Direct Digital Synthesizer Technique Research Articles

A DDS-based integrated microwave source for fast frequency sweeping in quantum magnetic-resonance systems

Magnetic resonance is a fundamental method to manipulate qubits in spin-based quantum information processing. In such areas, the functionality of fast frequency sweeping is required to determine the resonance of the system. We provide a hardware-synchronized sweeping microwave source with a minimal latency in the sub-μs level based on the direct digital synthesizer technique. The output frequency can be up-converted to match the requirement for particular applications. We demonstrate this module in an optically detected magnetic resonance experiment for a nitrogen-vacancy center, and the spectrum is obtained much faster than conventional schemes with high resolution. Comparing with commercial vector signal generators, our module is highly integrated on a single board with a limited area, especially suitable for engineering of quantum sensors and devices in the future.

Compact phase-lock loop for external cavity diode lasers

We present a compact, low-noise, and inexpensive optical phase-lock loop (OPLL) system to synchronize the frequency and the phase between two external cavity diode lasers. Based on a direct digital synthesizer technique, a programmable radio-frequency generator is implemented as the reference signal source. The OPLL has a narrow beat note linewidth below 1 Hz and a residual mean-square phase error of 0.06 rad2 in a 10 MHz integration bandwidth. The experimental test results prove the competent performance of the system, which is promising as a low-budget choice in atomic physics applications.

DAC를 적용한 DDS Driven Offset PLL모델링 및 설계

In this paper, we presents the modeling and implementation of the DDS(Direct Digital synthesizer) driven offset PLL(Pghase Locked Loop) with DAC(Digital Analog Converter) for coarse tune. The PLL synthesizer was designed for minimizing the size and offset frequency and DDS technique was used for ultra low noise and fast lock up time, also DAC was used for coarse tune. The output phase noise was analyzed by superposition theory with the phase noise transfer function and noise source modeling. the phase noise prediction was evaluated by comparing with the measured data. The designed synthesizer has ultra fast lock time within 6 usec and ultra low phase noise performance of -120 dBc/Hz at 10KHz offset frequency.

Synchronization between Driving and Illumination Signals in a High Frequency Stroboscopic Imaging System

In a stroboscopic imaging system, in order to make images to be correctly captured the synchronization must be strictly satisfied. Direct digital synthesizer (DDS) is a new frequency synthesizing technique used for creating arbitrary waveforms from a single, fixed-frequency reference clock. It has many advantages such as fast frequency conversion, high resolution of frequency and keeping phase continuous while frequency switches. By applying the DDS technique, this paper presents a method to generate the illumination signal of light source and the drive signal of device, and more attention is paid to how to perform the precise synchronization between the two signals. By adjusting the relative delay of the illumination and the drive signals, the phase can be changed. Allowing a sequence of images depicting the motion over the interval studied to be captured, which yields a complete picture of the vibration of a specimen or the surface structure of a MEMS device. Experimental results show that the high frequency of a signal could be up to 120 MHz with frequency resolution 4μHz. The phase resolution of 2-16 can be achieved by the proposed method. The relative phase error between illumination and driven signals could be down to 2-16. It is relatively easy to a synchronization illumination signal of light source and drive signal of MEMS accurately. However, as the two signals' transmission paths are different, their transmission delays are different also. Accordingly, a phase error would be caused and it would change as the signal frequency changes. Moreover, if the drive signal of external objects is used, the phase error, which is introduced via inaccuracy synchronizing the frequency of signal, would be superposed, indeed. These phase errors would affect the quality of imaging and the accuracy of measurement. In this paper, an effective method to adjust the errors is proposed. By means of specially designed hardware circuit, the error of phase and frequency synchronization between illumination signal of light source and drive signal of MEMS can be adjusted automatically. The proposed method improves the accuracy in synchronism and reduces the impact of the error of signal synchronization in the system. It is proved that the minimum relative phase error between illumination signal of light source and drive signal of MEMS can be reduced by more than 10 times using this method.