| 摘要 |
PURPOSE:To attain the temperature compensation of a diode by providing a voltage dividing type compressiong circuit comprising a resistor and a series circuit consisting of diodes of anti-parallel connection and a resistor to a signal compression circuit to make the input sensitivity curve variable easily. CONSTITUTION:When a sinusoidal wave Vi is inputted to a terminal A, a non-inverting input Vs of an amplifier 7 becomes Vs=kT/q.ln(ID/Is)+R4ID, where ID is a diode current and Is is a reverse current of diode. The 1st term of equation expressing Vs is dominant when ID(Vi) is small and the 2nd term is dominant when the ID(Vi) is large. The sensitivity curve of the compressing circuit changing from this logarithmic compression into linear range is changed by changing the value of resistors 1, 4. Further, the current is increased by DELTAID when the forward voltage of the diode is decreased because of temperature change, the Vs is about to increase by DELTAIDR4 by changing the resistor R4, resulting in that the circuit acts like compensating the change in the Vs due to temperature. |
