A low-power CMOS continuous-time LMS adaptive filter with robust DC-offset cancellation

Continuous-time LMS (CTLMS) adaptive filter regains researchers´ attention and interest because of its capability of high frequency signal processing. Its advantages of power efficiency and circuitry simplicity make it even more attractive to be applied in communication systems and sensor systems. However, the filtering performance of CTLMS implementation is severely affected by the DC offset caused by the mismatches of the fabricated circuit. To address this problem, this paper proposes a CMOS, low power, continuous-time weight-updating circuit topology with an auto-zeroed multiplier and integrator to cancel the DC offset. Simulation results of a 6 taps transversal adaptive filter utilizing this circuit structure is presented to verify its effectiveness.