Ricerc@Sapienza

The Voltage Conveyor (VCII) is the dual of the second generation Current Conveyor (CCII), and has received only a cursory attention in the literature, probably for lack of interesting applications. The VCII has a current buffer between Y and X terminals, and a voltage buffer between X and Z terminals. In this way, it makes it easier to sum (current) signals at the Y node, whereas CCIIs make it easier to sum (current) signals at the X node. Exploiting this difference between the two dual circuits, a very simple N-port synthesizer can be obtained using only N VCIIs.

A 4th-order Butterworth class-AB current-mode low-pass filter is proposed, based on second-generation Current Conveyors (CCII). Class-AB operation allows high-power efficiency and driving large loads with small quiescent currents. The CCII topology uses the class-AB output buffer with error amplifiers: this topology is known to be sensitive to mismatch errors, which cause offsets in the error amplifiers, affecting the biasing current of the stage. This problem is solved via a control loop, which compensates the effect of mismatches.