DC offset canceller in a direct conversion receiver for QPSK signal reception

Abstract

This paper presents a method to remove the DC offset which degrades the performance of a direct conversion receiver for burst mode QPSK signals. A canceller constructed from analog and digital signal processing circuits is proposed. Computer simulation results show that the canceller has a remarkable function of reducing the degradation in BER (bit error rate) performance by only 0.4 dB. The results show that the proposed offset canceller is suitable for the reception of burst mode QPSK signals such as those employed in NADC (North American Digital Cellular) and PHS (Personal Handy-phone System).