Nokia Mobile Phones Limited

Hannu Pakonen

Jorma Matero

Heikki Mattila

Mika Jari Tuutijarvi

Raimo Tapio Klemetti

Jorma Antero Savolainen

Eero Sakari Makikallio

The invention relates to a method and arrangement for forming a amplitude and phase modulated transmission signal. One idea of the invention is that he modulation signal is formed of separate baseband signals controlling phase and amplitude modulation. A phase control signal (phi) is used for controlling a voltage controlled oscillator ( ), from which there is further obtained a transmission frequency signal for the RF amplifier ( ). By means of the amplitude control signal (A), there is controlled the amplification of the RF amplifier. From the output of the RF amplifier, there is created a feedback signal by means of a sampling circuit ( ), and said feedback signal is used separately for correcting both amplitude control and phase control, so that the transfer function of the arrangement is made linear. Thus the employed amplifier can be a nonlinear amplifier with a high efficiency, and yet a good phase and amplitude linearity is achieved by applying the described arrangement.

Method and arrangement for forming a transmission signal

A power control loop for a radio frequency transmitter includes a power control amplifier, an output and a detector that is coupled to the output for providing an output power signal indicative of output power from the power control loop. A controller generates at least first and second reference signals. A differential amplifier provides a control output that is indicative of a difference between the output power signal and a reference signal. A dual rate filter couples the control output to the power control amplifier so as to vary its gain. The dual rate filter exhibits a fast-reacting filter mode when the controller changes the reference signals to the differential amplifier and a slow-reacting filter mode when the controller applies the first reference signal to the differential amplifier. The fast filter mode enables rapid feedback of the control output to the power control amplifier.

Dual rate power control loop for a transmitter

A dual mode transmitter with bias control is described wherein an RF signal from a system modulator is fed to a gain control circuit, which can be either a voltage controlled amplifier or attenuator. The ultimate transmitter output power level depends on the attenuation/gain of the gain control circuit. The output signal from the gain control circuit is fed to a driver amplifier which amplifies the signal and feeds it to a power amplifier circuit, which may be comprised of several stages of bipolar transistors or GaAs FETs. The modulated signal to be transmitted is then fed from the power amplifier circuit through a coupler to an antenna terminal. The coupler is connected to an RF detector and is used for RF level monitoring. The Rf level signal from the RF detector is applied to a comparator circuit. An improved combination is provided by incorporating a bias control circuit. A Vpwr signal is applied as one input to the bias control circuit and a mode signal is applied as the other input. When the mode signal is 'on' or present it signifies that the digital transmission mode is to be employed. When the mode signal is ' off' or at zero level, it indicates that the analog transmission mode is to be employed. The bias control circuit provides three bias signal outputs, V.sub.b1 applied to the driver amplifier, and V.sub.b2 and V.sub.b3, applied to the power amplifier. The levels of V.sub.b1, V.sub.b2 and V.sub.b3 are varied for the analog and digital transmission modes.

Dual mode amplifier with bias control

Disclosed is power level adjusting apparatus for a data transmission system of the type having a power amplifier means for providing a modulated output signal. A detecting circuit for providing a voltage proportional to the power amplifier means output signal level includes a coupling circuit connected to the output of the power amplifier means for coupling the modulated voltage signal therefrom to provide a detected voltage proportional to the power level of the power amplifier means modulated output voltage signal. A source of bias signal is included for selectively providing a bias signal embodied in one of two bias level states, and a switchable active device circuit is connected to the output of the power amplifier means, to the coupling means and to the source of bias signal, the switchable active device which may be a PIN diode or a GaAs FET is being responsive to the bias signal in a first one of the two bias level states for switching to a non-conducting condition and thereby providing a low signal coupling mode for the coupling means, and the switchable active device circuit is responsive to the bias signal in a second one of the two bias level states for switching to a conducting condition and thereby providing a high signal coupling mode for the coupling means.

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Oulu, Finland

Hannu Pakonen