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Distortion Characteristics of an Even Harmonic Type Direct Conversion Receiver for CDMA Satellite Communications
IEICE TRANSACTIONS on Electronics
Publication Date: 1999/05/25
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,
Full Text: PDF(846KB)>>
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.