An improved CMOS active-R filter

New CMOS building blocks are proposed for inverting and noninverting buffered integrators using only resistors and CMOS transistor arrays. These buildings blocks are then used to design state variable type active-R filters without the use of external capacitors. The new circuits do not suffer the loading problems associated with other active-R realization, and are much less susceptible to distortion and instability. Furthermore, the possibility of voltage tunable filters is demonstrated.