An Evaluation of Bipolar Transistors Suitable for …（双极晶体管适合的评价u2026）.pdfVIP

An Evaluation of Bipolar Transistors Suitable for Active Antenna Applications by Chris Trask / N7ZWY Sonoran Radio Research P.O. Box 25240 Tempe, AZ 85285-5240 Senior Member IEEE Email: christrask@earthlink.net 30 November 2008 Revised 2 December 2008 Revised 5 December 2008 Revised 15 December 2008 Trask, “Bipolar Transistor Evaluation” 1 15 December 2008 Introduction families on a curve tracer or by measuring the performance of the device in a circuit. In the design of active antennas, the intermodulation distortion (IMD) and noise fig- When using a curve tracer, there are a ure (NF) performance of the active devices are number of items that need to be carefully ob- important design considerations together with served in order to ascertain the potential IMD cost and availability. Many designs that have performance of a given device. These include, been published in recent years claim to have but are not limited to, the flatness of the indi- good IMD performance, but make use of de- vidual traces in the linear region, the straight- vices that were obsolete even when the circuitry ness of the individual traces in the linear region, was in the design stage. Other devices that the spacing between the traces, the saturation are readily available have improved perform-