VDDDA - New ‘voltage differencing’ device for analog signal processing

This paper presents a new `voltage differencing´ active building block called voltage differencing differential difference amplifier (VDDDA). The usefulness of the introduced device is demonstrated on novel resistorless voltage-mode first-order all-pass filter and voltage-mode quadrature oscillator design. The pole frequency of the filter can be easily controlled by means of internal transconductance and it provides both high-input and low-output impedances, which is important for cascading. In the oscillator the condition of oscillation and frequency of oscillation can be tuned independently. The theoretical results are verified by SPICE simulations using TSMC 0.18 μm level-7 SCN018 CMOS process parameters with ±0.9 V supply voltages.