Description
Hewlett-Packard’s AT-42085 is a general purpose NPN bipolar transistor that offers excellent high frequency performance. The AT-42085 is housed in a low cost .085" diameter plastic package. The 4 micron emitter-to-emitter pitch enables this transistor to be used in many different functions.
The 20 emitter finger interdigitated geometry yields a medium sized transistor with impedances that are easy to match for low noise and medium power applications. Applications include use in wireless systems as an LNA, gain stage, buffer, oscillator, and mixer. An optimum noise match near 50 Ω up to 1 GHz, makes this device easy to use as a low noise amplifier.
The AT-42085 bipolar transistor is fabricated using Hewlett-Packard’s 10 GHz fT Self-Aligned-Transistor (SAT) process. The die is nitride passivated for surface protection. Excellent device uniformity, performance and reliability are produced by the use of ion implantation, self-alignment techniques, and gold metalization in the fabrication of this device.

Features
• High Output Power:
   20.5 dBm Typical P1 dB at 2.0␣ GHz
• High Gain at 1 dB Compression:
   14.0 dB Typical G1 dBat 2.0␣ GHz
• Low Noise Figure:
   2.0 dB Typical NFOat 2.0␣ GHz
• High Gain-Bandwidth
   Product: 8.0 GHz Typical fT
• Low Cost Plastic Package