CIRCUIT-DESIGN OF LOW-POWER REFERENCE VOLTAGE SOURCES

The reference voltage source (RVS) is one of the most important functional components in semiconductor integrated voltage stabilizers (VS), and largely determines both the precision and operating characteristics of the voltage stabilizer. If we compare an RVS employing voltage-regulator tubes with RVS's based on forward biased p-n-junctions of integrated bipolar transistors, the advantages of the latter would include a low-reference voltage and current consumption level as well as good long-term stability and low internal noise levels [1, 2]. Methods of constructing RVS's based on forward-biased p-n-junctions and likewise the problems associated with their temperature instability, have been neglected in the literature. In analyzing the temperature instability of such RVS's it is, as a rule, assumed that the emitter-base voltage of an integrated transistor has a linear temperature dependence and, moreover, the temperature coefficients of the resistors are neglected. It is traditionally assumed in deriving a more exact description of the relation U(eb) = f(I(e), T) that the bandgap of silicon has a linear temperature dependence. These assumptions lead to considerable errors (as high as 50-100%) in calculating the temperature instability of RVS's and may be the reason for the choice of incorrect circuits aimed at reducing such instability. This paper analyzes the components of the temperature instability of an RVS based on forward-biased p-n-junctions and uses the result to develop a procedure for designing the circuit of an RVS with improved temperature stability.