Synthesis of Leap-Frog Multiple-Loop Feedback OTA-C Filters

Operational transconductance amplifier and capacitor filters based on the leap-frog (LF) structure are studied from the viewpoint of multiple-loop feedback (MLF) and coefficient matching. The LF configuration is obtained from an MLF model, which has the minimum number of components and only grounded capacitors. Explicit and iterative design formulas are derived for the synthesis of arbitrary filter characteristics. All-pole filters are realized using the basic LF structure, and filters with arbitrary transmission zeros are synthesized by adding the input distributor or output summer