Abstract: A predistortion linearizer for microwave power amplifiers has a linear channel and a non-linear channel. Both channels are made up of the same units. Each channel includes a variable phase-shifter, a variable attenuator and an amplifier. Each channel can further include a fixed attenuator. The two channels are coupled at their ends by couplers each introducing a phase-shift of 90.degree. so that the total phase-shift is 180.degree.. Because the components of the two channels are the same, any variations with the frequency or the amplitude of the signal or with the operating temperature cancel out. The linearizer has applications in telecommunications and in particular in multicarrier systems.

Abstract: A dual-gate field effect transistor attenuator wherein a variable active load (1) is applied to the second gate of the dual-gate field effect transistor (T1). The attenuator is particularly suitable for space telecommunications.

Abstract: A limiter circuit having a field effect transistor whose bias circuit is constituted by two constant voltage feeds: one for its gate and the other for its drain, with a resistive load being connected in series with the feed to the gate of the transistor. The invention is particularly applicable to space telecommunications.