RC-active filters in single-layer tantalum RC-film technology

A new composition of reactively sputtered Ta-oxinitride is used as a basic material for thin-film resistors as well as for thin-film capacitors; this single-layer technique enables an economic fabrication process for integrated RC circuits with lumped or distributed RC components. A bandpass circuit with lumped components for a dialing tone receiver and a voiceband low pass with distributed elements for PCM channel filtering are described; in either case a very small size allowed a complete filter to be packed in regular DIL-packages, and good performance and stability were obtained.