Nokia Mobile Phones Limited

Nokia Corporation

St-ericsson Sa

Mokia Mobile Phones Ltd.

Jorma Matero

Heikki Mattila

Jaakko A Hulkko

Jussi Vepsäläinen

Matti I Kangas

Mikko Veijo Halttunen

Marko Alanen

Niall Eric Shakeshaft

Toivo Vilmi

Hannu Pakonen

Jaako Maunuksela

Kjell I Ostman

Kari Kananen

Tapio Rautava

Jarkko Kesti

Erkki Tiittanen

Problems arising from a pre-emphasis filter, particularly an infinite-impulse-response filter, in a signal modulator are solved by detecting sequences of the same bit or symbol in a modulation signal and compensating the corresponding d.c. offset in the signal generated by the pre-emphasis filter without real-time feedback. The amount of offset compensation can be defined during design of the modulator or adjusted or calibrated during production. It is not necessary to change the transfer function of the pre-emphasis filter, but only to correct the d.c. offset of the filter output signal.

Filter offset compensation

A transmission signal to be transmitted from a radio transmitter is predistorted in order to compensate for the signal distortion caused by a power amplifier. The transmission signal and a signal modeling a power supply voltage applied to the power amplifier are compared with distortion properties of the power amplifier using these signals. The distortion information is comprised in an amplitude distortion lookup table and a phase distortion lookup table. Transmission signal and power supply signal values are associated with envelope and phase predistortion information comprised in the respective lookup tables and the envelope and the phase of the transmission signal is predistorted accordingly.

Signal predistortion in radio transmitter

A method and device for improving the efficiency of an envelope tracking transmitter in which a power amplifier for coupling modulated signals in a carrier frequency to an antenna for transmission. The transmitter comprises a power supply for providing a supply voltage to the power amplifier, and a computation means for providing a waveform indicative of the envelope of the modulated signal to the power supply in order to modify the supply voltage. A lower limit is imposed to the waveform so that the supply voltage to the power supply is always greater than a predetermined value. Moreover, when information is transmitted in times slots which are started and ended by ramp periods, a constant signal, based on the root-mean-square value of the waveform, is used to modify the waveform so that the supply voltage to the power amplifier includes a constant voltage level in the ramp periods.

Waveforms for envelope tracking transmitter

A radio frequency modulator based on direct frequency/phase modulation of output signal of a controllable oscillator () that is a part of a phase locked loop (PLL) provides a direct modulator that is able to operate over a wide frequency range with a flat frequency response. A modulation signal is digitally processed () before injection to a high-pass path of a direct modulator. Applicability of digital signal processing is based on the fact that the modulation signal is a base band signal. Therefore, the modulation signal () occupies such a band in the frequency domain so that a sufficient ratio of a sampling rate to an upper edge frequency of the modulation signal can be achieved. Digital processing is used for compensating an effect of non-flat high-pass PLL transfer function and/or to perform pre-distortion of the input signal of a controlled oscillator to compensate an effect of non-linearity of a controlled oscillator.

High pass modulation of a phase locked loop

A test signal comprising a periodic waveform, such as a triangular waveform and sawtooth waveform, is used for propagation delay matching in a transceiver front-end. The test signal is separately fed to the envelope path and the RF path. At the power amplifier stage, a phase modulator is used to obtain the envelope signal and the phase modulated RF signal for demodulation by an IQ demodulator. At the output end of the IQ demodulator, the I-signal is measured while the delay block is adjusted in order to vary the propagation delay. When the propagation delay matching is correct, the peak-to-peak value of the I-signal is a minimum. Preferably, during calibration using the test signal, the transmitter RF power amplifier is disabled so that no spurious signals will be sent. The transmitter can be an EDGE polar transmitter, a non-EDGE transmitter or a EER polar transmitter.

Method and system for transmitter envelope delay calibration

The invention relates to optimizing efficiency of a power amplifier of a transmitter. In a solution according to the invention a detected envelope () of an input signal of the power amplifier is filtered with a non-linear filter () that substantially preserves a rise time of a peak in a waveform of the envelope but lengthens a temporal duration of the peak. A filtered envelope is used as an input quantity () for a control system that controls a supply voltage of the power amplifier. For the control system it is easier to react to peaks of the filtered envelope than to the peaks of the envelope because the temporal duration of the peaks of the filtered envelope is longer than that of the peaks of the envelope.

Method and arrangement for optimizing efficiency of a power amplifier

An RF transceiver having dual-mode envelope restoration architecture. In narrow-band applications such as GSM/EDGE, a switch-mode amplifier is used to provide an envelope signal for amplitude modulating the phase-modulated signals. To achieve required modulation bandwidth in wide-band applications such as WDCMA, an analog amplifier is used to provide the envelope signal. Furthermore, in the wide-band mode, the envelope modulation is applied through the base of an emitter follower while the collector voltage is scaled to achieve a desired power output in the amplitude-modulated signals.

Multi-mode envelope restoration architecture for RF transmitters

A dual band user terminal (,) includes a controller (,) for outputting a BAND signal for specifying operation in one of a first frequency band or a second, higher frequency band; a single frequency synthesizer (,) that is responsive to the BAND signal for outputting an RF signal in one of two frequency bands; and an RF transceiver (,) comprising a dual band receiver that receives RF signals in the first frequency band and in the second, higher frequency band, and a dual band transmitter that transmits RF signals in the same frequency bands. The dual band receiver includes a first receiver chain that operates in the first frequency band as a single conversion receiver having a downconversion mixer that is preceded by a first filter and that is followed by second filter, and a second receiver chain that operates in the second frequency band as a dual conversion superheterodyne receiver having a first downconversion mixer preceded by a first filter and followed by a second filter coupled to a second downconversion mixer followed by a third filter. The downconversion mixer of the single conversion receiver is also the second downconversion mixer of the dual conversion superheterodyne receiver, and the second filter of the single conversion receiver is also the third filter of the dual conversion superheterodyne receiver. The dual band transmitter includes a modulator that outputs a modulated RF signal. When operating in the first frequency band the input RF signal to the modulator has a frequency that is equal to the transmitted RF signal, and when operating in the second frequency band the input RF signal has a frequency that is equal to one half of the transmitted RF signal.

Dual band architectures for mobile stations

This invention teaches methods and apparatus for providing a low cost, low complexity, and low component count transmitter feedback function for use in mobile station transmitter linearization and self-test operations. Disclosed is a method for operating a mobile station of a type that includes a transmit chain having an output coupled to an antenna and a receive chain having an input coupled to the same or a different antenna. The method includes steps of: during a transmission time, (a) sampling an amplified signal prior to the amplified signal being applied to the antenna for transmission from the transmit chain; (b) downconverting a frequency of the sampled amplified signal to a lower frequency signal using a receive chain local oscillator signal normally used for downconverting a received signal to the first IF; and (c) demodulating the lower frequency signal to a baseband signal with a receive chain demodulator by using a second local oscillator signal that is normally used as a transmit chain modulator injection frequency signal. A further step of the method determines from the baseband signal an amount of predistortion of an input signal to the transmit chain in order to obtain a desired amount of linearization of the amplified signal.

Dual band architectures for mobile stations having transmitter

Disclosed are various embodiments of circuitry for coupling first and second transceivers of a dual band radio telephone to integral and external antennas. The circuitry uses impedance matching lengths of transmission lines and switches arranged to provide a minimum insertion loss. Also disclosed is an embodiment for use with a single band radio telephone, such as a digital TDMA radio telephone that either transmits or receives at any given time. Also disclosed is an antenna switching arrangement for a dual band phone that eliminates a requirement for duplexers.

Antenna switching circuits for radio telephones

A dual band user terminal (10) includes a controller (18) for outputting a BAND signal for specifying operation in one of a first frequency band or a second, higher frequency band; a single frequency synthesizer (46) that is responsive to the BAND signal for outputting an RF signal in one of two frequency bands; and an RF transceiver (11) comprising a dual band receiver that receives RF signals in the first frequency band and in the second, higher frequency band, and a dual band transmitter that transmits RF signals in the same frequency bands. The dual band receiver includes a first receiver chain that operates in the first frequency band as a single conversion receiver having a downconversion mixer that is preceded by a first filter and that is followed by second filter, and a second receiver chain that operates in the second frequency band as a dual conversion superheterodyne receiver having a first downconversion mixer preceded by a first filter and followed by a second filter coupled to a second downconversion mixer followed by a third filter. The downconversion mixer of the single conversion receiver is also the second downconversion mixer of the dual conversion superheterodyne receiver, and the second filter of the single conversion receiver is also the third filter of the dual conversion superheterodyne receiver.

A diplexer for coupling plural electronic circuits to a common antenna, wherein the antenna has at least a portion which is in the shape of a rod. The diplexer includes a set of dielectric sleeves encircling the rod-shaped portion of the antenna. The diplexer is constructed of plural branches, each of which has a filter for passing signals in a portion of the spectrum different from the portions of the spectra passed by other ones of the branches. Inductors and capacitors employed in respective ones of the branches are formed by electrical elements disposed on surfaces of the sleeves. Such elements include bands of electrically conductive material which serve as plates of capacitors, and elongated conductive strips which serve as inductors. Resistive material may also be placed on surfaces of the sleeves for construction of resistors of the branches in the event that such resistors are required in the electrical filtering. In the case of a portable electronic component, such as a radiotelephone having a housing with an antenna extending therefrom, the construction of the diplexer provides for a compact configuration enabling use of the diplexer without enlargement of the housing and without inconvenience to a user of the radiotelephone.

Antenna mounted diplexer

A circuit is provided for use in a dual mode mobile phone for selectively one of phase modulating or frequency modulating an RF signal. The circuit includes an IQ generator for generating one of first quadrature waveshapes or second quadrature waveshapes in response to a modulating signal; a quadrature mixer for mixing the first quadrature waveshapes or the second quadrature waveshapes with an RF signal to generate a phase modulated RF signal or a frequency modulated signal, respectively; and a limiter, such as at least one limiting amplifier, that has an input coupled to an output of the quadrature mixer for reducing an amplitude modulation component of only the frequency modulated signal. The at least one limiting amplifier has an input coupled to a limit control signal that has a magnitude selected for setting a dynamic range of the at least one limiting amplifier. The phase modulated signal may be a .pi./4-DQPSK signal. This invention also teaches an analog mobile phone that employs the IQ modulator and limiter to generate a FM transmission signal, and that furthermore requires but a single variable local oscillator that is used to quadrature mix and up-convert the transmitted FM signal, and that is also used to down-convert a received FM signal to an IF signal. The IF signal has a frequency equal to the channel spacing between the transmitted and received FM signals, or 45 MHz in an analog mobile phone embodiment compatible with IS-91.

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Oulu, Finland

Jorma Matero