Comments and Remarks over Classic Linear Loop-Gain Method for Oscillator Design and Analysis. New Proposed Method Based on NDF/RRT

Abstract

Present paper describes a new method for designing oscillators based on the Normalized Determinant Function (NDF) and Return Relations (RRT ). First a review of the loop-gain method will be performed, showing pros, cons and including some examples for exploring wrong so- lutions provided by this method. Wrong solutions, because some conditions have to be previously fulfilled in order to obtain right ones, which will be described and finally, demonstrate that NDF analysis is necessary, including Return Relations (RRT ) usefulness, which in fact are related with the True Loop-Gain. Finally concluding this paper, steps for oscillator design and analysis, using the proposed NDF/RRT method will be presented, compared to wrong previous solutions pointing out new accuracy achieved on oscillation frequency and QL prediction. Also, more new examples, of plane reference oscillators (Z/Y/rho), will be added for which loop gain method application is clearly difficult or even impossible, solving them with the new proposed NDF/RRT method.

Keywords

• Oscillator
• Normalized Determinant Function
• NDF
• Stability
• Loop-Gai