Design of a SiGe BiCMOS canceller for low frequency noise reduction in direct conversion receivers

Direct-conversion receivers are increasingly employed in many applications, such as wireless communications and radars. Indeed, they represent an effective alternative to heterodyne receivers, as they allow a higher level of integration. However, performance limitations are imposed by the leakage of the local oscillator (LO) toward the RF port of the mixer (Figure 1(a)). This causes the LO self-mixing phenomenon, which is responsible of a significant DC offset at the output of the receiver (Figure 1(b)). In turn, this DC offset gives rise to a high level of low frequency noise affecting the signal recovery at baseband (R. S. Michaelsen et al., IEEE Microwave and Wireless Components Letters, Vol. 23 No. 2, 2013, pp. 66–68).