36
votes
Accepted
Why do microwave ovens use magnetrons?
Magnetrons are cheap, reliable, pretty efficient (65% or so- and they tolerate high temperatures so heat sinking is easy) and made with mature technology. They are also reasonably tolerant of VSWR ...
- 385k
19
votes
Accepted
How do digital function generators generate precise frequencies?
That sort of generator uses DDS, or Direct Digital Synthesis
It keeps track of the phase of the required output in a register, and outputs the cosine of the phase.
To use nice round numbers, let's say ...
- 162k
12
votes
Why do microwave ovens use magnetrons?
The domestic microwave oven needs high power to cook the meal and high frequency to excite the water molecules. What is not needed is high stability because the water energy absorption spectrum is ...
- 14.3k
6
votes
How do digital function generators generate precise frequencies?
You can teardown your cheap function generator, I am certain you will find a DDS chip or a FPGA doing the same. However it is possible to increment/decrement frequency in range of milihertz but the ...
- 23.7k
6
votes
What is the difference between a PLL and a frequency-synthesizer？
According to Wikipedia a frequency synthesizer
is an electronic circuit that generates a range of frequencies from a single reference frequency.
A block schematic could look like:
And I see a ...
- 80.5k
4
votes
Accepted
What is the difference between a PLL and a frequency-synthesizer？
A PLL is a specific type of building block, that will control a variable oscillator (usually a VCO, though it doesn't have to be voltage-controlled - YIG-based PLLs use current instead) such that it's ...
- 12.4k
3
votes
How do digital function generators generate precise frequencies?
Neil and Marko have already responded in great detail.
From my superficial point of view: the generator contains a DAC (or several DAC channels) and performs PCM wave playback. The design tradeoffs ...
- 2,613
3
votes
Is an MPU capable of equal quality digital synthesis as a dedicated DSP chip?
I'm no expert on the topic. I'm a hobbyist, at most, today. I watch the news, buy and test out development boards from time to time, and broadly speaking enjoy the subject area of DSP processing. I've ...
- 77.5k
3
votes
What is the difference between a PLL and a frequency-synthesizer？
"Frequency synthesizer" is just a more general term than "PLL". Every PLL is a frequency synthesizer but not vice versa.
A PLL is one common type of several possible types of frequency synthesizers. ...
- 16.2k
2
votes
How to get a high precision sine wave not available from standard crystal?
Filtering the output of the digital programmable oscillator you have to obtain a sine wave would be simple and accurate reliable way. I have not used your device but have used the DSC8001 programmable ...
- 22.2k
2
votes
Accepted
Fast (high) frequency hopping with off-the-shelf components
One option is using a DDS that can reach 1.2 GHz, with a frequency doubler.
Doublers are essentially just some nonlinear circuit to produce harmonics with some filtering to pick out the preferred 2nd ...
- 128k
2
votes
Accepted
Unnatural AD9850 Output Attenuation
I use the AD9850 board from NooElec, purchased on Amazon. However, the unit I bought was described for up to 40 MHz. I used it to build Antenna Analyzer
I measure voltage at the junction of C1 and ...
- 5,240
2
votes
Is an MPU capable of equal quality digital synthesis as a dedicated DSP chip?
The one algorithm that makes a difference is the fast Fourier transform (FFT) that is needed for filtering and overtone shaping. DSPs would have an optimized hardware implementation, however with a ...
- 339
2
votes
Is an MPU capable of equal quality digital synthesis as a dedicated DSP chip?
It depends what you mean by 'quality'.
It's generally the case that a piece of hardware dedicated to one particular job will be an order of magnitude or two faster and more power efficient than ...
- 162k
1
vote
Fractional N Synthesis and Frequency Meters
On a 19kHz frequency, if your gate time is one second, then most of the time it will count 19000 cycles... and sometimes it will count 18999 or 19001, depending if the 19kHz oscillator is slightly off ...
- 72.2k
1
vote
Disadvantages of DLL clock generators compared to PLL
There are a number of disadvantages to DLLs. The four I can think of right now:
The delay though each element is often highly temperature dependent, which means the number of delay elements changes ...
- 22.1k
1
vote
Why do microwave ovens use magnetrons?
For a linear circuit, In the best-case, you can transfer 50% of your input power to the wave and the other 50% energy heat up your circuits.
"https://www.microwaves101.com/encyclopedias/maximum-power-...
- 411
1
vote
Fast (high) frequency hopping with off-the-shelf components
You can use a AWG + DDS + Marki IQ-1545 IQ Mixer if you need to have baseband modulation. (Else a DDS can have good results on CW frequency hopping). There are always IQ mismatch in component. You ...
- 298
1
vote
Accepted
Are there still programmable clock synthesizers with single ended TTL output leves (in 2019)?
You can use a Silicon Labs synthesizer chip such as Si5351 (there may be more appropriate part selections). It's not 5V so you'll also need a voltage translator chip and something to program it over ...
- 385k
1
vote
Measuring Frequency Synthesizer specifications
The TB-567 appears to be a generic test board you can use to evaluate several models (maybe families) of Minicircuits devices.
You get a TB-567 and mount your synthesizer on it.
You use the TB-...
- 69.2k
1
vote
Generating a 10MHz modulated signal
Solutions that come to mind:
Microcontroller + DAC: The use of DSP / DDS (direct digital synthesis) techniques on a fast microcontroller (preferably with an integrated FPU) to generate a frequency ...
- 185
1
vote
Fast (high) frequency hopping with off-the-shelf components
Referring to your list of requirements, synthesizing up to 2.4 GHz (quadrature) and settling within 10-50 ns are probably the main parameters limiting your choices of synthesis method. It rules out ...
- 269
1
vote
How to get a high precision sine wave not available from standard crystal?
Firstly, why the fascination with sine waves?
You have a very narrow band transmit coil with lots of Q if you want reasonable efficiency and you are not doing any tricky modulation, so I would be ...
- 17.4k
1
vote
How to get a high precision sine wave not available from standard crystal?
To expand on Tony's and Andy's answers: Let's do a prime factorization of your frequency:
$$ 27095000\,\text{Hz} = 5419 \cdot 2^3 \cdot 5^4 \,\text{Hz}$$
Square waves have every odd multiple of ...
- 91k
1
vote
Accepted
Frequency Synthesis from 1MHz to 800MHz
Texas Instruments has a component that can do the majority of your desired RF output range: LMX2571. At around $12, quantity 1, on Digikey, this will successfully implement 10MHz to >1GHz signal ...
- 2,888
1
vote
Help to translate jitter design constraint in a frequency synthesizer design with 4046 and 4017 ICs
I will define jitter specifically as the cycle to cycle jitter, so the time variation from one cycle to the next compared to a perfect cycle period. This is a common jitter definition and will allow ...
- 488
Only top scored, non community-wiki answers of a minimum length are eligible