At the time of this writing, S-parameters were available for the BFP620 from 10 MHz to 6 GHz. Initial simulations looked at stability factors K and B ₁. The use of inductive emitter degeneration for the purposes of linearity improvement also had a major impact on the sta bility of the amplifier. In short, a small amount of emitter degeneration improves stability at lower frequencies, but as the amount of emitter inductance is increased, stability at higher frequencies that is, in the range of 5 to 12 GHz is compromised. In simulations, and later confirmed with measurements, output resistive loading (see schematic, R1, 10 ohms) in conjunction with the additional emitter inductance helped to bring K to a value greater than 1, particularly in the range of 800 to 1200 MHz. The RF bypass capacitor C5, 10 pF, has less of an effect at lower frequencies as compared to at 2 GHz. Hence, the LNA output sees this lossy 10 ohm resistor below band, improving stability in that region. Having some stability margin in this range is especially important given that PCS band duplexers typically look very reflective in the 800 to 1200 MHz range.