Low-Power High Parallel Load Resistance Current-Mode Grounded and Floating Capacitor Multiplier

A current-mode capacitor multiplier using a high performance voltage follower is presented. The architecture has the ability to balance between very low equivalent series resistance of a few tens of ohms due to the voltage follower and very low power consumption achieved by means of reducing the biasing current in the output devices, forcing them to operate in subthreshold during static conditions, which, in consequence, results in an increased parallel load resistance. Analysis shows that one corner frequency is shifted by the gain factor of a transistor as an amplifying device, thus increasing the frequency range of operation. This is achieved with very few additional devices and without compromising accuracy. The architecture of a floating equivalent capacitor is also presented. Experimental results of a prototype chip fabricated in 0.5- μm CMOS technology show the operation of the proposed circuits used in an low-pass, high-pass, and notch filters.