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46 Threads found on edaboard.com: Dds Pll
I don't know whether you can supply 40 MHz for AD9833s MCLK. Good question. Actually you can't for two reasons. - AD9833 maximum MCLK specification is 25 MHz - PIC18 has no option to output the pll clock More generally speaking, PIC pll configuration has nothing to do with dds frequency. To safe a separate crystal oscill
tcxo... only tcxo is a clock source pll and dds rely on a clock source that determine their stability ...
As far as I know. Lock time only applies if you are using a pll. The dds by design does not have a lock time. The time it needs to change the frequency is just the time to update the phase increment register. Which is added to the phase accumulator on each clock pulse. Frequency changes immediately . Some ddss update this register on the (...)
Well, if you had a choice of using an extremely low noise crystal or saw oscillator at 100 MHz, or a crappy integrated VCO with a pll trying to clean it up inside of the dds, which one would u choose? The phase noise will be AT LEAST 20 Log (Neffective) worse. But there are additional terms...quantization noise, small discrete spurs, digital jitt
AD seems to make some nice dds chips, what do you want to do that they can't do? Those microcontrollers and ARM chips are in small feature low voltage CMOS, so I'd suspect output levels would be pretty low.
HELLO, I want to transmit a IQ wideband chirp of 250 MHz bandwidth at 10GHz frequency.Of the available dds AD9854 is the one with max. 120 MHz bandwidth. since I want a bandwidth of 250 MHz I need to use pll to increase the bandwidth. but how will I use pll ? i need quadrature pll with same reference clock only then it (...)
Hello, Here is a project of Frequency Generator with good performances for Hobbies application, or more ... if you need more accurate , buy Professional Instrument ! Use a PIC18F46K22 because it has a big ROM and RAM memory ! and can run at 40MHZ (Q=10Mhz*pll) -> 1 cycle within 100nS and 27 cycles to build dds output ! so, one
I think you can use the internal divider of an inexpensive pll (f.i. ADF4116) or a dds (f.i. AD9956)
Yes dds has more spurious than pll.They are about -60 or -70dbc and the spurious are much more than pll. It impact on the jitter of LO, so impact the final IF jitter. There is some ways to calculate jitter from spurious, you can estimate with that.
the easies thing would be to use one pll, and split the signal using phase matched cables for each receiver. You can use independent dds synthesizers running off of the same reference (after you take the phase differences out) and use a reset to each dds to restart each at the same phase everytime you change frequency. Similarly, you (...)
multivibrator and other simple oscillators suffer from drift due to aging, temperature deviations and supply voltage variations. pll resolves such problem with locking a vco with a low drift and precision XTAL oscillator(eg. tcxo). also by some modification it is possible to add modulation to the pll but for your application I think dds is (...)
Hi paramis, do you mean a noninteger ratio taking any value in some range? It is possible to have nonintegers multiplier or division frequency ratios using fractional plls or dual-modulus prescalers, but te ratios are always rational (N/M, with integers N and M). With a dds it would be possible a very wide set of possibilities. Regards Z
Hi All, I am reading Alexander Chenakin's Building a Microwave Frequency Synthesizer?Part 4: Improving Performance and saw a dual loop pll topology (Fig. 47) and dds spur reduction (Fig.41 in the article). I couldn't find any specific designs with dds+ dual loop pll topology (schematic+ performance data). Can (...)
Hello, are the spurii close -in to the generated frequency? Usually anything not extremely close-in to the generated freq (and not a harmonic either) can be considered spurii. It can be either conventionally filtered out, or cleaned with pll. So, the effects of SFDR can be combatted on occasions like this. For example, if you look at the AD9954 dat
hi everyone, i am working vhdl implementation of discrete time pll i have coded phase detector basad on analytic signal,loop filter and dds in vhdl now i want to implement the pll on fpga so i want to connect these component how can i connect these in one program please help me its urgent,,,,,,,,,,,,,,, thanks @ regard Ravi kumar (...)
you could also combine a pll with a dds chip, where the dds either sums in a phase shift via a mixer before the divider, or the dds is the pll clock, and you modulate (in small steps) the clock. These only work for low data rates due to pll settling time.
Have you looked HERE?: RF / IF ICs | Mixers / Multipliers Attenuators / VGAs / Filters Switches Integrated Transceivers, Transmitters and Receivers pll Synthesizers / VCOs Detectors Direct Digital Synthesis ( dds) & Modulators Amplifiers Modulators / Demodulators Timing IC
i am working on a frequency hopping transceiver design now i want to synchronize receiver with transmitter hopping frequencies. i am using Dpll for this . i am using a multiplier detector. what filter should i use and how can i make my dds work like VCO as in analog pll. i am working on system generator 9.2.
i am designing a phase lock loop . i need to know how can i convert a frequency input out of LPF in a pll to a corresponding frequency to lock on incoming frequency. do i need to use a dds . i m working in digital domain and input frequency is in binary form. i m using system generator. suggest me some method to do this.
You don't need a license (except the general free Q.uartus web license) for the said basic MegaFunctions. A license (respectively a Q.uartus subscription) is required for e.g. DDR controller, dds, FIR filter. You can clock multiple SERDES instances from a single pll and one pair of pll outputs, if they are using the same clock source (...)
HI saulbit I have some experience on dds and pll hybird frequency synthsizer.if you use the dds output as ADF4107 reference input,the spurs of output spectrum will be amplified as 20*log(N),so the purity of output spectrum won't be well. you can improve the spurs by using mixer-pll,that architecture equalize reducing (...)
Hi, I am trying to build a circuit to multiply frequencies of between 0.4hz and 4Hz by a 12. Which is best to use for such low frequencies, pll, DDL dds or Dpll? And apart from pll (which I kind of know what I need to buy) what are the additional components I'll need to buy in addition? Thanks. maame
Hi friend!, You cannot use Onchip pll(DCM) at such low range frequency....Maybe you can try dds core to generate such freqs....Correct me if I'm wrong
Dear Friends, I have designed a pll using ADF4110 from Analog Devices. The Output of the pll is 180MHz Sine wave. This i need to fed to dds Synthesizer AD9851 4m Analog per the datasheet of AD9851 the reference signal is CMOS/TTL-level pulse i want to convert this 180MHz Sine to TTL(3.5V min) Can some body suggest some IC
Dear Friends, I have designed a pll using ADF4110 from Analog Devices. The Output of the pll is 180MHz Sine wave. This i need to fed to dds Synthesizer AD9851 4m Analog per the datasheet of AD9851 the reference signal is CMOS/TTL-level pulse i want to convert this 180MHz Sine to TTL(3.5V min) Can some body suggest some IC
Use this project:
Use a dds as a reference and modulate the phase with N/R smaller size.
Hi Use a combination of pll synthesizer a dds chip and a mixer to produce a wide frequency range high accuracy signal generator. See Circuit cellar & elektor magazine from 2~3 month ago for project and schematics All the best Bobi
Hello Is it possible to FSK modulate the reference clock input of pll synthesizer IC (for ex ADF4360) with a dds IC(for ex AD9954) to obtain FSK modulated carrier signal? I use a high bandwidth pll loop filter.
I want to have a FSK signal at 1500MHZ,I want to modulate AD9954(crystal 20MHZ ,pll*20) at 100MHZ. The dds have a 1500MHZ spur at -40dBc relative ro main 100MHZ signal, I want to filter out other spur signals and extract 1500MHZ and amplify it to 0dbm. Is this a right way for FSK? What filter should I use and is better to remove spurs?
hello what's about a hybrid pll (using dds)?
Hello Luvu, Your request is practicaly inposible ~2.3% working frequency . It is too wide range for any type of quarz crystal units. You have to change your solutions with alternative like pll or dds are. XTASA
As you may know, AD9858 is a dds produced by Analog Devices. It can be used as a frequency divider, mixer and also a pll. In order to use it as a frequency divider, a clock reference is needed. Consider the case that you are going to generate 100 MHz frequency with the clock of 1 GHz. It is possible that you give it an externally generated clock. B
the pll resultion , as far as i know in integer N pll is the reffence frequency , which si the minimun frequency spacing in fractional N pll this is not the case if u are talking about frequcny accuracy in miili hertz , then u should use dds for highest accuracy and u can deploy the DSS with the pll (...)
Hi to forum I want to make fm modulation to a 1.7 to 1.8 ghz pll . For this purpose i used adf4106 pll with umc vco . I though to drive the reference with dds signal at 40 mhz . My question is how to make fm modulation for fm bradcast signal . I can fm modulate the dds reference so this multiplied produces the needed (...)
if u need generat a new clock frequency , u can do research on dds.
Hi: I want to design a synthesizer at 800MHz-1300MHz with 125KHz steps,I want to use ADF4153 a fractional synthesizer ,is it ok?and how to choose the loop bandwidth?I choose 50Khz,is it ok?what about designing with dds?Thank you!
I want to design a hopping synthesizer dds+pll range: 10MHz-100MHz, channel is 40KHz ,and the Ts<100us,how to design it?can you give me some advice or references? someone told me switching the loop filter with a PIN ?how to do it?Thank you very much
what mean of Spurious? are you want to design dds with pll?
If you don't use a sufficiently good low-pass filter after your dds DAC, then the sinewave will have unwanted frequency spurs that, on an oscilloscope, look like little wiggles or stairsteps or jitter. You don't want that junk going into your pll, or it will wiggle and jitter too.
I think that a traditioonal approach is not possible, because the frequency range is nearly ten times and this requires a change in capacitance of 100 times ( excluding the capacitances of the circuit. ) An easier approach is with the old CD40HC46 of in a new fashion with the dds AD 9850. Mandi
Hi Please elaborate ? what do whant to do : 1) use the pic to control a pll ? - search google for pll + PIC you will find many circuit 2) Use the pic to crate the FM signal (dds alike )- to slow to do the job regards bobi
Digital Frequency Synthesys Demystified, dds and Fractional-N pll, Bar-Giora Goldberg 1999 LLH Technology Publishing. ISBN: 1-8787047-47-7 336 pages Contents Prefaces xi Symbols xv Chapter 1. Introduction to Frequency Synthesis 1 1-1 Introduction and Definitions 1 1-2 Synthesizer Parameters 5 1-2-1 Frequency Range 6 1-2-2 Freque
General topology for hybrid dds+pll Synthesizer: dds is used as the reference clock to the pll synthesizer. You should be awared of the poor broadband spurious performance of the dds clcok. Need to take care of the dds clock leakages, the aliasing products. Advantage: Phase noise of (...)
It depend on the synthesizer. Generally it uses pll methods and so the time to change frequency is in round numbers 2 or 3 times the inverse of the pll loop bandwidth. For dds type generators it is much less than one sine wave cycle time.
So where does a dds fit into the picture? When do you use a dds for synthesis rather than fractional-N plls?