Automatic control of the operating point of radio-frequency field-effect transistors in keyed pulse mode

摘要

A circuit arrangement (10) for the controlled stabilisation of the operating point of a radio-frequency power field-effect transistor (11), the gate electrode (12) of which coupled to the radio-frequency input (16) and the drain electrode (13) of which coupled to the radio-frequency output (17) are in each case DC-decoupled from the input and the output via a capacitor (C1 and, respectively, C4), has a DC feedback in the form of a negative and a positive direct voltage, the latter one of which is coupled to the drain electrode (13) via a resistor (R7). For such a circuit arrangement (2) to provide a simple automatic calibration and equalisation of ageing-related temperature-dependent effects and an independence from component spreads in the respective transistors, particularly also in a pulse operation, a resistor (R1) of a voltage divider (R1, R2) and the base-emitter path of a bipolar control transistor (T1) are provided in parallel with the drain resistor (R7), the collector of which control transistor is connected, on the one hand, to the gate electrode of the field-effect transistor and a charging capacitor (C2) in parallel with the latter and, on the other hand, to the negative direct voltage via a resistor (R4). Furthermore, the negative direct voltage is [lacuna] essentially directly to the gate electrode of the field-effect transistor (11) via a switch device (T2) which can be controlled by means of a pulse voltage which is positive compared with the negative direct voltage... Original abstract incomplete. <IMAGE>