe
I may be able to get my hands on an old 600MHz LeCroy oscilloscope. However, it doesn't have any probes.
Is it feasible to make an active differential probe for it using a high-speed op-amp, like the ...
4
votes
4answers
563 views
How important is it to put decoupling caps on the same side of the PCB?
How important is it to have decoupling capacitors on the same side of the PCB as the IC? I am desperately short of space in a design, and it would really help to put the caps on the bottom side.
I ...
2
votes
2answers
778 views
H-bridge ic for high voltage and/or current
I tend to design my circuits around H-bridges, but the problem with making them out of standard mosfets is that I always have to compare the rise times, fall times, threshold voltage, etc of my ...
0
votes
1answer
189 views
MOSFET in high frequency applications
I've heard that MOSFETs for high frequency circuits are generally configured as common gate.
Can anyone explain why? Could this be related with the internal MOS capacity?
1
vote
4answers
840 views
Clock generation using FPGA
I am trying to use Spartan 3E kit to generate 50 MHz clock. The kit comes along with a 50 MHz crystal which I am trying to use.
So, I wrote a simple code to output the clock from the FPGA to the SMA ...
0
votes
1answer
421 views
How to output signal though SMA connector in Spartan 3E Starter Kit
I want to output a signal through the SMA connector available on the Spartan 3E starter kit board. Can someone guide me as to how to do it?
2
votes
4answers
354 views
What's the Actual Speed in GHz of RapidIO or RocketIO serial interfaces?
When reading about high speed serial interfaces like RapidIO or RocketIO, I find data rates of 3.125 Gigabits/second and more.
My question is: 3.125 Gb/s = ?? GHz
What's the relation between Data ...
3
votes
1answer
172 views
Can signal quality be affected by high temp?
I would like to know if UHF signal quality can be affected by hot weather? And which of UHF and VHF is better on that case of weather ?
2
votes
4answers
233 views
Are vacuums tubes suitable for switching high current (~30amps) at high frequencies (~K-Mhz)?
I was looking to build a system for high currents (say ~30 amps) and a friend suggested vacuum tubes. In theory, vacuum tubes seemed more robust for high current applications, but after looking ...
4
votes
1answer
304 views
Generate a 4.25 GHz using 50 MHz crystal/oscillator and PLL
I want to generate a 4.25 GHz using a PLL and 50 MHz crystal/oscillator.
I am confused as to what I need to look for in a PLL. In a integer-N PLL, the prescalers are 16/17, 32/33, 64/65, etc. So, my ...
10
votes
3answers
2k views
Why does an inductor behave as a capacitor at high frequencies?
In truth, I've only been told this anecdotally by an instructor, but can someone explain the physics at play?
I have been told that if an inductor is driven at a high enough frequency, it will begin ...
1
vote
1answer
358 views
How to generate a high-frequency clock?
I want to generate a high frequency (4.25 GHz) clock for a high frequency communication circuit. So, my question is:
What are the alternate ways of generating the high frequency clock and which would ...
2
votes
1answer
273 views
Opamp input impedance on high frequency
I have so far used opamps for near-DC work (connecting transducers to AD and the like) and have not studied electronics in school. Now i made voltage follower based on classic LF412.
When i passed ...
1
vote
4answers
461 views
Measuring low current at very high speed
I have a circuit with a very-low-power Jennic JN5148 module with microcontroller and 2.4 GHz radio, and some low-power sensors.
I have to measure the supply current of all these components, in an ...
3
votes
1answer
305 views
Can someone break down how this receiver works?
I'm having difficulty understand how this receiver works due to its size. It was taken from this site: http://jap.hu/electronic/rf.html. It is on top labled toy car receiver.
The toy car transmitter ...
0
votes
0answers
86 views
Smart Meter output reading [closed]
What type of meter must you use to read the frequency and power output of a smart meter? Also what is the best source for buying an economical
8
votes
3answers
840 views
Need an XOR gate that works up to 2 to 3 GHz
I have encountered an unusual situation in which I require an XOR gate that will function reliably when presented with a square wave input with a frequency between 2 and 3 GHz. I know that desktop ...
7
votes
2answers
236 views
Litz wire & skin effect
Why do we need isolated wires to get litz wire?
Doesn't usual multi-wire cable have same effect (probably less effective) due to air gaps between non-isolated individual wires?
I.e. shouldn't ...
2
votes
2answers
110 views
100Ω and High-speed data lines
I just had a problem with some lines coming from a PIC IO bank, and going into the base of a transistor (BC635) at some high speed.
Without any base protection (since the PIC can't provide enough ...
5
votes
2answers
502 views
2
votes
4answers
291 views
Ringing on my OSD project
I'm developing a fully graphical on screen display (OSD) for RC aircraft and other RC things. The project is almost complete, with a working prototype and PCBs made. The OSD is based around a dsPIC33F ...
2
votes
4answers
288 views
High voltage high bandwidth analog mux
Does anyone know some ref of high voltage high bandwidth analog multiplexer? I am looking for a mux that can tolerate input voltages up to 10V, but has also a high bandwidth of at least 1Ghz. I am not ...
4
votes
4answers
691 views
8
votes
3answers
541 views
What to think about when designing HF PCB's?
I am currently designing a small PCB in Eagle Cad that has a GPS 1PPS signal (one short pulse per second) as input. The pulsetime for the 1pss is something like 1us.
Ok, I know thats not super HF ...
11
votes
4answers
1k views
When laying out circuit board traces, what impedances do i need to consider?
I do low-speed circuit design for microcontrollers and such (usually <20MHz) and now I'm getting started on some more high-speed circuits. What I want to know is:
What considerations need to be ...
3
votes
2answers
591 views
Equivalent time sampling on microcontrolers
I must admit, I don't know too much about analog electronics but I am keen to know if it possible to construct an equivalent time sampler (ETS) using the A/D's on a micro.
I hope this question isn't ...
