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1AP_0059 - Progress In Electromagnetics Research Symposium...

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Progress In Electromagnetics Research Symposium, Hangzhou, China, March 24-28, 2008 59 Frequency Synthesizer Architecture Design for DRM and DAB Receiver Jianzheng Zhou 1 , 2 and Zhigong Wang 1 1 Institute of RF- & OE-ICs, Southeast University, Nanjing, China 2 School of Computer & Information, Hefei University of Technology, Hefei, China Abstract Based on the specifications of DRM/DAB receivers, 4 synthesizer structures were designed for the receiver which supports several radio standards including AM, DRM, FM, and DAB. Comparisons of the characteristics of the four structures were given. Analysis and calcu- lations prove that the synthesizer structure 1 with a single VCO and a single loop filter is the most suitable one to be used in the DRM/DAB receivers with good performance in phase noise, reference spurs and lock time, at expense of little more power consumption. 1. INTRODUCTION A DRM/DAB receiver will need to support several radio standards including AM, DRM, FM, and DAB, and needs to provide the necessary flexibility for seamless receive. A key challenge in the full integration of such a DRM/DAB receiver is the design and implementation of its beating heart, i.e., the reconfigurable frequency synthesizer which acts as the local oscillator (LO) and covers all the frequency bands of the considered standards. This is due to the difficulty in meeting the performance requirements with on-chip components because of the diverse standards it needs to support. It is also due to the simulation of the synthesizer, a task that requires mixed-signal tools that should provide radio frequency, analog, and digital perspectives. We have proved that a double-conversion low-IF structure is the most suitable architecture for the DRM/DAB receiver, and the first intermediate frequency ( f IF1 ) is 36.95 MHz and f IF2 is 2 MHz for DAB, 175 kHz for other bands in this system. The receiver needs two quadrature LO signals, the first one is generated by a synthesizer and the second one is a fixed frequency, which is easy to be generated. So, only the synthesizer which generates the first quadrature LO is discussed in this work. 2. DESIGN SPECIFICATIONS Some of the main design specifications and considerations are given as follows. 2.1. Output Frequency Range and Resolution The output frequency range and resolution of the frequency synthesizer are listed in Table 1. Table 1: The output frequency range and resolution. Band Output frequency range (MHz) Resolution (kHz) LF 37–37.3 3 MF 37.4–38.7 1 HF 39.2–64 5 FM 112.9–145 25 III band 210.9–277 64 L band 1488.9–1529 64 2.2. Phase Noise and Spurious Frequencies Numerical stipulation of phase noise for this design, a typical value of - 80 dBc/Hz @1 kHz is chosen. Generally speaking, all sidebands need to be approximately 70 to 80 dB below the main carrier.
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