Third order low pass Butterworth characteristic realization using the DBTA

Using the differential buffered and transconductance amplifier (DBTA), together with a unity-gain current mirror cell, a new third order low pass Butterworth filter function realization is presented. The design is practically active-insensitive relative to the port mismatch errors (ε) of the devices and the effect of the parasitic capacitances may be minimized by absorbing their values within the nominal value of the capacitors, all three of which are grounded. The design is verified for 3-db cut-off frequency at f₀ = 5MHz and 10MHz, with both hardware circuit test and by PSPICE simulation.