| 摘要 |
PURPOSE:To ensure a free variation of the suppressing effect of noise, by adding a bias varying means to the diode. CONSTITUTION:The input signal is divided into low and high band components through the low and high pass filters 12 and 13. The low band component is applied directly to the mixer 14, and the high band component is applied to the same mixer 14 via the noise suppressing circuit 15. The circuit 15 consists of the diode bias control circuit comprising the diodes 18 and 19, resistances 20 and 21 plus the variable resistance 23. The forward bias of the diodes 18 and 19 increases when the value of the resistance 23 is increased. As a result, the cut-off region of the diode is reduced to decrease the noise suppressed region. |
