Flipped-around multiply-by-two amplifier with unity feedback factor

This letter describes a multiply-by-two amplifier inherently insensitive to capacitor mismatch with an enhanced feedback factor of approximately unity. The proposed flipped-around structure, which operates in a single clock cycle, is based on the series association of two charged capacitors to achieve an accurate gain of two. Due to the series association of the capacitors, a nearly unity feedback factor is achieved, greatly enhancing the energy efficiency of the circuit. Simulations, in a standard 0.13 mu m 1.2 V CMOS technology, also show a fourfold linearity improvement over the conventional structure.