| 摘要 |
<p>Switches are cascaded for improved off-state attenuation. The first switch (14) of the cascade comprises an L-type attenuator with series branch including a resistor (16) and a shunt branch including a Zener diode. (22) A bias network (26,28,32) coupled to the attenuator and to the second switch (30) of the cascade connection controls the diode bias for operation at a specific forward conduction when the second switch is open and for operation at a specific reverse bias condition when the second switch is closed for causing the attenuator to provide the plural functions of ( 1 ) enhancing the switch off-state attenuation, (2) providing overvoltage and overcurrent protection for input transients of either polarity and (3) providing a predetermined output DC level when the second switch is on for establishing the DC bias of a subsequent circuit, such as an amplifier, the DC bias so supplied being in a tracking relationship with DC power supplied to the subsequent circuit.</p> |
