Abstract: Transmitter including a controllable power amplifier, whose output signal is fed back to a control input of the power amplifier via a detector device which produces a detector signal for detecting the output power of the power amplifier, and comprising a signal generator for producing a control signal which is used for forming the output signal and has rising and falling edges. A control signal is derived from the comparison of the detector signal with the reference value which control signal has a rising edge and thus also terminates the increase of the transmitted power. The transmitter is used in time-division multiplex systems, more specifically, in mobile and fixed stations in a mobile radio system according to the GSM standard.

Abstract: A communications device in which a control unit and a delay unit transmit a time-shifted acknowledge signal in response to a received message. For the purpose of adhering exactly to the difference in time between receiving the request signal and sending the acknowledge signal, the control unit is connected to a temperature sensor and an adjustment-value memory. By means of the temperature sensor the control unit takes an adjustment value from the appropriate memory address and passes this adjustment value to the delay unit for determining the delay time. A field of application is, for example, mobile radio receivers for car telephone systems.

Abstract: In order to provide brightness-dependent control of a lamp which is used for illuminating a LCD display, it is known to switch the lamp on and off in dependence on the measured brightness of the incident ambient light. To prevent overheating of the liquid crystal display when it is, for example, exposed to direct sunlight, the operating voltage for the lamp is changed in dependence on the measured brightness of the incident ambient light. A further improvement is accomplished when, additionally, in dependence on the ambient temperature measured, the operating voltage for the lamp changes, more specifically the operating voltage is switched off when a presettable threshold value is exceeded. The circuit arrangement for performing the method requires very little design effort and cost and is integrable to a very large degree.