RF Electronics Chapter 8: Amplifiers: Stability, Noise and Gain Page 300
2022, C. J. Kikkert, James Cook University, ISBN 978-0-6486803-9-0.
Figure 8.33 Stability Factors: a) Amplifier with attenuator. b) Amplifier with optimised Zin.
The technique of inserting an attenuator to make an amplifier unconditionally stable can
also be applied to the BFP540 transistor amplifier of figure 8.19 used in example 3 above.
Using a 50 Ω output impedance, inserting an attenuator and tuning the attenuation and
resistors R1 and R2 results in the circuit of figure 8.34.
Figure 8.34. BFP540 amplifier after tuning to obtain optimum NF and unconditional stability.
Figure 8.35. Gain and NF of amplifier of figure 8.34.
RF Electronics: Design and Simulation
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