| 摘要 |
An attenuator element has a reference path and a relative attenuation path. The reference path is formed by a T-network of two FETs operated in the passive mode and a shunt path and the attenuation path is formed with a similar structure, with the FETs in the shunt path having a different channel width. Instead of a T-network, a Pi-network of transistors can be used. The respective gates of the FETs along the reference path are connected to a first control input corresponding to either zero volts or the pinch-off voltage and the respective gates of the transistors on the attenuation path are connected to a complementary control input having a voltage corresponding to the other of zero volts and the pinch-off voltage. Another type of attenuator element is formed with a reference path having a transmission line and an attenuation path formed by a resistive T-network, with the attenuation and reference paths being alternately selectable by two single pole, double throw switches. The switches can also be formed by FETs operated in the passive mode, and be controlled by a control signals corresponding to either zero volts or the pinch-off voltage. Using one type or mixing both types of attenuator elements, an attenuator device is formed. The attenuator may be used in any attenuator application, and is especially applicable to on-board transponder applications in a communications satellite, and phased array antenna and radar applications.
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