Abstract: The invention relates to an arrangement for securing the SIM card (6) in a mobile telephone. By means of the arrangement according to the invention the SIM card (6), which is normally held in place by the spring force exerted by a spring (11) attached to the battery (10) of the telephone, will remain in place while the battery (10) is in place and also while the battery (10) is being removed from the mobile telephone frame (1). This is accomplished by including in the telephone frame a protrusion (8), behind which the SIM card (6) is locked as a result of said spring force. The arrangement according to the invention can advantageously be applied to portable mobile telephones with SIM cards (SIM, Subscriber Identity Module).

Abstract: A scaling circuit in which a signal, which contains an ambient offset portion and a desired signal portion, in current mode, is scaled using a resistance means. The offset portion is substantially eliminated using constant flow rate means in the form of a current mirror, thus enabling the entire scaling dynamic of the circuit to be utilized. The teaching of the invention is directed in particular to the elimination of an error signal component from a Received Signal Strength Indicator (RSSI) signal that is output from a radio frequency receiver, such as a radiotelephone receiver.

Abstract: A circuit arrangement in which an RF amplifier circuit also acts as a filter for a second supply voltage which is produced from the supply voltage (V.sub.cc out) of the amplifier. The high frequency RF amplifier circuit comprises a common emitter transistor with ancillary components, and the emitter is connected through a capacitor to the ground of the circuit. From the emitter of the transistor is obtained the second supply voltage (V.sub.cc out) in which the filter circuit is said high frequency amplifier circuit wherein the transistor is used as an emitter follower. With the circuit arrangement of the invention, the separate high frequency amplifier circuit and the filtering circuit of the second supply voltage, both known of prior art, can be combined.

Abstract: Balanced mixers with respect to their output stages are created by making the differential mixer output (A, B) a single-ended output (C) without a matching transformer. The circuitry can be used in all balanced transistor mixers, provided that both sides of the differential output are available for use.

Abstract: Circuitry for compensating for the temperature drift of a phase detector (1) in a phase-locked loop which comprises a phase detector (1), a loop filter (2) and in the feedback branch a voltage controlled oscillator (3) coupled to the phase detector (1). The phase detector (1) is provided with a differential output (I and II), which is coupled to the input terminals (- and +) of the operational amplifier (4) in the loop filter (2), whereby the common-mode temperature drift of the phase detector (1), appearing in the input poles of the operational amplifier, is substantially eliminated in the output of the amplifier (Uout).