Intermediate Bandwidth Quartz Crystal Filters - A Simple Approach to Predistortion,
Abstract
Intermediate band crystal filters can realize fractional bandwidths of more than 1%, but design and construction difficulties have severely limited their general use, despite the considerable number of practical applications. These filters rely on coils to broadband the response, and the effect of coil losses increases in proportion of the filter bandwidth. This paper describes the development of a 15 MHz crystal filter with a 1% fractional bandwidth. An eight order elliptic characteristic was chosen (C0825b 48), using a two crystal lattice configuration. The bandwidth of the filter was severely narrowbanded by coil losses, and it was found to be necessary to use optimization techniques to meet the required specification. As a result a special computer programme was developed which would provide a near optimal design allowing for an arbitrary distribution of coil losses in the chosen circuit configuration, but which only required minimal computational effort and was almost foolproof in use. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1982
- Accession Number
- ADP001548
Entities
People
- A. J. Byrne
- A. J. Dyer
- E. Read
- J. K. Stevenson
- R. C. Peach
Organizations
- General Electric