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The paper discusses the usefulness and limitations of the modern receiver architectures for software defined radio (SDR) applications. A linear homodyne receiver architecture based on the multi-port technique is introduced and its suitability for SDR applications is discussed in detail. The limitations of the existing six-port based receiver systems are highlighted. The conventional receiver architectures are examined and it is shown that they are not entirely satisfying the requirements of SDR. The multi-port receiver successively avoids the drawbacks of the conventional technical solutions and can be used as a perspective device for modern digital communication. IntroductionContinuous evolution of communication standards in today's information and communication technology sphere demands frequent changes in the communication hardware and the supporting software. Also, a single communication device supporting multiple communication standards might require multiple transceiver units to cater for each standard requirement. The global research community is looking for a generic architecture for communication transceiver units, which can accommodate multiple communication standards or changes in the communication standards and protocols without requiring multiple transceiver units or replacing the existing hardware systems. Software defined radio (SDR) architecture promises to fulfil this requirement by virtue of its flexibility and adaptability to the new communication standard and protocol by changing the accompanying software running on its platform [1]. An SDR transceiver system would include both the transmitter and the receiver subsystems, but the focus of the work carried out in this paper is on the architectures and performances of wireless receivers suitable for SDR applications with special consideration to multi-port based receiver systems. An ideal SDR receiver system will sample the communication signal directly at the receiving antenna [1]. Such a system will require a very broadband (frequency band over which the SDR system is expected to function) antenna and an analogue-to-digital converter (ADC) operating at a sampling frequency of at least twice that of the maximum frequency supported by the receiver system. A comparably faster digital signal processor will be required to process the digitized information. The requirement on the sampling speed of the ADC system and thus the signal processor speed can be relaxed by employing another receiver architecture based on subsampling or bandpass sampling technique [2]. The subsampling receiver architecture provides relaxation in the sampling speed at the cost of

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