26 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 04:39 :: Eugen_E :: Replies: 2 :: Views: 1846
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 05:23 :: z01z :: Replies: 2 :: Views: 979
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 11:44 :: jabidof :: Replies: 3 :: Views: 1521
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 :: 03.04.2012 23:45 :: garg29 :: Replies: 4 :: Views: 771
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 03:42 :: Vermes :: Replies: 0 :: Views: 838
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 15:12 :: neazoi :: Replies: 3 :: Views: 353
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 13:08 :: sztibi82 :: Replies: 1 :: Views: 221
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.
PC Programming and Interfacing :: 15.01.2003 05:59 :: beuch :: Replies: 8 :: Views: 2731
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 17:10 :: vfone :: Replies: 6 :: Views: 1270
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.
RF, Microwave, Antennas and Optics :: 06.08.2004 05:04 :: sergio mariotti :: Replies: 1 :: Views: 655
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 06:12 :: mrm :: Replies: 11 :: Views: 3430
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 00:41 :: echo47 :: Replies: 2 :: Views: 9154
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 :: 17.07.2006 22:26 :: kender :: Replies: 4 :: Views: 1043
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
Analog Circuit Design :: 17.04.2007 03:19 :: voho :: Replies: 3 :: Views: 535
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 10:25 :: ADRENALIN2003 :: Replies: 0 :: Views: 299
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 08:58 :: graciousparul :: Replies: 5 :: Views: 800
Stability is not a function of modulation type !
If you need it to be stable, use a quartz crystal in conjunction with a pll.
Analog Circuit Design :: 04.12.2009 14:12 :: betwixt :: Replies: 1 :: Views: 705
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 03:55 :: netbug :: Replies: 0 :: Views: 482
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 04:09 :: betwixt :: Replies: 4 :: Views: 1944
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 16:15 :: jiripolivka :: Replies: 1 :: Views: 253
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 02:05 :: poorchava :: Replies: 6 :: Views: 265
I have designed a double conversion upconverter. Both pll's use a 10 Mhz TXCO as reference.
I should also be able to use an external 10 Mhz reference.
Any suggestions on how to use only one 10 Mhz TXCO for both pll's and to how to switch to an external reference?
Most PLOs utilize 0+/- 6 dBm for 1
RF, Microwave, Antennas and Optics :: 14.03.2012 12:38 :: jiripolivka :: Replies: 4 :: Views: 570
I have a processor of 320 MHz.
What is the clock period of this processor?Or can I clauclate what speed the processor work from this...
Are you talking about the processor and his capabilty to works at the maximum speed of 320Mhz
or about the clock witch drives the processor ( value of a quartz or separate Osci
Microcontrollers :: 11.07.2012 10:16 :: paulfjujo :: Replies: 6 :: Views: 889
this is my first post in here an I hope you can help me. I`m tyring to design a Pierce oscillator @ 450MHz.
My task is, to use a quartz with a basic frequency with, I don`t know... 10-20MHz or a bit more and get to
450MHz with frequency multiplication. I just designed a very simple Colpitts and got it working @ roughly 5MHz.
RF, Microwave, Antennas and Optics :: 13.09.2012 09:41 :: t2theommy :: Replies: 6 :: Views: 469
Hm, I have to put some capacitors as load to chrystal in order to get proper function of oscillator. For that purpose I wanted to ask how is that usually done? How to be sure that oscillator works at specified frequency.
At the moment I am experiencing another problem. I removed quartz for the moment and I am providing external clock signal to the
Hobby Circuits and Small Projects Problems :: 02.08.2013 11:31 :: thranduil :: Replies: 2 :: Views: 209
....Also remember a reset clears the internal clocks (back to 1Mhz if I remember rightly).
Yes, default choice is 1MHZ when using internal oscillator
To avoid change of FOSC at reset , add to the init program :
Microcontrollers :: 05.08.2013 16:56 :: paulfjujo :: Replies: 8 :: Views: 354