Front-End Filters for Software Radio Receivers Employing Bandpass Sampling

Bandpass sampling holds much promise for the realisation of software radio receivers, particularly for mobile devices. Sampling at reduced rates eases many of the ADC requirements, and decreases power consumption, thus increasing battery lifetime, and overall receiver size. The need for very high performance programmable devices is also reduced. This paper demonstrates the importance of the bandpass filter at the front-end of bandpass sampling receivers, and investigates the bandpass filter requirements for QPSK, and π/4-DQPSK modulation schemes. Also considered is a practical software radio receiver where channel selection occurs at baseband.