Questions tagged [dds]

A direct digital synthesizer (DDS) creates waveforms from a single frequency reference clock. Typically the reference frequency is fed into a numerically controlled oscillator (NCO) that controls the final frequency and waveform type from where the quantized digital data is converted to analog using a digital to analog converter (DAC).

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DDS example of a reference tone's frequency muliplied by 12000 to generate a master clock

A free project RAM Platter Hybrid aims to generate a master clock from a tone which is 12000 times lower in frequency. The reference tone is 1 kHz at its central frequency. It will have a minimum of 0 ...
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DDS output power

I am designing a circuit that uses a DDS (AD5932) and am having trouble finding its output power. I need to know the power because the output will be fed into a mixer with characteristics that depend ...
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Confusion on what the RF input to a PLL does

I am designing an FMCW radar, for which I need to generate an RF signal ramped in frequency. To accomplish this, I want to use a direct digital synthesizer (DDS) to generate the ramp at baseband then ...
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DDS - find optimal size for LUT, PHACC and sampling freq for application

I had the following question. About the topic of DDS you can find a bunch of information on the net and i think i understood the basics relatively well. You use a lookup-table with stored values of ...
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DDS NBFM transmitter design

As a design exercise I'm trying to come up with a design for NBFM. I'd like to stick with digital domain as much as possible, since that's what I know best. I'm familiar with RF enough to know that I ...
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Multiple Direct Digital Synthesizers (DDS) to Increase Sample Rate

I’m looking to generate a RF signal sampled at around 10 GSPS operating above the 3GHz mark. In order to maximize data throughput, the signal will be modulated at that frequency (rather than mixing in ...
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How to use same low pass filter for square and sine wave

I'm trying to desing simple DDS waveform generator using DDS IC, but I'm a bit lost about designing output filter for it. My requirements are 1 Hz - 25 MHz sine, square and triangle/ramp wave. Using ...
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Amplify 1kHz sine wave from AD9833 DDS using LMH6609 operational amplifier

I'm trying to amplify a 1kHz sine wave signal from the AD9833 DDS chip (0.6Vp-p) to a more usable level (6Vp-p) for a sort of function generator. I plan to work with higher frequencies as well. So I ...
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Reference clock of 400 MHz oscillator or 20 MHz and multiply by 20?

I am trying to design a sinusoidal signal generator using AD9954 which is a Direct Digital Synthesis (DDS) with takes a maximum of 400 MHz crystal oscillator as reference frequency. It also has a ...
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How does stretch processing work for SFCW?

I've been reading about FMCW radar, and I understand that a chirped signal can be de-chirped by mixing it with a copy of itself, which yields a beat frequency which is much easier to process and is ...
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VHDL error during synthesis, declaration and syntax error

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How to correctly configure AD9951 for 10Vp-p, 100Mhz sinusoidal waveform

I am trying to build a function generator for sinusoidal waveform with frequencies ranging from 1 Khz to 100 Mhz with amplitude of about 4 Vp-p to 10 Vp-p. I have been looking at AD9951 DDS that takes ...
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What causes 100Hz spuriour emissions on AD9850 WSPR transmitter?

I've built WSPR transmitter based on AD9850. AD9850 is driven by 125 MHz crystal. TX frequency is 14 Mhz. On the receive side there is upconverter (+125 MHZ crystal) and SDR (both RTL-SDR and AirSpy). ...
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Ripple on tens-millivolts sinus waveform

I’m trying to make a DDS to generate a sinusoidal signal with tens to hundreds of millivolt amplitude and hundreds kHz frequency using an LTC1666 DAC. But I have some confusing results. Device ...
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How to find the RMS value of a sine wave with DC offset and retain the negative sign

I'm trying to build a Quadrature setup where an input signal is mixed with a reference signal that is in-phase and another one out-of-phase by 90deg. The idea is to extract the real and imaginary ...
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8 votes
2 answers
965 views

Accuracy problem of a DDS at very low frequencies

First time in my life I'm using this DDS chip (AD9850) to create sine wave at a desired freq, where I upload the lookup table code and the desired freq. command via a with micro-controller. So my ...
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Is this an artifact of DDS technique?

When I sample a sine wave output of a DDS based bench function generator I have noticed there is always harmonics of the fundamental frequency. For example, below is the function generator's output ...
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A very basic question about tuning-word of a DDS

I have read that a DDS have two inputs one for master clock another for the tuning word. By processing these two inputs the DDS generates the output waveform at a desired frequency. And if I'm not ...
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Frequency response of linear DDS chirp

I am performing a linear frequency sweep from 80 MHz to 120 MHz in 26.84 ms with the AD9910 direct digital synthesiser. I experience that the output amplitude is not constant (see Figure 1). With my ...
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4 votes
5 answers
609 views

Fast (high) frequency hopping with off-the-shelf components

I am looking for the easiest solution to synthesize 1.6 - 2.4 GHz (qudrature) in steps of 4 MHz settle within 10-50ns precise timing control when to switch frequency (e.g., at rising edge of an ...
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direct digital synthesis low pass filter

I am designing a sine wave generator using a dds chip (ad9833). The system parameters are: frequency range of 1-12 MHz spurs and harmonics down to -50 dBc Output power atleast 10 dBm Since the ...
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4 answers
362 views

Can I combine a PLL and a DDS?

I need a controllable frequency for use in a radio transceiver with a range of 3–50MHz (i.e., 80m–6m). The frequency needs to be selectable using a microcontroller. Because chips like the Si5351 tend ...
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711 views

Low-Pass Filter Cutoff Frequency

In the context of direct digital synthesis, I need a low pass filter to reconstruct the analog signal at the output of a DAC. I'm generating only sine wave signals and the maximum carrier frequency is ...
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AD9850 Harmonics at Lower Frequencies

I am wanting to use the AD9850 for a particular application to generate sine wave signals in the 100Hz to 5kHz range. I've purchased a AD9850 module from ebay which just looks like the standard ones ...
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2 answers
182 views

Input clock of a Direct Digital Synthesizer

I need to create a circuit based around one of Analog Digital DDSs (AD9102) to create a sinusoidal signal at 150kHz. For this purpose I think that a clock line at around 10MHz would be sufficient. I ...
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Incorrect signal from signal generator H11887 DDS

I'm a newbie in engineering. I bought this generator on ali and built it. Problem in signal from DDS out: it has incorrect form. I don't have +/- power supply so tested only on +5V. Reasons could be:...
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Formatting DDS Sine Wave output to unsigned decimal

Currently, I am working with the DDS core on Vivado, using Verilog, to generate a sign wave using a phase width of 7 and output width of 12. I understand that DDS formats the output in 2's complement /...
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K50-HC0CSE25.0000MR Clock signal not being driven to correct logic levels

I am using a K50-HC0CSE25.0000MR to generate a 25MHz clock for the DDS IC AD9833. I have hooked up the clock output directly to the MCLK input of AD9833 as shown in the diagram.. The data sheet ...
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9 votes
2 answers
9k views

How to design a cheap sine-wave generator up to 200 MHz?

I want to make a cheap wideband oscillator for an antenna analyzer I'm designing. I want a simple sine wave over a wide frequency range. I don't want to use a DDS IC like the AD9851 because it's ...
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tvalid delay in AXIS

I am trying to feed the cosine wave from the DDS compiler to the multiplier and multiply with another cosine wave. The output of the multiplier is then feed into a CIC compiler as shown below. I have ...
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1 answer
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AD9833 Problems with Arduino and SPI [Can't think of a good title]

Alright I'm about at my wits end, I'm playing around with a AD9833 to synthasize a sin wave. I have combed though all forms of forums regarding the AD9833 to no avail. This is the circuit I'm running. ...
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Using the AD9833 for a 2MHz square wave

Will I be able to accuratley generate a 2MHz square wave using the AD9833 (pdf data sheet) ? I know that as you approach the clock frequency on a DDS you get distorted output signals. I was just ...
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BPSK modulator with DDS on FPGA

I was developing a BPSK modulator with an AD9852. Since AD doesn't seem to offer any way to functionally simulate their DDS ICs, suddenly i see myself in the need to change for a FPGA architecture. I ...
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2 answers
949 views

Unnatural AD9850 Output Attenuation

Yes, another question about this DDS. However, I think mine is sufficiently different from the others I've read. I purchased an AD9850 board on Amazon for $17 from "NooElec" (see here). I've been ...
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How to design a suitable low pass filter for different waveform

I want to realize a DDS signal generator based on FPGA,which is composed of FPGA,DAC and low pass filter,and the FPGA control a DAC to output different kind of signal. Here are the system performance ...
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Digital potentiometer as INA129 gain

I'm working on a waveform generator for which I'm using the DDS AD9833 chip to generate sine signals and triangular signals. I'm trying to amplify these waves since the AD9833 output is 600mVpp and I ...
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2 answers
842 views

Calibrating a TCXO

I'm looking at using the si5351 in a signal generator. It will use a TCXO for improved stability, but I'd still like to calibrate it occasionally. To that end, one of the clock outputs will be set to ...
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2 votes
1 answer
771 views

problem generating Triangle wave using DDS

I'm trying to generate several waves using a Mojo-V3 board, that has a Spartan-6. I use DDS method to generate the waves. The description of the hardware is in VHDL. At the output of the FPGA there is ...
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672 views

DDS with AD9833 and Microcontroller

I'm working on a two channel DDS function generator for a project. I have done some research and I want to use the AD9833 IC controlled with a Microcontroller, an Atmel chip if possible since I have ...
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1 vote
3 answers
4k views

sine wave in FPGA

I am supposed to generate a sine wave in cyclone 2 altera? I get that I have to store the values in LUT or some memory. I think cyclone 2 uses a 4 input LUT. I am not sure how I should go on with the ...
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2 votes
4 answers
3k views

Generating a sine wave over a big frequency range

I want to build a circuit that can generate sine waves at frequencies controlled by a computer or a microcontroller. I would like to go as low as 0.01 Hz (down to 0.05 Hz would probably be acceptable) ...
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4 votes
3 answers
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Replacing Crystal Oscillator with DDS.

In a circuit like this, can the crystal oscillator be replaced with a DDS such as a AD9850? If so can it just be dropped in or would other components have to be changed? Second question, how ...
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1 answer
2k views

Low pass filter design with transimpedance and difference amplifiers

I have a DDS chip with complementary current outputs that I need to filter. I'm using a design like this: I need a different cutoff frequency, however - 2 MHz instead of 50 kHz. Note that I'm not ...
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2 votes
2 answers
464 views

Can an oscilloscope add a frequency component to my signal?

I want to check the spectrum of a DDS signal ("pure" sinewave) for undesired frequency components. The way I am doing it is by storing the waveform from a 2GS/s oscilloscope (Agilent DSO81204) and ...
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2k views

AD9850 can generate others waveform beside sine wave?

As know that AD9850 chip module can generate sine waveform, but does it can generate others waveform? as data sheet of AD9850 didnt mention it
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Can I use ATmega328 TX/RX pins to drive an R2R network and still use the serial port to program the MCU?

Background I wanted to make a simple function generator with an ATmega328 and an R2R resistor network, similar to Jesper Hansen's Mini DDS (Direct Digital Synthesis). To make the function generation ...
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Review and question about AD9838 circuit

I have tried to come up with a schematic of using AD9838. I used the eval. board schematic and modified it to my needs. The eval. board schematic can be found on page 9 here: AD9838 eval. board ...
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1 vote
1 answer
1k views

opamp circuit for amplify up from 1.1V to 5 V

I am doing a DDS function generator with AD 9850 ,because of the charactericts of DAC converter http://www.analog.com/static/imported-files/data_sheets/AD9850.pdf, page 9 figure 5, the output of ...
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2 votes
3 answers
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why the quantised of DAC will affect the amplitude of the output waveform of AD 9850?

By referring to the http://www.analog.com/static/imported-files/data_sheets/AD9850.pdf, for page 9 and figure 5, why the quantized D/A converter affect the amplitude of the output waveform?
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Strange noise on DDS

I have built an FPGA based DDS (fc=200MHz. out: 0-50 or 0-80 MHz) . I have a decent DAC output wave and now trying to build an appropriate filter for it ( Fig-1 ). The filter works rather fine but ...
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