A simple cascode circuit with the gate voltage of the cascode transistor being controlled by a feedback ampli #er and thus named `regulated cascode' is presented. In comparison to the standard cascode circuit the minimum output voltage is lower by about 30 to 60 # while the output conductance and the feedback capacitance are lower by about 100 times. An analytical large-signal, small-signal, and noise analysis is carried out. Some applications like current mirrors and voltage ampli#ers are discussed. Finally, experimental results con#rming the theory are presented. I. Introduction C IRCUITS that behave like a MOS transistor but feature a much higher output-impedance and a signi#- cantly lower feedback capacitance are an important prerequisite for the design of high-performance analog circuits. If such a circuit is used in a tail current-source of a di#erential stage, the common-mode and power-supply rejection ratios are improved. If it is used in a voltage ampli#er, a large dc gain-...