65 Threads found on edaboard.com: Quartz Pll
I will design a 2nd order pll based on the 74HC4046, using the type 2 phase comparator. The loop has to multiply 16x the reference frequency.
The reference signal is derived from a quartz crystal, so it has very low phase noise, but the RC VCO inside the 74HC4046 has high phase noise.
From what I read before, the loop bandwidth, to reduce the V
Analog Circuit Design :: 18.04.2007 10:39 :: Eugen_E :: Replies: 2 :: Views: 1684
if the main system clock for the hcs12 mcu is 16 mhz and the bust clock is 500 khz i guess that means there is a prescaler of 20 from system to bus clock??is that right?
my question in another way is if i use the pll to derive the system and i doubled the main system clock will that double the bus clock??
IMHO the bus
Microcontrollers :: 10.05.2007 11:23 :: z01z :: Replies: 2 :: Views: 882
Hello there,
I can't find the capacitance value to use for a PIC18F MCU clocked at 40MHz.
I see that from 1MHz up to 25MHz Microchip is proposing 15pF. But no mention for 40MHz.
Anyone can help?
Microcontrollers :: 14.04.2008 17:44 :: jabidof :: Replies: 3 :: Views: 1361
Hi guys,
I'm new here and I am asking your suggestion to solve a radiated emission problem that's afflicting a device I am working on.
I am facing high radiated emissions from a quartz running at 20 MHz frequency (checked that the quartz was the emitter using a sniffer antenna) and the frequency the device "over-emits" at is 160 MHz. I tried in
Professional Hardware and Electronics Design :: 10.11.2009 15:20 :: iules :: Replies: 3 :: Views: 1315
Take a look: High accuracy PIC timing systems
Some very nice ideas.
Thank you, this is very nice reed.
OscTune is only available when using the Internal Osc.
The accuracy of the Int Osc is detailed in the Electrical Specifications of the datasheet +-2% at 25c.
An external crystal would seem the more obv
Microcontrollers :: 25.01.2012 08:51 :: bjuric :: Replies: 11 :: Views: 475
Hi,
I'm running a project on PIC18F46k22 with 20Mhz quartz crystal, In configuration I have selected :
1. HS Oscillator (high power > 16Mhz)
2. Oscillator 4X pll Enable - Oscillator multiplied by 4
Is now the system running at 20 x 4 = 80Mhz or is it at its maximum frequency 64 MHz (as described in datasheet)
I'm bit confused please rep
Microcontrollers :: 04.04.2012 05:45 :: garg29 :: Replies: 4 :: Views: 626
is a 30W transmitter. Generator is based on transistor BC548. The device is also equipped with separators on BF245 and BF199, 1 grade ? also BF199, then 2N2219, KT907a and KT909G. The transmitter should have a low pass filter.
The transmitter has a stereo encoder (with 50us pre-emph
Show DIY :: 05.06.2012 09:42 :: Vermes :: Replies: 0 :: Views: 638
MIl-Std-Hdbk-833 has a base rate for each part number based on history and stress factors based on many design environmental limits, such as operating temp range etc. So the qty pf parts is not as important. Of course actual vendor data is better than generic calcuations, where a failure if analyzed and fixed in a design change then re-verified c
RF, Microwave, Antennas and Optics :: 24.07.2012 03:30 :: SunnySkyguy :: Replies: 10 :: Views: 500
Since all 3 can use a TCXO as a frequency reference, they have exactly equal frequency stability specs.
But the clock is always a TCXO or other reference like rubidium or GPS, so all these are dependent on this stable clock. If clock is not stable, the output of the dds of pll will not be stable as well if I have unde
RF, Microwave, Antennas and Optics :: 15.08.2012 21:12 :: neazoi :: Replies: 3 :: Views: 237
the dividers are quite big according to the schematic. I would suggest to install instead of the quartz oscillator another VCO using a new 4046, which's output connect to the input of your pll's input.
Analog Circuit Design :: 30.08.2012 19:08 :: sztibi82 :: Replies: 1 :: Views: 191
Microcontrollers (well, some anyway) CAN be overclocked to very high levels and still work reliably.
This is due to:
-small die size and high %% od speed reserve.
This is not an Athlon, which heats as a small powerplant. PIC12C5xx, 16Fxx and similar are small beasts, which do not run into serous thermal problem when overclocked.
-Microcon
Professional Hardware and Electronics Design :: 24.04.2002 05:56 :: brankob :: Replies: 11 :: Views: 1696
quartz oscillator 4MHz
divide 8 times by 2 = 15625 Hz
divider: 74xx393
quartz 4MHz is cheaper than 1MHz
Professional Hardware and Electronics Design :: 13.01.2003 03:31 :: thomaz :: Replies: 14 :: Views: 3176
Hi,
I use a 16MHz quartz on my 18f252.
But for futur use I could be interested in speed internal treatments and I would know if I can go over the 40MHz specified by microchip.
thank you.
beuch.
PC Programming and Interfacing :: 15.01.2003 11:59 :: beuch :: Replies: 8 :: Views: 2632
Hi, I've built it, with MC1377,4.43361MHz quartz,added video modulator from old video.R15 at the emmiter of the output is 75 oms.Here is another pattern generator.I've used the pic part from it together with has more options.
Hobby Circuits and Small Projects Problems :: 31.03.2007 16:20 :: tonybg :: Replies: 23 :: Views: 14666
Problems can occur with some quartz crystal oscillator designs subjected to vibration (even very low levels of vibration) - especially in equipment using temperature compensated oscillators. It can also occur do to wire movement resulting in displacement current.
Although probably not a cause in your application cable runs (such as coax) subjec
Professional Hardware and Electronics Design :: 04.02.2003 18:20 :: Beetroots :: Replies: 9 :: Views: 1182
Go to this site, ask for a sample, do your design, check the output level and if is necessary put an amplifier. Beware this is a VCO and the frequency is not very stable if is not part of a pll.
If you are looking for a stable LO, the cheapest way is to start from a quartz frequency (e.x. 101.6
RF, Microwave, Antennas and Optics :: 30.05.2004 23:10 :: vfone :: Replies: 6 :: Views: 1169
This nomenclature (direct vs. indirect) sound "old".
almost every syntetized generators are "indirect".
Direct:
^^^^^
An array of N fixed frequecncy oscillators (i.e. 1,2,4,8,10,20,40,80,100,200,400,800MHz)
An array of N mixers.
With appropriate switch bank you may get an output freq. from 1 to 1665 MHz with 1 MHz step. Lowest phase noise b
RF, Microwave, Antennas and Optics :: 30.05.2004 09:40 :: sergio mariotti :: Replies: 2 :: Views: 1117
I don't know the data sheet you are reading.
But, the VCXO is formally a free running oscillator in the sense that the frequency permitted may vary vs Vcontrol in a small range dominated by the quartz.
For free running oscillator, that it'll be used into a pll circuit, a figure of merit is the phase noise (relatively) far from the carrier.
(I s
RF, Microwave, Antennas and Optics :: 06.08.2004 11:04 :: sergio mariotti :: Replies: 1 :: Views: 627
Hi all,
What is the best choice of oscillator for CMOS microcontroller?
What are the criteria to choose between quartz oscillator (fundamental or overtone)
and internal oscillator? It is considered impractical to design fundamental mode quartz oscillator for frequencies above 25-30 MHz.
What is the upper frequency limit of overtone mode qu
Analog IC Design and Layout :: 12.08.2004 12:10 :: vardan :: Replies: 1 :: Views: 1308
Hi. I work with PIC18F452/8 with quartz 11.0592MHz(x4) and work fine, UART works on 921600 bps link to PC. Also PIC18F6720/8720 wotk on 4x10MHz(its only 25MHz). If your test program access lcd you can with time delay in higher frequencies.
Best Regards.
Microcontrollers :: 01.07.2005 11:17 :: petarpav :: Replies: 35 :: Views: 5971
just another word: It's interestig to plot the phase response by means of a pll. In this technique the quartz is used as a Phase shifter whose phase depend upon frequency. Sending into the quartz a smal sinewave at different frequency by varying the pll programmed freq and analyzing the difference on the locked phase you con (...)
Analog Circuit Design :: 16.12.2004 12:12 :: mrm :: Replies: 11 :: Views: 3201
A crystal is a chunk of quartz with attached wires. You must provide the external circuitry to make it oscillate.
A crystal oscillator is a crystal and oscillator ciruitry in one convenient package. You simply apply power. These cost more than just a crystal.
Many microcontrollers have built-in oscillator circuity, so all you need is a crysta
Analog Circuit Design :: 07.10.2005 06:41 :: echo47 :: Replies: 2 :: Views: 7650
Why do you connect 877-RA1 to 877-RA3, do the pins need the same voltage at the same moment?
In original ICD2 RA3 pin monitors +13V line while RA1 monitoring Target Vcc
My version just supplies ~2.5V to these pins to make ICD2 firmware happy.
It would be better to monitor these voltages separately like real ICD2 does.
DG411
Microcontrollers :: 10.09.2006 00:59 :: Andy_123 :: Replies: 1853 :: Views: 469164
Are you looking for long-term stability? RTC (or any simple quartz crystal for that matter) will drift a milisecond in few days, or sooned, depending on temperature variations and vibration. If you want long-term stability, your options are: quartz trained with 1PPS from GPS (which, like RTC, will give you date and time), or an oven-controlled os
Microcontrollers :: 18.07.2006 04:26 :: kender :: Replies: 4 :: Views: 949
Hi all,
i have a quartz at 100MHz square wave i want to generate 500MHz sinusoidale at output wich component or circuit can do this????
thank s in advance
regards
Analog Circuit Design :: 17.04.2007 09:19 :: voho :: Replies: 3 :: Views: 470
I suspect that the 32 kHz crystal is the cheapest available quartz xtal. To fit a LC oscillator on-chip, you need small L and C, so you have a high oscillator frequency. Integrated loop filter because then you stay on chip and don't have to worry about what a customer implements off chip, and it saves you a little money for external components.
Analog IC Design and Layout :: 06.01.2008 06:50 :: RFDave :: Replies: 9 :: Views: 1244
I use PIC18F4620 at 10MIPS. I have a 10MHz quartz and I activate 4x pll multiplier. I even tested with an oscilloscope to be sure that is 10MIPS.
I don't know nothimg about Atmel, I just intend to begin with Atmel.
Microcontrollers :: 28.01.2008 15:43 :: bld :: Replies: 2 :: Views: 528
I'd evaluate cheapest method against all possible factors involved, not only chipset:
- need MCU for encoding/decoding? If so, why not MCU with transmitter inside? See SilliconLabs, Texas, Adi, Microchip and others
- need one way or two ways. If one way, the cheapest is transmitter + receiver, other ways use transceivers.
- if transceiver, has
RF, Microwave, Antennas and Optics :: 06.05.2011 23:16 :: zuzu :: Replies: 31 :: Views: 4748
Hello,
most simple solution would be 74HC4046A pll with a 10 MHZ oscillator and a 4-Bit binary counter with preset as frequency divider. In my application, I had frequency divider in PLD, I don't remeber the equivalent 74HC counter type. This application must use the PC2 digital phase comparator because of the intended 1:10 pll frequency
Microcontrollers :: 09.02.2008 13:56 :: FvM :: Replies: 6 :: Views: 2821
1. RTFM
2. RTFM
3. yes - you should change to MAX3232 and use 4 charge capacitors 100n and one bypass cap on the voltage supply pin - 100n also. this caps cost almost nothing so don't try to find what will happen if you omit some of them.
4. the best osc is the one you need... RTFM. the oscillation frequency HAS to be divided by two, as this chi
Microcontrollers :: 30.03.2008 11:31 :: Freddie Chopin :: Replies: 3 :: Views: 2125
Hi, I need wary simple telecommand i any frequency. Only thing that it matters is that there is no pll or any delay element like quartz filters. I need it in one direction so it would be one transmitter and one receiver. It is necessary to delay time from moment i enable transmitter to time i detect change on digital out be constant, and strive tow
RF, Microwave, Antennas and Optics :: 08.04.2008 16:25 :: ADRENALIN2003 :: Replies: 0 :: Views: 279
What a attitude " everything is garbage".
I did not say that everything is garbage.
I said that your cheap toy is garbage because other cheap but much better toys have a quartz crystal in their transmitter circuit.
RC transmitters and receivers for model airplanes are fairly inexpensive and are much much
Analog Circuit Design :: 02.11.2008 23:41 :: Audioguru :: Replies: 64 :: Views: 8844
It may be a really stupid question, but did you connect a crystal to your PIC?
Another point is that XT configuration is for oscillators less than 10MHz. If you use a quartz of 10MHz or more, you should use HS configuration.
Microcontrollers :: 30.06.2008 08:33 :: bld :: Replies: 16 :: Views: 11435
thanku mr.audio guru! could you give me a perfect FM transmitter circuit?
The Micromitter is an FM stereo transmitter project in an Australian magazine. It uses a modern IC that uses a quartz crystal in a pll frequency synthesizer circuit for perfect frequency stability and stereo. It has pre-emphasis so it sounds perfect.
Hobby Circuits and Small Projects Problems :: 24.07.2008 16:20 :: Audioguru :: Replies: 20 :: Views: 2078
The dc current of the transistor has little to do with the quartz dissipation. The best is to run the transistor at 15% of Icmax for best phase noise (flicker noise). The trick is to run the crystal at about 50uW , and use the crystal as both resonator and filter .
By the way
Low Phase Noise Oscillators: Theory, Design, and Laboratory
Ins
RF, Microwave, Antennas and Optics :: 05.03.2009 01:43 :: N1UL :: Replies: 110 :: Views: 16452
HI
A crystal oscillator is an electronic circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency. This frequency is commonly used to keep track of time (as in quartz wristwatches), to provide a stable clock signal for digital integrated circuits, and
Electronic Elementary Questions :: 01.06.2009 14:58 :: graciousparul :: Replies: 5 :: Views: 762
Stability is not a function of modulation type !
If you need it to be stable, use a quartz crystal in conjunction with a pll.
Brian.
Analog Circuit Design :: 04.12.2009 20:12 :: betwixt :: Replies: 1 :: Views: 675
With an amplifier it should be fairly easy but we need more information:
1. You mention 5-7MHz, do you mean it has to be tunable in that range, it is at a fixed frequency in that range or it will have a 2MHz bandwidth?
2. How stable does the frequency have to be? Does it need quartz crystal control, pll control or doesn't it matter?
3. Do
Hobby Circuits and Small Projects Problems :: 21.01.2010 10:29 :: betwixt :: Replies: 14 :: Views: 2173
hi to all edaboard member :)
i need to know if there is an cmos or ttl ic that can divide by 384
or i need a circuit that i have from one crystal quartz source clock to frquency 57khz and 1.1875khz
i can obtain these two frequency from xtal 4.332mhz and 12c508b but dont have such xtal so i went to the cmos or ttl
exemple 456/8=57khz
exemple
Electronic Elementary Questions :: 20.05.2010 21:04 :: radium98 :: Replies: 6 :: Views: 988
Hello there:
I have used an old-style microwave counter to stabilize a YIG oscillator at X-band.
The old HP counters had a microwave plug-in unit in which a manually tuned resonator was used, with a discriminator output. An internal precision quartz oscillator at 100 MHz generated harmonics through a comb generator, to which the resonator was
RF, Microwave, Antennas and Optics :: 26.05.2010 23:32 :: jiripolivka :: Replies: 7 :: Views: 2077
I would agree with the drift scenario to a point but you are assuming a good layout and selected components. Even a few pF change in capacitor values from temperature change or variation in supply voltage could make it drift beyond the limits of TV AFC. It also depends on whether the TV is AM or FM as the circuit produces a mix of the two. AM tend
RF, Microwave, Antennas and Optics :: 27.07.2010 10:31 :: betwixt :: Replies: 17 :: Views: 1894
You could derive the tuning voltage, currently taken from the wiper of the potentiometer, from a pll instead and lock it to a quartz crystal. That would give excellent stability but would need a few more components. If you use the pll method, be sure the loop filter response is slow enough that it doesn't 'fight' against your modulation (...)
Hobby Circuits and Small Projects Problems :: 10.10.2010 10:29 :: betwixt :: Replies: 19 :: Views: 1972
Ah , so you are the author of these nice circuits I have found some years ago on the web :) This was among the first websites that let me begin on microwaves, congrats!
The stability is indeed worst when multiplying, but the quartz crystal is ultra stable (let temperature variations alone) and the stability could be much better even on the 10th
RF, Microwave, Antennas and Optics :: 28.02.2011 12:55 :: neazoi :: Replies: 15 :: Views: 469
HI,
I am about to finish my 80 MHz quartz Crystal VCO, but I am not confident on Jitter's results. Please try to answer these questions, as fast as you can, as I have the tape-out in August of the full pll:
1 - For the VCO circuits (autonomous circuits), which jitter measurement type should I use: FM or PM (I am using FM)? I think we should u
Analog Circuit Design :: 12.05.2011 09:55 :: netbug :: Replies: 0 :: Views: 360
An AT cut crystal has a third order Bechmann curve. See attached. A given crystal has a curve based on the mechanical accuracy of the angle of the cut of the crystal blank from the large quartz bar.
Each crystal is unique (but fits a given 3rd order curve) and must be tested by at least a two temperature/frequency points to determine which
RF, Microwave, Antennas and Optics :: 20.05.2011 20:59 :: RCinFLA :: Replies: 9 :: Views: 1045
The reference clock is usually quartz and n the motherboard somewhere. There will be a pll IC nearby which multiplies it to produce the various signals used around the board. One of these will go to the processor which has it's own internal pll to further increase the speed it runs. It wouldn't be feasible to run a fast clock along a PCB (...)
General Computer :: 27.07.2011 10:09 :: betwixt :: Replies: 4 :: Views: 1359
To make a good oscillator, any bipolar or RF FET can be used. I used 2N2222 and many other types.
I would recommend you the ARRL Radio Amateurs' Handbook where you can find good oscillator designs. For both frequencies you can also use quartz crystals tyo stabilize the frequency.
RF, Microwave, Antennas and Optics :: 25.08.2011 17:51 :: jiripolivka :: Replies: 14 :: Views: 489
In your question, the sense is missing.
At ~400 MHz, you can design your local oscillator for instance as a quartz-crystal driven oscillator and a multiplier to the desired frequency.
Or, you can use a VCO with the phase-locking circuit for it. To make a PLO as it is known, you must also make a quartz-crystal driven oscillator and a frequency mul
RF, Microwave, Antennas and Optics :: 27.09.2011 22:15 :: jiripolivka :: Replies: 1 :: Views: 231
This topic is intended for anyone who starts their adventure with PIC microcontrollers and want to build their own circuit. There are countless topics like 'my PIC won' start', 'how to program PICxxxxxxx?', 'my PICxxx resets all the time', 'my flashing led doesn't work' etc.
I want to provide basic information concerning this kind of problems, t
Microcontrollers :: 08.10.2011 14:29 :: poorchava :: Replies: 6 :: Views: 879
It is true, that relatively simple MCU's generate rather low emissions (although not always). Bigger ones as well as FPGA's, CPLD's and so on are often major source of problem. By saying problem I don't mean only compliance with standards about emissions, but also influence of MCU on the rest of the circuit. Especially mixed signal designs are pron
Microcontrollers :: 10.11.2011 08:05 :: poorchava :: Replies: 6 :: Views: 235
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