Comparison of 1/f noise in complementary NPN and PNP polysilicon emitter bipolar transistors

摘要

1/f noise was investigated in a complementary polysilicon emitter bipolar process. Noise measurements were carried out for variable base bias resistance (R_S) to analyze how the contribution of each noise source changes as R_S is varied. Two noise measurement setups were used to identify different noise sources in the transistors: noise from the base current (S_(I_B)), collector current (S_(I_C)), and internal resistances (S_(V_r)). The coherence for transistors measured in both measurement setups were close to unity, implying a single dominant noise source. S_(I_B) had the dominant contribution at lower bias currents. In this case, R_S was relatively larger than the input resistance of the transistor. Higher current measurements with a smaller R_S showed a dominant contribution from S_V . S_(I_B) was modeled as a combination of the minority carrier diffusion fluctuations in the monosilicon and polysilicon emitter, and tunneling fluctuations through the interfacial oxide. A combination of the number and diffusion fluctuations of the minority carriers in the base was used to model S_(I_C) . It was concluded that S_(V_r) mainly originates from the fluctuations in the internal emitter resistance, which was ascribed to the tunneling fluctuations of the majority carriers through the interfacial oxide.