Performance analysis of a monolithic integrated transversal filter using mixed-mode scattering parameters

A broadband transversal filter based on a new cell design that enables positive and negative tap gain weight control is proposed and its behaviour is analysed in the frequency domain. The non-ideal behaviour of distributed circuits and associated effects on the functional characteristics of an integrated transversal filter design are examined through consideration of the principles of generic differential circuits. It is shown that the transversal filter can be modelled as a coupled-pair drain line structure with the ability to propagate both common and differential-mode signals. Coupled wave interactions on artificial transmission lines are characterised using a set of derived mixed-mode scattering parameters and voltage and current phasors at input/output ports of a monolithic filter design. Analytical and simulation results confirm the suitability of the approach for broadband filter implementations, in applications requiring predefined time-domain responses as in high-speed correlators and encoders as used in optical code division multiple access (CDMA) systems.