Temperature variations effects in BJT amplifier circuits at Radio Frequencies

Kamaljeet Singh* & A V Nirmal
Page No. 1-7

Bias stability is an important parameter in amplifier design as small shift renders oscillations in the
circuits beside shift in the desired operating value. Transistor DC points are prone to changes due
to temperature variations as temperature effects the intrinsic parameters of the transistor rather
than the extrinsic parameters. The bias point shifts due to hot and cold temperature variations
which is due to the Quiescent-point shifting to the upper and lower side of the load line causing
clipping and distortion of the waveform. Variation in the temperature and operating conditions in
the amplifier for on-board systems results in the degradation of the gain and noise figure. This
article details the various parameters of transistor affected by the temperature variation and further
shows the practical analogy for the same.
Keywords : Transistor, temperature, bias point, stability.