PURPOSE: To detect even a small input signal and to obtain a demodulated signal with small distortion by using a silicon diode as a diode for detection, and applying the DC bias of the forward voltage drop across the silicon diode to a silicon diode of the same type which is provided separately.
CONSTITUTION: A DC current is flowed to the silicon diode 10 of the same type with the silicon diode 7 as the diode for detection from a DC voltage source 8 through a resistance 9 to obtain the forward voltage drop Vf across the silicon diode 10, and this voltage Vf is supplied to the diode 7 through a resistance 11 as a forward DC bias. Therefore, a forward DC bias Vf' is supplied to the silicon diode 7, so an operation point is set almost to an on voltage VON as shown in a figure, and then detection having no distortion is performed by utilizing the good voltage-current linearity of the silicon diode and even a small input signal is detected.
MABUCHI HIROSHI
NAITOU SEIGO
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