Theory and Performance of N-Path Filters
Abstract
The paper has five major sections. In the first, the periodic time varying network with N-identical paths operating between modulators is examined theoretically by the use of Laplace transforms. The transfer function is derived generally and then expanded for sinusoidal and rectangular modulation. In both cases the low-pass to band-pass characteristic is retained assuming low- pass elements in each path. The next section investigates theoretically, the effects of using other than low-pass elements in the N-paths. The results are such that, if a high-pass, first order all-pass, or a simple band-pass are used in the N-paths the resultant transfer function became a variable attenuator, a notch filter or a pair of adjacent band-pass filters respectively. The third major area is that of switching variations. A more practically oriented configuration is introduced, its transfer function variations are determined and then parallel switching is discussed. In the last sections, the real world tolerances and other variations of the components are accounted for in the transfer function of the N-path filter and their effects are noted in five disturbance categories, most serious of which are the variations in the modulating waveforms. Then finally there is a detailed implementation of an N-path filter for use in an IF of an AM/FM receiver which was introduced earlier in the literature. This application makes use of electronic bandwidth and frequency variations.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1971
- Accession Number
- AD0727140
Entities
People
- Allston L. Jones
Organizations
- Stanford University