Variable gain amplifier building blocks based on MOSFET current dependence on the drain to source voltage

This paper describes two variable gain amplifier building blocks which use MOSFETs operating in triode or saturation regions as basic transconductances. Employing two matched transistors that have all the terminals, except for the drain, connected together, one has the possibility of controlling the drain current using the drain voltage as a control. All the circuits were simulated using the austriamicrosystems 0.35um TDK made available within the Europractice project.