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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41 views

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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55 views

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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1answer
67 views

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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62 views

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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70 views

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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2answers
862 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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108 views

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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1answer
54 views

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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125 views

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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5answers
354 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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1answer
207 views

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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4answers
251 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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534 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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1answer
283 views

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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2answers
163 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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1answer
267 views

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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330 views

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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67 views

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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2answers
8k 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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1answer
138 views

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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1answer
3k views

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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2answers
769 views

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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519 views

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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2answers
713 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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1answer
237 views

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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1answer
404 views

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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2answers
684 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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1answer
649 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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1answer
603 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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3answers
3k 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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4answers
2k 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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3answers
1k views

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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1k views

Lowpass 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 - 2MHz instead of 50KHz. Note that I'm not using ...
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2answers
444 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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2answers
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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1answer
4k views

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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1answer
645 views

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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1answer
917 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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3answers
562 views

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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756 views

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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2answers
205 views

High speed counter with step control

I am trying to build my own DDS. I want to make a lookup table (eeprom)that controls steps of a counter and then feed it into a DAC to make a wave form ( something like that Direct Digital ...
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2answers
2k views

Why does my wave signal from AD9850 / AD9851 DDS get cut off?

I have the AD9850 and AD9851 version of this board. I have written the necessary code to interface these with my microcontroller. However, when I sample the sine output signal from the DDS it gets ...
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2answers
1k views

How to identify counterfeit Analog Device products?

Recently I bought two AD9850 DDSs from a friend ( I think he had bought them from his home country).They worked just for minutes! After hours challenging with them, I thought problem is because of my ...
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1answer
1k views

Why AD834+AD811 voltage controlled amplifier does not accept around ground signals?

I have setup a circuit according to page 15 of AD811 Op-Amp datasheet . The design receives 0.5-1.2 vpp sine wave between 1Hz-50MHz from AD9850 DDS and it also has around +0.7 to +1 v offset voltage. ...
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1answer
602 views

AD9850 comparator problem. How to calculate is frequency?

I want to convert a sine wave produced from AD9850 (opens *.pdf) into square wave with its inbuilt comparator. AD9850 has a fast comparator with 3ns rise/fall time and propagation delay= 5.5ns. ...
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2answers
2k views

How to protect a signal from output short circuit?

I have made a signal generator based on DDS and amplified its output to 0-20 V pk-pk. Now I want to prepare the output side. My main concern is short circuit protection to prevent damage to my device. ...
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1answer
1k views

What is optimum maximum frequency of DDS?

According to most DDS datasheets, they can produce up to half the maximum frequency. for example for AD9850, max clock is 125 MHz and it can produce up to 62.5 MHz. But in higher frequencies, the ...
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1answer
936 views

AD9850 just works for a few minutes?

I am trying to drive AD9850 (DDS). First I started with a module , programmed the micro (ATMega128 ) and everything was ok ( It means there may not be a software error). Then I decided to make my own ...
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1answer
3k views

which one is better for smoothing a sine wave: Low pass filters or a serially connected inductor?

Smoothing a sine wave is my main concern in this question. I have a sine wave made by DDS that in higher frequencies shows some steps. Normally in every electronic class it is heard that the best ...