A GaAs MESFET three-terminal varactor diode fabricated on a semi-insulating substrate can be used for the MMIC active voltage-controlled filter because it is compatible with the standard GaAs MMIC process. The high ca...A GaAs MESFET three-terminal varactor diode fabricated on a semi-insulating substrate can be used for the MMIC active voltage-controlled filter because it is compatible with the standard GaAs MMIC process. The high capacitance ratio needed for wideband tuning filter requires the three-terminal varactor diode (TTVD) to be biased up pinch-off voltage or positive bias. Therefore a variable-capacitance model is applied to analyzing C-V characteristics of this TTVD. The earlier capacitance model for GaAs MESFET did not consider the free carrier move in active region which can cause varying the C-V characteristic, but only depletion layer model approximation. The new model described here takes into account the free carrier move for contributing to gate capacitance. The model analytical results agree well with experiment.展开更多
文摘A GaAs MESFET three-terminal varactor diode fabricated on a semi-insulating substrate can be used for the MMIC active voltage-controlled filter because it is compatible with the standard GaAs MMIC process. The high capacitance ratio needed for wideband tuning filter requires the three-terminal varactor diode (TTVD) to be biased up pinch-off voltage or positive bias. Therefore a variable-capacitance model is applied to analyzing C-V characteristics of this TTVD. The earlier capacitance model for GaAs MESFET did not consider the free carrier move in active region which can cause varying the C-V characteristic, but only depletion layer model approximation. The new model described here takes into account the free carrier move for contributing to gate capacitance. The model analytical results agree well with experiment.
