Simulating general-parameter LC-ladder filters for monolithic realizations with only transconductance elements and grounded capacitors

A generalized approach based on signal flow graph methods for designing continuous-time active signal processing circuits with only transconductance elements and grounded capacitors is presented. For generating active simulations of LC-ladder filters, the methods result in circuits where all transconductors except possibly one are identical, making the approach extremely convenient for monolithic realization with systematic design and dense layout. Although derived for single-ended devices, it is shown how the methods can be extended to designs based on differential input or even fully balanced transconductors. SPICE simulations demonstrate the validity of the approach and practical design aspects are discussed