Yuanwang Yang

High Performance Waveform Generator Design for Full-Coherent Millimeter-Wave Radar

Millimeter-wave radar has attracted much attention as a replacement of some infrared or laser systems currently in use. In this paper, an approach of developing high performance waveform for full-coherent millimeter-wave radar is proposed. With good frequency configuration and optimal utilization of DDS (direct digital synthesizer), PLL (phase locked loop) and FPGA (field programming gate array), the developed radar waveform generator implemented with low complexity has the good performance of both spectrum purity (phase noise and spur level) and switching speed. The measurement results show that, in S/C band, the local oscillators bandwidth is 480MHz and the minimum frequency step is 15MHz, the spur level is better than -65dBc, the phase noise level is better than -94dBc/Hz@1kHz, the maximum frequency switching time is less than 15mus.

DETECTION AND ESTIMATION OF MULTI- COMPONENT POLYNOMIAL PHASE SIGNALS BY CONSTRUCTING REGULAR CROSS TERMS

A regular cross terms algorithm is derived for the parameter estimation of the multi-component polynomial phase signals in additive white Gaussian noise. The basic idea is flrst to separate its phase parameters into two sets by nonlinear proceduresand then each set has half of the parameters in its auto-terms. Furthermore, using two linear transforms to deal with the two signals respectively, the phase coe-cients of cross terms can be regulated for the identiflcation and elimination of false peaks caused by the cross terms. Simulations are presented to illustrate the performance of the proposed algorithm.

2.4GHz/5GHz wide-band receiver in a wireless communication system based on 4×4 MIMO technology

This paper presents a wide-band receiver at 2.4GHz and 5GHz for 4×4 MIMO wireless communication system. This design is proposed and realized using super heterodyne architecture solution. Dual conversion structure is used in this receiver system. The receiver benefits from RF part, control part and phase shifter part. The carrier of this transceiver is 1.82GHz and 4.42GHz, and the local oscillation providing carrier mainly consists of PLL and DDS. Both 70MHz and 580MHz are intermediate frequency of the receiver, which have 8MHz and 150MHz pass-band channel respectively. The developed receiver is used for field experiments in outdoor wireless communications. The measurement result shows that this receiver developed works well.

A power supply design based on LT3748

This paper describes in detail how to select components of the peripheral circuits of LT3748. In this paper, the LT3748 is introduced to produce an 8Vout at 3A from the nominal input voltage -48V with an operating input voltage range of -38.4V to -72V, where -48V is a common telecommunications equipment voltage. The test results show the output voltage and the current meet the demand of the project and the efficiency of the circuit is about 70%.

The research of homodyne LFMCW radar

Nowadays, the 24GHz band is allowed temporarily for car radars by European Telecommunication Standards Institute (ETSI) until 2013, when the hardware technology (MMICs, antennas, etc.) will be mature enough to enable the development and production of automotive radar modules at the 76-81 GHz band. In this paper, a common structure of homodyne LFMCW (Liner Frequency Modulated Continuous Wave) radar transmitted-received front end and the radar signal processing are discussed. Moreover, taking the 76GHz automatic cruise radar as an example, this paper will discuss the basic measurement principle of relative distance and velocity to target. In the end, some significant conclusions guiding on the project will be achieved.

A novel multiple-tunable millimeter-wave frequency synthesizer

In this paper, a novel multiple-tunable frequency synthesizer structure to achieve both high frequency resolution and fast switching speed without degradation of spurious performance is proposed. According to this structure, a high performance millimeter-wave frequency synthesizer with low spurious, low phase noise, and fast switching speed, is developed. This synthesizer driven by the direct digital synthesizer (DDS) AD9956 can adjust the output of DDS and frequency division ratios of two variable frequency dividers (VFDs) to make the spurious components outside the loop bandwidth of phase-locked loop (PLL). Moreover, the ADF4252 based microwave PLL can further suppress the phase noise. Experimental results from the implemented synthesizer show that remarkable performance improvements have been achieved.

A novel DDS array structure with low phase noise and spurs

Spurious frequencies (spurs) resulting from phase truncation are one of the main spectrum purity issues for direct digital synthesizers (DDS). The standard approach in DDS design consists of truncating the phase word output from the phase accumulator in order to minimize the size of the lookup table. This process generates spurs and degrades the quality of signals at the output of a DDS. The truncation spur can be converted into noise throughout the available bandwidth by adding a pseudo-random sequence to the output of phase accumulator. In principle, since the noise generated by different pseudo-random sequence is quasi-uncorrelated, the combined output noise of multiple channel of dither DDSs will decrease due to their uncorrelated property. In this paper, a novel DDSs array structure on method of combine the output of multiple dithering DDS channels is proposed. First, the paper discusses the methods to suppress the truncation spurs and uncorrelated noise by using phase dithering and parallel DDSs; next, methods for eliminating the truncation spur by combining the output of multiple dithering DDS channels are analyzed to help generate spur-free outputs with low phase noise. Simulation results using MATLAB show that the novel structure can eliminate the truncation spurs without increasing the phase noise.