OFDM用低位相雑音局部発振器の設計と搬送波のS/N特性検討

抄録

Orthogonal frequency division multiplex (OFDM) is a suitable digital modulation method for terrestrial digital broadcasting systems. It is important to reduce a phase noise in an OFDM receiver, because the phase noise disturbes orthogonality among the OFDM sub-carriers. This report describes design of a wideband tunable local oscillator with low phase noise characteristics for OFDM receivers. We have newly developed a balanced type oscillator with an L-C pararell resonance circuit between the transistor emitter ports, which has wide band frequency range of 1.15〜2.2GHz and low phase noise performances of-66dBc/Hz (1KHz offset) or less. Also, we calculated the SNR at the output of the tuner of OFDM sub-carriers by using above balanced type oscillator, and the results show that the SNRs of 33dB or more are achievable even for the 1KHz sub-carrier spacing system.