Abstract: A cellular telephone includes a plurality of power amplifiers having a common operating region. If one of the amplifiers has to be deselected, a desired moment for the switching to another amplifier is defined based upon a predetermined transmission interrupt criterion. The power continues to be adjusted with the currently selected amplifier until the instant of switch over. Switching to the other amplifier may then be performed after the transmission has been interrupted.

Abstract: An RF power control system including a watchdog circuit for monitoring the power level of an RF signal about to be transmitted by an antenna and for monitoring the antenna beam scan angle and for adjusting and/or interrupting the RF signal in the event that the power level of the RF signal or the scan angle of the antenna beam exceed predetermined thresholds. The use of the watchdog circuit eliminates the need for stringent safety certification of a number of other subcomponents of the system and therefore significantly reduces the cost and time associated with obtaining regulatory certification of the system. In preferred forms, the watchdog circuit includes an enable input for allowing the watchdog circuit to be completely deactivated, and therefore transparent to the RF signal being generated.

Abstract: A cellular telephone receives a first communication signal from a cell-site Station and transmits a second communication signal to the cell-site station. The cellular telephone includes an antenna, a duplexer, receiver, an encoder/decoder apparatus, an acoustic transducer, a transmitter and a controller. The receiver is connected to the antenna through the duplexer. The receiver converts the first communication signal into a voice signal code, and outputs a signal indicating an intensity of the first communication signal. The transmitter is connected to the encoder/decoder apparatus and to the antenna through the duplexer. The receiver converts the input voice code Signal from the encoder/decoder apparatus into the second communication signal. The controller is connected to the receiver and the transmitter. The controller controls amplitude of the transmitter corresponding to said intensity of the first communication signal.

Abstract: An apparatus and method are disclosed for verifying the frequency of an AM carrier signal having a target frequency. The apparatus includes a high frequency clock that produces a clock signal having a higher frequency than the target frequency. A counter is advanced by the clock signal and reset after each cycle of the carrier signal. A first comparison portion compares the value recorded by the counter to a first reference value, and a second comparison portion compares the value recorded by the counter to a second reference value. An error determination portion attenuates the carrier signal if the comparisons conducted by the first and second comparison portions indicate an error condition.

Abstract: A Radio Frequency RF transmitter includes a translational loop architecture that supports non-constant envelope modulation types and includes by adjusting the envelope of the translational loop at the translational loop output. The RF transmitter includes an Intermediate Frequency (IF) modulator, a translational loop, an envelope time delay adjust block, an envelope adjust block, and a time delay calibration block. The IF modulator receives a modulated baseband signal and produces a modulated IF signal having a non-constant envelope. The translational loop receives the modulated IF signal and produces a modulated RF signal having a constant envelope. The envelope time delay adjust block receives an envelope signal corresponding to the original modulated signal and produces a time delayed envelope signal based upon a time delay control signal. The envelope adjust block adjusts the modulated RF signal based upon the time delayed envelope signal to produce an envelope adjusted modulated RF signal.

Abstract: An improved single-ended input differential pair amplifier stage comprises: 1) a first p-n-p transistor having a base terminal coupled to an input voltage; 2) a first load impedance having a first terminal coupled to a ground reference and a second terminal coupled to a collector of the first p-n-p transistor; 3) a second p-n-p transistor having a base terminal coupled to the ground reference; 4) a second load impedance having a first terminal coupled to a ground reference and a second terminal coupled to a collector of the second p-n-p transistor; 5) an inductor having a first terminal coupled to an emitter of the first p-n-p transistor and a second terminal coupled to an emitter of the second p-n-p transistor; and 6) a constant current source coupled to the emitter of the second p-n-p transistor.

Abstract: A radio frequency power amplifier circuit provides linear amplitude modulation of a radio frequency output signal while operating in a saturated amplification mode. The power amplifier circuit incorporates a lossy modulator that functions as a variable resistance responsive to an amplitude modulation signal. A supply voltage is coupled to the voltage supply input of the power amplifier circuit through the lossy modulator, such that the supply voltage applied to the power amplifier varies with the amplitude modulation signal. The radio frequency power amplifier circuit modulates the envelope of an RF output signal generated by saturated mode amplification of a constant envelope radio frequency input signal.

Abstract: A communication and/or amplifier system according to various aspects of the present invention includes an excursion signal generator and a filter system. The excursion signal generator identifies a portion of a signal that exceeds a threshold, such as a magnitude threshold. The filter system filters a corresponding excursion signal having a magnitude and waveform corresponding to the portion exceeding the threshold to remove unwanted frequency components from the excursion signal. The filtered excursion signal may then be subtracted from the original signal to reduce the peak.

Abstract: A method for operating a mobile station includes steps of (A) operating an RF transmitter power detector to obtain an output signal that is indicative of a magnitude of RF power transmitted by the mobile station; (B) processing the output signal to determine a time-varying characteristic of the output signal; and (C) determining a value of the Adjacent Channel Power Ratio (ACPR) from the time-varying characteristic. A further step uses the determined value of the ACPR to control a DC bias current, and therefore the output power capability, of a transmitter amplifier.

Abstract: A comfort noise block, that include a hangover period and comfort noise parameters, is transmitted in such a manner that it is not interrupted by other messages, such as FACCH messages. This is accomplished in a mobile station by a determination of whether any FACCH messages are required to be transmitted. If such FACCH messages exist, a further determination may be made as to which transmission can be made in the shortest time (i.e., the FACCH message or messages or the comfort noise parameters message), and this transmission is made first. In any event the comfort noise parameters block is transmitted without interruption. In a further embodiment of this invention the comfort noise parameters message is transmitted by being concatenated with another message, such as a neighbor channel measurement results message, so as to reduce overhead, conserve bandwidth, and reduce power consumption.

Abstract: A technique for peak suppressing and pre-distorting the input signal to wireless amplifiers to improve the linearity of the amplifier and subsequently significantly improving the power efficiency of the amplifier is described. The input to the amplifier, prior to being applied to the amplifier, is modified by a peak suppression and pre-distortion circuit. The peak suppression and pre-distortion circuit uses samples of the output of the amplifier to adaptively adjust a lookup table that is being used for pre-distortion. The input and output of the peak suppression and pre-distortion circuit are at the amplifier frequency. The peak suppression and pre-distortion is performed in digital domain at baseband.

Abstract: A modulating mechanism is provided comprising a first storage and a corresponding first DAC, and a second storage and a corresponding second DAC. The first storage stores an adjusted digital representation of a first waveform, while the second storage stores an adjusted digital representation of a second waveform. The adjusted representation of the first waveform is adjusted to compensate for the deviation effects experienced by the first DAC (e.g. amplitude deviation, DC offset, non-linearity, etc.). The adjusted representation of the second waveform is adjusted to compensate for the deviation effects experienced by the second DAC. In effect, the adjusted representations of the first and second waveforms cause the DAC's to exhibit the proper behavior, despite the presence of the deviation effects. By storing and using adjusted digital representations of waveforms in this manner, many benefits can be realized, including for example, eliminating the need for any analog compensation circuits.

Abstract: An apparatus and method are described for producing a test signal with a desired signal-to-noise ratio on a selectable output frequency for measuring a transmission system. A carrier signal, generated from a carrier signal, and a noise signal are remixed with the carrier signal in a bandwidth equal to or smaller than a smallest signal bandwidth of the transmission system. The levels of the carrier signal and the noise signal are adjusted to a predetermined ratio based on a measurement of the remixed carrier signal and the remixed noise signal. The noise signal is attenuated and added to the carrier signal until the desired signal-to-noise ratio is attained.

Abstract: A method to reduce crossmodulation in a multimode radio communication device with a transmitter, a receiver, and a second receiver (400) that operates in a receiver channel bandwidth (402) includes a step of measuring a first signal strength in the receiver channel bandwidth (404), a second signal strength outside of the receiver channel bandwidth (406), and a power level of the transmitter. A next step (408) includes determining a signal-to-crossmodulation interference ratio (SCMIR). A next step (410) includes calculating a SCMIR threshold. A next step (412) includes comparing the ratio to the threshold.

Abstract: A multi-channel transmission system and method provide peak power smoothing without additional in-band interference. The system includes a multi-carrier waveform generator for reducing peak amplifier power required to transmit a digital multi-carrier waveform based on a plurality of digital carrier waveforms. A signal conversion system generates an analog multi-carrier waveform based on the digital multi-carrier waveform. The analog multi-carrier waveform has a center frequency and a desired gain over the original signal. A bandpass filter is coupled to the signal conversion system for restriction of the analog multi-carrier output waveform to a desired transmission bandwidth. The multi-carrier waveform generator has a nulling waveform generator coupled to a plurality of single carrier waveform modules for generating a digital nulling waveform based on the retrieved data. The nulling waveform reduces a peak power of the multi-carrier waveform and results in a reduced signal envelope.

Abstract: Digital modulator 101 digitally modulates a transmission data. Modulation signal decision section 102 decides whether a peak power is occurred from transition of signal point of this modulation signal. Control signal generator 103 outputs a phase-shifted phase control signal when it is decided based on the decision result that peak power was occurred and outputs a non-phase-shifted phase control signal when it is decided based on the decision result that peak power was not occurred. Phase controller 104 changes the phase of a modulation signal using the control signal outputted from control signal generator 103. Filter 105 limits the bandwidth of the modulation signal outputted from phase controller 104. Orthogonal modulator 106 modulates the modulation signal outputted from filter 105.

Abstract: A power amplifying apparatus for a mobile phone is provided. In the power amplifying apparatus, a power amplifier uses a transistor as a power amplifying device, and a non-volatile memory pre-records the static characteristic measurement data of the transistor. A DC bias current of the transistor is controlled according to transmission power of the power amplifier referring to the static characteristic measurement data, by changing a gate voltage of the transistor, by changing a drain voltage of the transistor with the gate voltage fixed, or by changing both the gate voltage and the drain voltage.

Abstract: A balanced power amplifier for radio frequencies. The power amplifier may be switched from operating in a saturation mode, so that AMPS-type radio telephone signals may be optimally amplified, to a linear mode so that CDMA signals may be amplified. A directional coupler splits an input signal into quadrature signal components which are supplied to the input of a pair of dual mode power amplifiers. The output signals from the dual mode amplifiers are recombined in a directional coupler. The directional coupler effectively applies all of the output power to an antenna connected to one of the coupler ports, and effectively isolates the output stages of the amplifiers from any reflected power generated by the antenna.

Abstract: The pulse-shaping look-up table with transient suppression (530) avoids hard turn-on and turn-off transients by modifying word segments of initial and final digital words during transmission of a digital data sequence. A controller (570) sends a mode signal and a digital data sequence to the pulse-shaping look-up table with transient suppression (530). A mode buffer and command block (560) uses the mode signal to control the creation of initial and final digital words created by a data buffer and control block (550) from the digital data sequence. The digital words are used by a look-up table (540) to create a sampled digital output waveform sequence. The pulse-shaping look-up table with transient suppression (530) provides an accurate output waveform sequence with reduced spectral emissions even during start-up and shut-down of digital data transmissions.

Abstract: This invention relates to power detectors as employed in electrical circuits in general. The invention also relates to power detectors associated with high power amplifiers and, in particular, but not exclusively, relates to power detectors associated with telecommunications high power and high frequency power amplifiers. The present invention further provides apparatus and methods of switching amplifier blocks. The present invention seeks to provide an improved power detector having an increased range. In accordance with a first aspect of the invention, there is provided a radio frequency power detector, which detector comprises a radio frequency coupler, a radio frequency to direct current voltage converter and an operational amplifier circuit to provide voltage scaling; wherein the operational amplifier circuit includes a plurality of amplifiers operable to amplify the dc signals. The amplifiers can be switched into operation under microprocessor control or by diode switching.

Abstract: 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 (RFOUT) of an RF time division TDMA signal (RFIN), 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 (VCTRL).

Abstract: A polar loop based radio telecommunication apparatus which has a phase control loop for controlling the phase of a carrier outputted from an oscillator for transmitter, and an amplitude control loop for controlling the amplitude of a transmission output signal outputted from a power amplifier circuit, wherein precharge means is provided on a forward path from a current source, through the power amplifier circuit, to a detection circuit, forming the amplitude control loop, for rapidly increasing a control voltage for the power amplifier circuit to a power threshold upon starting transmission.

Abstract: A Radio Frequency RF transmitter includes a translational loop architecture that supports non-constant envelope modulation types and includes by adjusting the envelope of the translational loop at the translational loop output. The RF transmitter includes an Intermediate Frequency (IF) modulator, a translational loop, an envelope time delay adjust block, an envelope adjust block, and a time delay calibration block. The IF modulator receives a modulated baseband signal and produces a modulated IF signal having a non-constant envelope. The translational loop receives the modulated IF signal and produces a modulated RF signal having a constant envelope. The envelope time delay adjust block receives an envelope signal corresponding to the original modulated signal and produces a time delayed envelope signal based upon a time delay control signal. The envelope adjust block adjusts the modulated RF signal based upon the time delayed envelope signal to produce an envelope adjusted modulated RF signal.

Abstract: A Radio Frequency RF transmitter includes a translational loop architecture that supports non-constant envelope modulation types and includes by adjusting the envelope of the translational loop at the translational loop output. The RF transmitter includes a phase equalizer, an Intermediate Frequency (IF) modulator, a translational loop, an envelope time delay adjust block, an envelope adjust block, and a time delay calibration block. The phase equalizer receives a modulated baseband signal and phase equalizes the modulated baseband signal to produce a phase equalized modulated baseband signal. The IF modulator receives the phase equalized modulated baseband signal and produces a modulated IF signal having a non-constant envelope. The translational loop receives the modulated IF signal and produces a modulated RF signal having a constant envelope.

Abstract: Angle-modulated signals are transmitted in a communications system, in which coding information has been inserted into the transmitted data at regular intervals. The coding information is phase-modulated together with the transmitted data. This coding is used for pulse shaping, so that the receiver can recover the digital transmitted data with less implementation complexity and without carrier phase control by using appropriate signal processing.

Abstract: A method of operating a Time Division Multiple Access (TDMA) communication system is disclosed. The system includes a multi-carrier power amplifier. The method includes the steps of logging call activity on each timeslot of each carrier associated with the multi-carrier power amplifier; logging total transmit power of the multi-carrier power amplifier for each timeslot; and logging the data rate of any data calls being carried by the multi-carrier power amplifier. Transmission power is made available for a new call by reducing the transmission power of a data call.

Abstract: A transmitter (200) has a compression detector for sensing the level of compression (110) in a signal that is being transmitted. The transmitter also has a radio frequency power amplifier (RFPA) (414) that is supplied by a supply modulator (426). The supply modulator provides a dynamic supply bias to the RFPA to maintain a desired amount of compression in the signal being transmitted. The supply modulator is responsive to a modulation signal (207) created by substantially following the envelope (214) of the signal to be transmitted (212). However, various signal and operational conditions can occur which cause the compression level to deviate (506) from the desired level. To maintain the desired compression level, the compression detector provides an output that is used to adjust the modulation signal from following the envelope of the signal to be transmitted in an unadjusted manner.

Abstract: The invention relates to a method for generating an amplitude-modulated transmission signal with an adjustable average transmission capacity. An amplitude modulation signal is applied to an input of a transmission amplifier and regulated using a part of the transmission signal that is fed back. The fed-back part of the transmission signal is attenuated for regulation, according to the desired average transmission capacity.

Abstract: A peak limiter for use in a system for amplifying a multi-carrier signal receives a baseband signal of each carrier of the multi-carrier signal. The multi-carrier signal is computationally estimated to have carriers combined in an RF band, and obtains power information of the multi-carrier signal to limit an amplitude of the baseband signal based on the power information of the estimated multi-carrier signal to thereby provide peak-limited baseband signals. Thus, the distortion generated by performing the unnecessary peak limitation can be effectively prevented to thereby improve the reliability of the entire system.

Abstract: A code division multiple access (CDMA) mobile communication system for controlling power for a traffic signal of one frame includes: a signal generator for simultaneously generating a pilot signal and the traffic signal on a frame basis; a power compensator for compensating the power of the traffic signal according to a punctured length of a punctured frame among the frames; and a signal combiner for combining the power-compensated traffic signal and the pilot signal generated from the signal generator.

Abstract: There is disclosed a single-ended input differential pair amplifier stage. The single-ended input differential pair amplifier stage comprises: 1) a first n-p-n transistor having a base terminal coupled to an input voltage; 2) a first load impedance having a first terminal coupled to a power supply and a second terminal coupled to a collector of the first n-p-n transistor; 3) a second n-p-n transistor having a base terminal coupled to a ground reference; 4) a second load impedance having a first terminal coupled to the power supply and a second terminal coupled to a collector of the second n-p-n transistor; 5) an inductor having a first terminal coupled to an emitter of the first n-p-n transistor and a second terminal coupled to an emitter of the second n-p-n transistor; and 6) a constant current source coupled to the emitter of the second n-p-n transistor.

Abstract: An improved filter amplifier for wireless cellular communication is provided. The filter amplifier comprises a talk-in and talk-out booster. The booster utilizes a single local oscillator to down-convert a received signal for filtering and up-convert the received signal for further amplification. The oscillator is programmable and the oscillator determines the frequency that each booster filters. A combining unit including amplifier and isolator is operable to receive the filtered signal and amplify and combine the signal. The use of isolators allows for combining signals without interference. The booster amplifier filter unit is designed for use in boosting only certain frequencies in a wide band frequency range.

Abstract: The invention relates to a transmission or transmission/reception device having a transmission path structure which makes it possible to increase the range of variation of the transmission power without degrading the signal-to-noise ratio. The attenuation is achieved in part in an internal unit 5 and in part in an external unit 4 with the aid of a switching circuit 25 which short-circuits or otherwise the amplifier 20 of the antenna 21.

Abstract: A MOSFET amplifier includes a pre-amplifier stage and a power amplifier stage. The pre-amplifier is a CMOS inverter having a signal output that is DC connected to the gate of a MOS. control transistor of the power amplifier stage. The CMOS inverter includes an NMOS transistor with a source connected through an inductor to ground and a drain to the source of a PMOS transistor. The drain of the PMOS transistor is connected through another inductor to a supply voltage. The gates of the NMOS and PMOS transistors are connected to both receive an input signal of the amplifier.

Abstract: Disclosed is a mobile communication terminal which is provided with an equalizer function of audio equipment to adjust a timbre of transmitting/received speech sounds so as to satisfy a great number of users having various individualities and tastes simultaneously. The mobile communication terminal according to the present invention includes an equalizer connected to a CODEC, a speaker and a microphone for adjusting a timbre of an analog speech signal inputted thereto from the CODEC and/or a speech signal inputted thereto through the microphone, and an equalizer control circuit for controlling a timbre control operation of the equalizer according to a control signal of a CPU.

Abstract: A method for operating a base station employing a CDMA technique comprises combining a plurality of spread spectrum data signals into a combined signal having a fluctuating power level corresponding to the data signals; modulating the combined signal to produce an RF signal; measuring average power of the combined signal over a selected time period; adaptively limiting the combined signal power to a calculated level based at least in part on the measured power; and transmitting the RF signal.

Abstract: A cellular telephone includes a plurality of power amplifiers having a common operating region. If one of the amplifiers has to be deselected, a desired moment for the switching to another amplifier is defined based upon a predetermined transmission interrupt criterion. The power continues to be adjusted with the currently selected amplifier until the instant of switch over. Switching to the other amplifier may then be performed after the transmission has been interrupted.

Abstract: A method of controlling the power delivered by a heterojunction bipolar transistor power amplifier receiving an input power and delivering an amplified output power in a zero intermediate frequency architecture includes a step of detecting the output power and varying a control voltage of the power amplifier by means of a control loop and a step of varying the input power level of the power amplifier.

Abstract: An automatic and adjustable power control method and apparatus for optimally controlling the output power of a CDMA handset is provided. The method and apparatus utilize a single control signal to automatically control the gain of two frequency diverse variable gain stages of a transmitting portion of the handset by a multi-point hand-off technique. The multi-point hand-off technique partially varies the gain of a first stage to satisfy key system constraints and hands-off control to a second stage. The gain of the second stage is varied to satisfy additional system constraints. A second hand-off is performed so that the gain of the first stage may be varied again to maintain the optimal power control.

Abstract: The invention relates to transmitting power control equipment for controlling the level of a transmission wave at the transmitting end of a radio transmission system and transmitting equipment incorporating this transmitting power control equipment. In the radio transmission system to which the invention is applied, the gains of amplifiers disposed individually in a pre-stage and a subsequent stage of means for executing frequency conversion in a transmission wave generation process are kept at suitable values with respect to a level at which the transmission wave is to be transmitted, and are properly updated. Therefore, transmission quality can be highly maintained over a broad dynamic range of transmitting power to be set, in comparison with prior art equipment.

Abstract: A test method in an RF communication system is described. In the communication system, at least one RF communication channel lies about a known carrier frequency in an RF communication band. According to the method, a diagnostic signal is introduced into a circuit to be tested, such as a linear power amplifier, the diagnostic signal having an RF diagnostic frequency lying within the communication band. The diagnostic signal is down converted to an intermediate frequency for diagnostic purposes so that DSP is simplified. The diagnostic frequency is selected based on the known carrier frequency of the communication channel so that the communication channel is not down converted as an image band with the diagnostic signal. A transmitter and an alternative test method are also described.

Abstract: A transmitter (2) for communication devices according to the invention comprises a high-frequency power amplifier for amplifying the high-frequency signal to be transmitted, which high-frequency power amplifier includes an output stage for giving an amplified high-frequency signal, and measuring devices for measuring the power (Pdc) of the high-frequency signal. The measuring devices comprise devices (A1, RECT1, INT1, A2, RECT2, INT2) for measuring the voltage (VCE) and current (IE) of the high-frequency signal in said output stage, and means (M1, INT3) for calculating the power of the high-frequency signal on the basis of the measured high-frequency voltage (Vmeas) and high-frequency current (Imeas). A mobile station (1) according to the invention has a transmitter (2) for transmitting signals, which transmitter (2) includes a high-frequency power amplifier for amplifying the high-frequency signal to be transmitted.

Abstract: When transmission power control bit data is transmitted from a base station, a transmission power control circuit controls the transmission power of a transmitting amplifier and the transmission power on-off ratio according to the transmission power control bit. That is, the mean transmission power is determined according to the transmission power control bit data. At this time, the transmission “on” time ratio is reduced as much as possible according to: (mean transmission power)=(transmission power when transmission is “on”)×(transmission “on” time ratio), and (transmission power when transmission is “on”) (transmission power when transmission is “on”) (maximum transmission power of transmitting amplifier).

Abstract: A method for automatically changing transmission power of a three-sector base station in a mobile communication system is disclosed. The mobile communication system includes a base station manager (BSM) and a base station having a base station control processor (BCP), a plurality of RF Up-converters and a memory. In the method for automatically changing the transmission power of three-sector base station in accordance with the present invention, the optimal transmission attenuation values for multiple CDMA channels in each sector are detected at the three-sector base station and set to the corresponding RF Up-converters. Therefore, the detection and setting of the optimal transmission attenuation values for multiple CDMA channels are simply performed, thereby reducing time and cost for the detection and setting. Also, in the present invention, the cell-plan device is not necessary, which reduces expense to detect the optimal transmission attenuation values.

Abstract: An apparatus and method to use the temperature of a transmitting radio to prevent transmission of radio waves outside of an assigned frequency band. More specifically, if a transmitter exceeds a specified temperature the transmitter will be automatically disabled to prevent temperature caused frequency shifts outside the approved frequency transmission band for the transmitter. The transmitter has a temperature sensor that senses temperature and compare the operating temperature against a preselected temperature limit. It the operating temperature either is too hot or too cold the transmitter will be disabled and will not transmit until the temperature falls or rises to an acceptable level.

Abstract: When an installed wireless remote unit is operating in the field, routine operation is interrupted to enter a calibration mode. In calibration mode, the compression point of a circuit element is determined by applying a series of different drive levels to the circuit element. Based upon the determination of the compression point, a maximum transmission point is selected for the remote unit. Upon resumption of normal operation, the remote unit uses the maximum transmission point to limit the signal power level transmitted over the wireless link. As time passes or operating conditions change, the calibration process is re-executed.

Abstract: Radio frequency transmitters and transmitting methods control amplification of a radio frequency power amplifier, attenuation of a voltage standing wave ratio (VSWR) attenuator, and attenuation of a power control attenuator, in response to power control signals. Wide ranges of power control, for example up to 60 dB or more, may thereby be provided without unduly increasing transmitter complexity or power consumption.

Abstract: Correction/controlling of amplitude errors in radio transmission is by application of negative feedback to mixer plus power amplifier stages. Incoming signals to the mixer, typically from RF exciter or IF stage, have a modulating envelope. Envelope of mixer modulated carrier signals from the amplifier is detected and applied in anti-phase as negative feedback to the mixer input.

Abstract: An attenuator unit for attenuating a signal, the unit includes a &pgr;-type attenuator having a first resistor and second and third resistors which are arranged on both sides of the first resistor, a first transistor connected in parallel with the first resistor, and a second transistor connected between a joint node of the second resistor and the third resistor and a first voltage level. In the unit, by controlling a gate voltage of the first transistor and a gate voltage of the second transistor, an attenuation value of the attenuator unit is changed.

Abstract: A communication device employs a method and apparatus for amplifying a radio frequency (RF) signal that eliminates the need for a signal splitter. An RF input signal (202) is coupled to a first RF amplifier stage (206) only. A signal coupler (222) couples an output of the first amplifier stage (206) to an input of a second amplifier stage (208). The input signal (242) for the second RF amplifier stage is an attenuated version of the output signal (240) from the first RF amplifier stage. The outputs of the first and second RF amplifier stages (206, 208) are combined by a signal combiner (234) to produce a combined output signal (246) for transmission.