| Summary: | 碩士 === 逢甲大學 === 自動控制工程所 === 91 === Orthogonal Frequency Division Multiplexing (OFDM) is the most possible candidate for 4G mobile transmission technology, which has been applied for Digital Audio Broadcast (DAB), Digital Video Broadcast (DVB) and IEEE802.11a standard such the wireless LAN (WLAN) in 5GHz band in the recently years. Due to that OFDM is a multi-carrier transmission technique, which divides each high-speed transmission data into low speed protocol data form, and transmit it by individual carrier. Thus, the OFDM has the advantage such as raising bandwidth usability, reducing noise, increasing security and solving the multi-path fading.
In this thesis, the circuits of 16-level Quadrature Amplitude Modulation (QAM) applied in Orthogonal Frequency Division Multiplexing (OFDM) are design. In this modulator, choosing Raised-Cosine Nyquist filter represents the shaping filters, which combined the Transpose Direct Form (TDF) and Time-Shared Form to obtain a new high performance structure. Besides, the phase different of carrier is produced by Direct Digital Frequency Synthesizer (DDFS) to increase operation speed and correction. The whole circuit is accomplished and verified in Complex Programmable Logic Device (CPLD). Chip’s data process rate reach 463ns in CPLD, which can meet the system specification of 3.2us. The total area is 2958 logic cells.
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