Nokia Mobile Phones Limited

Simo Murtoj&auml;rvi

Harri Kimppa

Antti Rauhala

The object of the invention is the compensation of the drift in a detector and a control signal (TXC), particularly in the control of the transmit power (RF ) of an RF time division TDMA signal (RF ), for the control of which there is performed a power detection. According to the invention the voltage difference between the output voltage of the detection and the control signal is stored during a transmission pause, and during the transmission state the stored voltage difference is used to compensate the temperature drift of the detection and the control signal (TXC) in generating the gain control voltage (V ). The voltage difference is stored in a capacitor connected between the detector and a feedback connected differential amplifier by connecting the inputs of the differential amplifier to each other and by connecting the output of the differential amplifier to a constant potential when the control signal (TXC) is connected to an input of the differential amplifier which is not that input to which said capacitor is connected. Also alternative ways to perform the storage are presented.

Method and an arrangement for compensating the temperature drift of a detector and a control signal in periodic control

The invention relates to a bandpass filter that follows the frequency of an input signal especially for reducing the noise on the receive band of mobile communications devices. More specifically the invention relates to a method and arrangement for tuning a resonator (100), where an input signal feeds the resonator in such a manner that the resonator oscillates at, the frequency of the input signal, and where the center frequency of the pass band of the resonator is set substantially to the frequency of the input, signal. In accordance with the invention, there is generated (200) a difference signal (V , V ) proportional to the phase difference (&Dgr;&phgr;) between the input signal voltage (V ) and resonator voltage (V ) and the resonance frequency of the resonator is changed using the difference signal in such a manner that said phase difference becomes smaller. Using the invention, the resonance frequency of the resonator can be set relatively accurately to the input signal frequency because the phase characteristic of the resonator is at its steepest at the resonance frequency, whereby the phase difference detector reacts strongly on even the slightest changes in frequency.

Method and arrangement for tuning a resonator

The invention relates to a method and radio receiver for attenuating spurious signals when receiving ( to ) radio signals, when radio signals are mixed ( ) to a second frequency, which may be the baseband frequency, for example. Spurious signals are caused by balance errors in the mixer ( ) which result from component value fluctuations within tolerance limits. According to the invention, mixing is balanced by setting ( ) variable-level bias voltages and/or currents to transistors in the mixer circuit ( ). An advantage of the invention is that even-order spurious signals caused by balance errors in the mixing of a signal to a second frequency are considerably attenuated. The invention finds particular utility in a mobile communications device, for example.

Method for attenuating spurious signals and receiver

The active component (,) of a radio device comprises a first transistor (Q,) and a second transistor (Q,). The differential input of the active component comprises a first input line (RF&plus;) and a second input line (RF&minus;), of which the first input line is coupled to the base of the first transistor (Q,) and the second input line is coupled to the base of the second transistor (Q,). In order to match the input impedance there is cross-feedback (Rfb&prime;) between the first transistor (Q,) and the second transistor (Q,).

Growing community of inventors

Salo, Finland

Simo Murtojärvi

Growing community of inventors

Salo, Finland

Simo Murtoj&auml;rvi

Simo Murtojärvi