| 摘要 |
PURPOSE:To reduce number of integrated circuit elements by shifting the level of a base of the 1st NPN detection circuit transistor (TR) by a base-emitter voltage of the 1st PNP TR while using the 1st level shift PNP TR so as to eliminate the need for an input capacitor and a 1/2 Vcc reference power supply circuit. CONSTITUTION:When an AC signal is inputted to a terminal 10, an AC input signal is deflected around a GND level and the level of the AC input signal is shifted by an emitter-base voltage of a Q7, VBE by using a current source I2 and a level shift circuit comprising the TR Q7. The AC input signal subjected to level shift is detected by an NPN TR Q8 for a half wave. The signal subjected to half wave detection is amplified as a current by using PNP TRs Q9, Q10, an NPN TR Q11 and resistors R6-R8, smoothed by a smoothing circuit capacitor 14 and a smoothing circuit resistor 13 and a DC potential is outputted at a terminal 12.
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