Distortion Characteristics of an Even Harmonic Type Direct Conversion Receiver for CDMA Satellite Communications

Hiroshi IKEMATSU  Ken'ichi TAJIMA  Kenji KAWAKAMI  Kenji ITOH  Yoji ISOTA  Osami ISHIDA  

IEICE TRANSACTIONS on Electronics   Vol.E82-C   No.5   pp.699-707
Publication Date: 1999/05/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Low Distortion Technology for Microwave Devices and Circuits)
direct conversion,  mixer,  diode,  third-order intermodulation,  noise power ratio,  

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This paper describes the distortion characteristics of an even harmonic type direct converter (EH-DC) used in earth stations for CDMA satellite communications. Direct conversion technique is known as a method to simplify circuit topologies of microwave transceivers. In satellite communications, multi carriers which have high and nearly equal level are provided to a quadrature mixer of the EH-DC. Hence, the third-order intermodulation degrades receiving characteristics. In this paper, we show the relationship between the distortion characteristics and noise figure of the EH-DC for CDMA satellite communication systems. Furthermore, we show NPR of even harmonic quadrature mixers caused by the third-order intermodulation. Experimental results in X-band indicate that the proposed EH-DC has almost the same BER characteristics compared with a heterodyne type transceiver.