A low-noise direct conversion PSK receiver for TDMA land mobile communications

This paper presents a new scheme of direct conversion phase shift keying (PSK) receivers applicable to time division multiple access (TDMA) land mobile communication systems. In the scheme, a matched filter in each I and Q channel is divided into two parts in front and at the back of a baseband amplifier to reduce baseband noise power and improve sensitivity. A rational design method to divide the filter is proposed; the filter cell that has narrowest equivalent noise bandwidth in the filter is chosen as the back part, while the remainder constitutes the front part. Moreover, memories are employed to eliminate DC offset in baseband signals. Experimental results show that, when applied to Personal Handy Phone System (PHS), a receiver employing the scheme achieves sensitivity comparable to that of a super-heterodyne receiver in continuous and burst reception