Telefonaktiebolaget Lm Ericsson (publ)

Evald Arvid Koitsalu

Lars Wallin

Michael Persson

A portable radio transceiver has a transmitter power amplifier (PA) and a series transistor (V ), which is connected to the transmitter power amplifier and is adapted, in response to a transmission control signal (TX on/off), to control transmission by the transmitter power amplifier. Negative bias generating means provides negative bias (V ) to the transmitter power amplifier and is also used for increasing a voltage applied to the gate of the series transistor so as to reduce its resistance. The negative bias generating means has a second transistor (V ) connected to the gate of the series transistor (V ), and a third transistor (V ), the gate of which is adapted to receive the transmission control signal (TX on/off) It also has a capacitor (C ) connected between the second and third transistors, and a diode means (D ) connected between the capacitor and the second transistor.

Portable radio transceiver

A memory card receptacle comprising at least one contact ( ) for electrically contacting a memory card The memory card receptacle has at least one grounding contact member for protecting electronic equipment against electro static discharge (ESD), whereat each contact ( ) is in contact with said grounding contact member when there is no memory card inserted in the memory card receptacle A portable radio communication station having SIM chip card reader according to the invention is disclosed.

ESD protecting device

A shielding device is formed by a wall having a top edge arranged to fasten a foil comprising an electrically conducting material. In order to fasten the foil, the wall can be provided with teeth at its top section. Also the wall(s) can be formed with arbitrary angles with respect to each other when forming a whole shielding device. The cover can be formed by one large or several smaller pieces. The cover is fastened to the walls by means of an adhesive, glue or soldering and an electrical contact is provided by the teeth projecting from the wall(s).

Method and a device for shielding electronic components

The present invention relates to an impedance-matching device of antenna units, and in particular to antenna-matching in small radio units. An impedance-matching device is arranged in a radio equipment having an antenna, between said antenna and a feeding unit, e.g. an output power unit, the impedance quotient of which units exceeding a factor 3. The invented impedance-matching includes at least two quarter-wave transformers connected in series, which consist of a dielectric material having a dielectric coefficient &isin;, the value of which is exceeding a factor 10. The device may be made with dimensions so small that it may be integrated with the antenna to an antenna unit and despite the small dimensions, good frequency characteristics are achieved, such as good precision, easy tuning and sufficiently broad bandwidth.

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Huddinge, Sweden

Evald Arvid Koitsalu