ROMJIST Volume 23, No. 2, 2020, pp. 204-220
Gabriel BONTEANU, Arcadie CRACAN, Ioan Alexandru NICA, Stefan Viorel SAVINESCU A comparison between the Gm based implementations of voltage mode and current mode capacitance multipliers
ABSTRACT: A comparison between two Gm based implementations of capacitance multipliers, one following a voltage mode perspective and another one following a current mode perspective is performed. The transconductor based circuit solution for voltage mode capacitance multiplication employs the Miller effect around a voltage amplifier implemented as a transconductance amplifier paired with another transconductor acting as a load. The current mode multiplier used as reference in the comparison uses the same components and is built around a typical current mirror by substituting the MOS transistors with transconductance amplifiers. For both structures the ratio of the two transconductances defines the multiplication factor. Due to the transconductance tunability, the multiplication factor is adjustable in a wide range. The results show an important advantage of the voltage mode multiplier with regards to the low frequency behavior in comparison to a current mode Gm-based implementation, recommending the voltage mode circuit for frequency compensation applications. A first order low-pass filter is implemented as an application of the two described architectures using discrete Gm integrated circuits. KEYWORDS: MOS capacitor; capacitance multiplier; adjustable capacitor; transconductance amplifierRead full text (pdf)