AN FM Front End with a High Gain Unneutralized JFET

Based on the most commonly used circuit for the FM RF amplifier, criteria for optimum device characteristics are developed. A survey of available junction FET´s indicates that they might be graded into three generations, examples of which are then judged in light of the criteria above and the performance required in this application. Practical use of second generation devices is shown to require either a neutralized, or a cascode configuration. An unneutralized third generation JFET circuit is compared to neutralized and cascode circuits with second generation devices to show the significance of the difference between generations.