| 摘要 |
<p>RCA 82,327 In a radio frequency switch, a pair of diodes is coupled in series with polarities opposed between input and output ports. A shunt diode is coupled between the junction point of the pair of diodes and a point of reference potential. A transistor has its main conduction path coupled between the junction point and the point of reference potential. When the switch is to couple a signal between the input and output ports, a control arrangement applies bias tending to forward bias the pair of diodes, to reverse bias the shunt diode and cut off conduction through the transistor. When the switch is not to couple a signal, the control arrangement applies bias tending to reverse bias the pair of diodes, forward bias the shunt diode, and to bias the transistor into a highly conductive condition, thereby further reducing any difference of potential between the junction point and the point of AC reference potential and cooperating with the bias potential tending to forward bias the shunt diode and reverse bias the pair of diodes. In another embodiment, one diode of the pair of diodes is coupled to the junction point by way of a low-pass filter which does not substantially affect a signal to be coupled but exhibits a high series impedance which increases the attenuation when the switch is not to couple a signal.</p> |
