| 摘要 |
PURPOSE: To extend a dynamic range while eliminating an error due to dispersion or the like in an Is in the logarithmic transformation circuit where logarithmic transformation is conducted by utilizing a logarithmic relation between a base-emitter forward current (base current) of a transistor(TR) and a base- emitter forward voltage (VBE). CONSTITUTION: The circuit is made up of a TR Q1 receiving an input current Iin as an emitter current, a TR Q2 whose base connects to a base of the TR Q1, a feedback TR Q3 whose base connects to an emitter of the TR Q1, whose emitter receives a reference potential to control a base current to be fed to the TRs Q1, Q2 with respect to their input current to be constant, and a TR Q4 whose base connects to the emitter of the TR Q2 to shift the emitter potential of the TR Q2 in a direction of cancelling the VBE of the TR Q2. |
