Abstract: Transmission-Reception Separating Filter with a PIN diode. A PIN diode is arranged in the transmission channel of the transmission-reception separating filter that has the transmission channel for forwarding a high-frequency current from a transmitter to an antenna. A rectifier is provided that generates a control current for the PIN diode from the high-frequency current flowing in the transmission channel. As a result, a separate power supply is not required for controlling the PIN diode in the transmission channel.

Abstract: In a transmitting-receiving diplexer having a transmitting channel for forwarding a radio-frequency transmission signal to an antenna connectible to an antenna terminal and having a receiving channel for forwarding a signal received from the antenna to a receiver, at least one diode is provided in the receiving channel as an RF switch. A rectifier is connected to the transmitting channel and to the diode or diodes of the RF switch, the rectifier generating a blocking voltage required for blocking the receiving channel during transmission of the transmission signal. Further, a control switch is provided that disconnects the blocking voltage from the diode or diodes of the RF switch during reception.

Abstract: A reception amplifier in a nuclear magnetic resonance system includes an input transistor. The base of the input transistor is connected to a protective circuit. The protective circuit shifts the voltage at the base-emitter path of the input transistor into the inhibit range only during a high-frequency transmission pulse. The voltage is produced by rectification of a fraction of the high-frequency transmission pulse. The protective circuit of the reception pre-amplifier prevents the input transistor from being gradually destroyed by an excessive base current during the transmission when voltage peaks are provided at the input.

Abstract: An input stage for a low-noise broadband amplifier includes a negative feedback capacitor connected between an input and an output of at least one amplifier element. The output of the amplifier element is terminated with a capacitor. The input stage has a real, constant input impedance in a broad range.