HBT online it is low noise broadband microwave amplifier

摘要

PURPOSE: To obtain optimum gain bandwidth and low noise performance for a specific system by allowing a low-noise broad-band direct-coupled amplifier to have a 1st and a 2nd feedback resistance having specific resistance. ;CONSTITUTION: A 1st feedback resistance R_f1 determines a shunt feedback quantity for the effective AC load of a 1st amplification stage and a 2nd amplification stage consisting of transistors TRQ2 and TRQ3 and affects gain band performance by giving a current source so as to bias the transistor TRQ1. The 2nd feedback resistance R_f2 gives feedback that can determine gain band response and input matching against system impedance. Further, the resistance R_f2 makes the TRQ1 bias itself to affect the gain, noise index, and its input reflection attenuation quantity performance. Therefore, the resistances R_f1 and R_f2 are so selected as to obtain optimum impedance matching between the system impedance and optimum noise source impedance. Consequently, a user can have a low-noise broad-band amplifier.;COPYRIGHT: (C)1995,JPO