Abstract: An apparatus, method and computer program, the apparatus including: a modulator including a first input for receiving a data signal and a second input for receiving an output signal from a phase locked loop wherein the modulator is for modulating the output signal from the phase locked loop using the data signal and providing the modulated signal to an output for connection to an amplifier; and a phase shifter configured to result in a predetermined phase shift to the modulated signal.

Abstract: A new pulse shape for CPM is introduced which is obtained by a linear combination of well-known RC and REC pulse shapes. The new pulse shape addresses the tradeoff between the width of the PSD main lobe and the rate of decay of the side lobe to improve the coded performance of multi-carrier systems affected by ACI. Also, a methodology is proposed to design and evaluate the performance of the new pulse shape for multi-carrier, coded systems based on the modulation constrained capacity. Furthermore, a binary convolutional code and the CPM modulator are concatenated using an S-random bit interleaver to lower the error floor. Finally, Laurent representation of the new pulse shape is suggested such that by retaining only the principal pulses at the receiver, complexity of the receiver can be reduced.

Abstract: An apparatus for phase modulation includes a delay locked loop configured to generate from a reference signal a plurality of phase shifted signals, each of the phase shifted signals being locked to the reference signal and having a different phase shift from the other phase shifted signals with respect to the reference signal, and a multiplexer configured to select one of the phase shifted signals.

Abstract: A feedback loop is used to determine phase distortion created in a signal by directly extracting the phase distortion information from a feedback signal using original frequency modulation information.

Abstract: A parametric audio system that permits greater control over the bandwidth of a modulated signal. The system includes a carrier signal generator for generating a carrier signal, at least one audio signal source for generating at least one audio signal, and a modulation component for generating an envelope signal based on the at least one audio signal, modulating the phase of the carrier signal based on a predetermined function to generate a first modulated signal, and multiplying the envelope signal and the first modulated signal to generate a second modulated signal. By selection of the predetermined function, the modulation component can alter the spectrum of the second modulated signal, thereby permitting greater control over the bandwidth of the second modulated signal.

Abstract: A two-point phase modulator and a method of calibrating conversion gain of the same are provided. The two-point phase modulator locks an output frequency signal by charging and pumping charge in a phase-locked loop (PLL) circuit at the beginning of operation, opens a loop of the PLL circuit for a period of time, and applies a step signal, thus calibrating conversion gain of a modulation signal that controls the output frequency signal. Thus, the conversion gain may be accurately calibrated by the calibration operation at one time.

Abstract: A quadrature modulator (QM) may be calibrated by determining total equivalent offsets in the I- and Q-channels, a total equivalent gain imbalance between the I- and Q-channels, and a total equivalent phase skew between the I- and Q-channels. These values may be obtained by taking various scalar measurements of the image to signal ratio (ISR) and carrier to signal ratio (CSR) of the QM, while alternatively altering the system gain imbalance, system phase skew, I-channel offset and Q-channel offset using a respective gain parameter, phase parameter, I-channel offset parameter, and Q-channel parameter. The gain and phase parameters may be defined in terms of the ISR, and the channel offset parameters may be defined in terms of the CSR. The system gain imbalance, system phase skew, and total offset in the channels may then be calculated based on the various ISR and CSR measurements.

Abstract: Clock spreading systems and methods are disclosed. In one embodiment of the invention, a clock spreading system is provided in an integrated transceiver system that comprises a base band control system and a transceiver coupled to the base band control system. The clock spreading system provides a spread clock output signal derived from a clock reference signal for clocking one of the base band control system and the transceiver. The clock spreading system is configured to provide a periodic phase modulated spread clock output signal during receiving of data in a receive mode and a pseudo-random phase modulated spread clock output signal during transmitting of data in a transmit mode.

Abstract: A bi-phase modulator including a driver and a mixer. The driver includes a prescaler having an input for receiving a signal and an output for outputting a baseband signal. The mixer includes a mixer having an input coupled to the output of the prescaler for receiving the baseband signal output by the prescaler. The baseband signal output by the prescaler drives the mixer so as to output a modulated waveform from an output of the mixer.

Abstract: The present invention is a method and an apparatus for optical modulation, for example for use in optical communications links. In one embodiment, an apparatus for optical modulation includes a first silicon layer having one or more trenches formed therein, a dielectric layer lining the first silicon layer, and a second silicon layer disposed on the dielectric layer and filling the trenches.

Abstract: Aspects of a method and system for direct and polar modulation using a two input PLL are presented. Aspects of the system may include generating digital signals Wn and Vn from an input data signal Un and a feedback signal Yn. The generated digital signals Wn and Vn combined may carry the information content of Un while they compensate the non-idealities of the two-input analog phase locked loop (PLL). The digital signal Wn, which may be scaled appropriately in frequency, and the digital signal Vn may be provided as inputs to the PLL. The feedback signal Yn may be a digital signal that may correspond to the analog feedback signal Pt that may be generated by the PLL. Accordingly, the PLL may be adaptively controlled via the digital signals Wn and Vn for properly transmitting the input data signal Un.

Abstract: An apparatus, method and computer program, the apparatus including: a modulator including a first input for receiving a data signal and a second input for receiving an output signal from a phase locked loop wherein the modulator is for modulating the output signal from the phase locked loop using the data signal and providing the modulated signal to an output for connection to an amplifier; and a phase shifter configured to result in a predetermined phase shift to the modulated signal.

Abstract: Polar feedback architecture. A polar modulator, as may be implemented within a transmitter module, of a communication device includes feedback. This feedback involves monitoring of phase information and magnitude/amplitude information of an output signal generated by the polar modulator. The output signal can be a radio frequency (RF) signal such as may be transmitted via a communication channel within a communication system. A baseband processing module processes the monitored phase information and magnitude/amplitude information to perform adjustment of a phase modulator and/or other components within the polar modulator.

Abstract: A vector signal generator with direct RF signal synthesis is disclosed. The vector signal generator comprises an RF signal synthesizer, a switch, and a memory. The RF signal synthesizer is configured for converting baseband IQ signals into a modulated digital RF signal. The RF signal synthesizer is connected to an I input, a Q input, a clock input, a control input, and an output, where the clock input is a clock input of the vector signal generator, the control input is a control input of the vector signal generator, and the output is an RF signal output of the vector signal generator. The switch is configured for selecting a source of IQ signals and is connected to an external I input, an external Q input, a stored signal I input, a stored signal Q input, the control input, an I output, and a Q output. The external I input and external Q input are external IQ inputs to the vector signal generator and the I output and the Q output are connected to the I input and the Q input of the RF signal synthesizer.

Abstract: Clock spreading systems and methods are disclosed. In one embodiment of the invention, a clock spreading system is provided in an integrated transceiver system that comprises a base band control system and a transceiver coupled to the base band control system. The clock spreading system provides a spread clock output signal derived from a clock reference signal for clocking one of the base band control system and the transceiver. The clock spreading system is configured to provide a periodic phase modulated spread clock output signal during receiving of data in a receive mode and a pseudo-random phase modulated spread clock output signal during transmitting of data in a transmit mode.

Abstract: An apparatus and method for generating piecewise linear phase transitions during a phase transition interval of a first signal to control controlling the phase/frequency of a second signal. The initiation point, duration and shaping parameters of the piecewise linear phase transitions are selected to control adjacent channel emissions in the second signal.

Abstract: An apparatus for phase modulation includes a delay locked loop configured to generate from a reference signal a plurality of phase shifted signals, each of the phase shifted signals being locked to the reference signal and having a different phase shift from the other phase shifted signals with respect to the reference signal, and a multiplexer configured to select one of the phase shifted signals.

Abstract: The present invention relates in general to transferring the envelope information of a polar modulated signal to a varying pulsewidth signal, while the phase modulation is direct transferred to the phase modulation of this PWM signal. Accordingly, the resultant signal is a PWM-PPM-signal. Such a signal can efficiently amplified by use of switching amplifying stages. By the present invention four pre-distorted baseband signals are applied basically to 4 linear RF mixers and a two adders, which are, the only needed external RF building blocks to build the modulator according to the invention. That is, the basic idea of the invention resides in the way of modulation of the four baseband signals and the way of combining of the RF modulated signals.

Abstract: Apparatus and methods for providing transmit signals in polar transmitters are described. A modulation signal may be provided from a VCO to low noise and low power signal paths and selectively combined based on a desired output power level. CMOS and CML divider circuits may be used to implement the low noise and low power signal paths respectively, and logic may be provided to select desired signals from the low noise and low power signal stages based on the desired output power level.

Abstract: Polar feedback architecture. A polar modulator, as may be implemented within a transmitter module, of a communication device includes feedback. This feedback involves monitoring of phase information and magnitude/amplitude information of an output signal generated by the polar modulator. The output signal can be a radio frequency (RF) signal such as may be transmitted via a communication channel within a communication system. A baseband processing module processes the monitored phase information and magnitude/amplitude information to perform adjustment of a phase modulator and/or other components within the polar modulator.

Abstract: Provided is a polar modulation apparatus capable of performing power limit with a simple configuration even when controlling a transmission power and increasing the transmission signal output power control range. A polar modulation device (1) includes an amplitude limit unit (6) for limiting an amplitude component of an amplitude signal, a D/A converter (7) for converting an inputted digital signal into an analog signal, a power control unit (8) for performing power control so that the inputted signal is an output signal based on the power control signal, a voltage control circuit (9) for supplying voltage to an amplitude modulator (11) according to the output signal from the power control unit (8), an angle modulator (10) for performing angle modulation according to a phase signal, and an amplitude modulator (11) for performing amplitude modulation on the signal subjected to angle modulation, according to the voltage supplied from the voltage control circuit (9).

Abstract: Provided is a modulation device including a signal selection circuit selecting two carrier signals from a plurality of carrier signals having the same frequency and the same phase difference according to a defined control signal and outputting the selected carrier signals, and a phase interpolator adjusting the phase in smaller units than the phase difference between the plurality of carrier signals according to the control signal and modulating the frequency or the phase of the carrier signal into a baseband signal based on the carrier signals selected by the signal selection circuit to generate a carrier wave signal.

Abstract: An apparatus for providing an angle modulated signal includes a tunable oscillator circuit, a variable time delay circuit, and an optional scaling and delay control apparatus. The tunable oscillator circuit generates an oscillatory signal having a predetermined frequency. The variable time delay circuit operates to delay the oscillatory signal in accordance with time varying changes in an angle control signal, thereby producing the desired angle modulated signal. The scaling and delay control apparatus is configured to scale the angle control signal to account for frequency dependent phase delays of the oscillatory signal through the variable time delay circuit.

Abstract: Enhanced polar modulator for transmitter. Within a phase locked loop (PLL), a two point modulation topology is employed in which phase information passes through a limiter (e.g., a +90° or +re/2) in which the phase information dynamic range is divide by a factor (e.g., by 2) and a maximum frequency deviation is also divided by a factor (e.g., by 2). Then, a double balanced up-converter mixer/modulator is implemented to perform gain adjustment (e.g., magnitude and/or amplitude adjustment) and phase changes of 0° and +180° or 0 and +re (e.g., negative gains values may be employed). Phase adjustment in such an architecture is split and provided to both the PLL and to the mixer/modulator of such a polar modulator within a transmitter module such as may be implemented within a communication device (e.g., which may be a wireless communication device). This architecture that includes a PLL with a double balanced up-converter mixer/modulator suppresses even harmonics.

Abstract: In a driver circuit 10 for outputting a simulated signal simulating an input signal subjected to transmission loss, corresponding to the input signal, the driver circuit 10 comprises: a main driver 18 which receives the input signal and outputs an output signal corresponding to the input signal; a sub driver 20 which receives the input signal and outputs an output signal given by inverting the input signal; a high frequency emphasizing circuit 22 which receives the input signal of the sub driver 20 and outputs an output signal having the high frequency of the input signal of the sub driver 20 emphasized; and an addition unit 24 which outputs the simulated signal given by adding the output signal of the main driver 18 and the output signal of the high frequency emphasizing circuit 22.

Abstract: Linear wideband phase modulation system. Apparatus is provided for linear phase modulation utilizing a phase-locked loop. The apparatus includes a limiting circuit that restricts a range of a modulation signal that is coupled to a voltage controlled oscillator (VCO) associated with the phase-locked loop, and a linearizing circuit that reshapes the modulation signal to improve linearity.

Abstract: The present invention relates to an apparatus and a method for compensating carrier feedthrough in a quadrature modulation system. In order to suppress the carrier feedthrough, and minimize and compensate the carrier feedthrough, differences of baseband differential input DC voltages in an in-phase as well as a quadrature-phase are simultaneously adjusted to 0 or a certain slight voltage difference by a simple analog circuit. Therefore, it is possible to suppress carrier feedthrough using a simple analog type apparatus for compensating carrier feedthrough, and simply achieve an apparatus for carrier feedthrough using a variety of quadrature modulators.

Abstract: It is possible to restrain distortions generated in a mixer. A modulator includes a local signal source that generates an in-phase local signal, a multiplier that multiplies an in-phase baseband signal (I) and the in-phase local signal by each other, a phase inverter that receives the in-phase local signal from the local signal source, and inverts the phase thereof, an anti-phase multiplier that multiplies an anti-phase baseband signal (?I) (signal equivalent to a signal obtained by inverting the phase of the in-phase baseband signal (I)) and an output from the phase inverter (anti-phase local signal) by each other, and an adder that adds an output from the multiplier and an output from the anti-phase multiplier to each other. The addition by the adder of a leak component (carrier leak) which is the in-phase local signal leaked from the multiplier, and the signal which is the output from the phase inverter leaked from the anti-phase multiplier to each other results in zero.

Abstract: A multiband phase shifter (MBPS) consists of at least two band phase shifters (BPSs). Each BPS has characteristic operating bandwidth such that the respective central frequency of the operating bandwidth of any such BPS is different than the other central frequencies of the other operating bandwidth associated with other BPS respectively. The MBPS input signal can be switched to any of the BPS while a switch controller controls the switching.

Abstract: A modulation apparatus 24 comprises a monitoring section 207 operable to monitor information about a control voltage applied to a VCO 201 as control voltage information, during any period, when a low-frequency signal having a frequency within a loop band of a PLL circuit is input at least before an LPF 209, a correction table storing section 206 operable to associate the control voltage information monitored by the monitoring section 207 as information about a control voltage after correction with information about a control voltage before correction, and store the associated information as a correction table, and a correction section 204 operable to correct a control voltage applied to the VCO 201 based on the correction table stored in the correction table storing section.

Abstract: An apparatus for providing an angle modulated signal includes a tunable oscillator circuit, a variable time delay circuit, and an optional scaling and delay control apparatus. The tunable oscillator circuit generates an oscillatory signal having a predetermined frequency. The variable time delay circuit operates to delay the oscillatory signal in accordance with time varying changes in an angle control signal, thereby producing the desired angle modulated signal. The scaling and delay control apparatus is configured to scale the angle control signal to account for frequency dependent phase delays of the oscillatory signal through the variable time delay circuit.

Abstract: A system and method of the present invention forms a hybrid encoded signal. A signal generator generates a coded waveform having a trellis structure, such as a continuous phase modulated signal. A modulator is operative with the signal generator and adds at least one orthogonal or amplitude modulated waveform to a trellis structure of the coded waveform to create a non-constant envelope modulated signal that has at least one of increased bandwidth, improved bit error rate, or an increased number of bits encoded into a single symbol.

Abstract: A communication apparatus has a local oscillator which performs phase modulation based on a phase component of a baseband signal and outputs a phase modulated signal, a controlling circuit which is supplied with an integer portion included in an amplitude component of the baseband signal and generates and outputs a controlling signal based on a size of the integer portion, a subtractor which is supplied with the integer portion and the controlling signal, subtracts a value of the controlling signal from the integer portion, and outputs a result, a MASH (Multi-stAge-noise-Shaping) circuit which is a second-order delta-sigma modulation means supplied with a fractional portion of the amplitude component, an order of the MASH circuit being switchable between a first order and a second order based on the controlling signal, and an amplifier which sets a voltage value based on an output of the MASH circuit and an output of the subtractor, multiplies the voltage value and the phase modulated signal, and outputs a re

Abstract: A polar modulator arrangement has a first and a second node to receive a digital signal with a first and a second component corresponding to a digital amplitude component and a digital phase component. A digital interpolation filter generates an interpolated first component by interpolating and filtering the first component. A polar modulated radio frequency signal is generated by a combination element as a function of the interpolated first component and the second component.

Abstract: A signal generator generates a coded or memory waveform having a trellis structure. A modulator is operative with the signal generator for adding at least one phase pulse to the trellis structure of the coded or memory waveform to create a substantially constant envelope modulated signal that increases the transmitted bits per symbol.

Abstract: A polar-based modulator includes an amplitude signal generator operating at a set gain and a command module that selects an appropriate one parameter lookup table based on an identification of the current network communication system. The command module receives a digital representation of the desired amplitude and using the received digital amplitude and selected parameter lookup table determines control commands used by a scalar to appropriately modulate an amplitude modulated signal output from the amplitude signal generator. Use of the parameter lookup table and command module in the digital realm eliminates the complexities of comparable functionality in the analog realm. Further, operating the amplitude signal generator at a set gain and scaling the output eliminates the complexities associated with generating an appropriately amplified signal within the amplitude signal generator and improves the overall efficiency for generating such an amplitude modulated signal.

Abstract: A drive signal generation unit generates first and second drive signals for driving first and second phase modulators of a DQPSK optical modulator. First and second regeneration circuits regenerate the first and second drive signals with respect to clock signals. The first and second phase modulators are driven by the regenerated first and second drive signals. The amplitude of the first drive signal is adjusted by a first attenuator. The clock signal for the second regeneration circuit is applied after attenuated by a second attenuator. The delay time caused by the first attenuator is the same as the delay time caused by the second attenuator.

Abstract: A multimode-based phase modulating apparatus capable of reducing the degradation of modulation precision and suppressing the unnecessary power consumption. This apparatus has a switch for switching the modulation modes of a PLL circuit between a single-point modulation and a double-point modulation. In a case of a narrow modulation bandwidth, the switch is turned off to cease a second digital baseband signal, thereby causing the PLL circuit to perform the single-point modulation in which only a first digital baseband signal from a frequency division rate generating part is used for the modulation. Contrarily, in a case of a wide modulation bandwidth, the switch is turned on, thereby performing the double-point modulation using both the first digital baseband signal and the second digital baseband signal.

Abstract: Phase shift key modulators (100, 500, 1000, 1400, 1700) are provided in which a multiphase signal source (108, 1402, 1406-1412,1702) is used to generate a plurality of phases of a carrier signal. A selector (110) is used to select one phase or a sequence of phases of the carrier signal to represent each bit pattern that is received from a binary data source (102, 1422). The multiphase signal source preferably comprises a multiphase oscillator that includes a phase locked ring of variable propagation delay inverters (202). Preferably, a phase sequencer (502) is used to select a monotonic sequence of phases to represent each bit pattern. Preferably two phase selectors (110, 1004) are used to simultaneously select two phases of carrier signal, and a phase interpolator (1106) is used to generate a sequence of phases from the two phases selected by the two phase selectors (110, 1004).

Abstract: A high speed passband phase modulation apparatus and method are provided. In the phase modulation apparatus, an RF phase shifter modulates a phase of a local signal that is generated in a VCO according to a digital input. The RF phase shifter is controlled by a phase-controlled loop so that a baseband phase shifter is phased locked to a modulation reference signal from the local signal and a reference clock signal according to the digital input. The phase-controlled loop phase-locks using the modulation reference signal so that the phase-modulated signal generated in the RF phase shifter has a phase value according to the digital input.

Abstract: There provides a two-point modulation phase modulation apparatus capable of obtaining an RF phase modulation signal of superior modulation precision with low power consumption and a simple configuration even in the event of inputting a wide band baseband modulation signal. A differentiator (21) of the opposite characteristics to the attenuation characteristics of anti-alias filter (22) is provided at the front stage of a D/A converter (6). As a result, it is possible to sufficiently suppress an alias signal without raising the sampling frequency of the D/A converter (6) (i.e. low power consumption) using an anti-alias filter (22) of a simple configuration (i.e. low cost) with a low order for a narrower bandwidth than a PLL modulation frequency bandwidth, and it is possible to obtain an RF phase modulation signal where the entire frequency band of input digital baseband modulation signal (S1) is reflected in a superior manner.

Abstract: Aspects of a method and system for direct and polar modulation using a two input PLL are presented. Aspects of the system may include generating digital signals Wn and Vn from an input data signal Un and a feedback signal Yn. The generated digital signals Wn and Vn combined may carry the information content of Un while they compensate the non-idealities of the two-input analog phase locked loop (PLL). The digital signal Wn, which may be scaled appropriately in frequency, and the digital signal Vn may be provided as inputs to the PLL. The feedback signal Yn may be a digital signal that may correspond to the analog feedback signal Pt that may be generated by the PLL. Accordingly, the PLL may be adaptively controlled via the digital signals Wn and Vn for properly transmitting the input data signal Un.

Abstract: A jitter generating device for generating a jitter on a carrier signal includes: a carrier signal generator for generating the carrier signal; a modulation signal generator for generating a modulation signal corresponding to the jitter; an orthogonal modulator for modulating a phase of the carrier signal generated by the carrier signal generator using the modulation signal generated by the modulation signal generator as one of modulation input signals; a DC power supply for applying a DC voltage serving as the other modulation input signal to the orthogonal modulator; and a limiter amplifier for setting an amplitude of an output signal of the orthogonal modulator to be constant.

Abstract: A modulator arrangement includes a power amplifier which receives a carrier signal and has a current control input and a voltage supply input. The modulator arrangement further includes a supply voltage modulator having an output coupled to the voltage supply input and an input coupled to the data input and a bias current modulator with an output coupled to the current control input and an input coupled to the data input. A control unit is provided which has a power control output coupled to the supply voltage modulator and to the bias current modulator to control the supply voltage modulator and the bias current modulator depending on a power control signal.

Abstract: A polar modulator contains a phase locked loop which is designed to emit a radio-frequency signal at one frequency to one output, with the frequency being derived from the reference signal and from a phase modulation signal at a control input of the phase locked loop. The modulator additionally has a second signal input for supplying an amplitude modulation signal. The second signal input is connected to a control input of a pulse width modulator, one of whose signal inputs is coupled to the output of the phase locked loop. The pulse width modulator is designed to vary the duty ratio of a signal which is applied to the signal input, with this variation being adjustable via a regulation signal at the control input. A filter can be connected downstream from the output of the pulse width modulator and suppresses higher harmonic components in a signal which can be tapped off at the output of the pulse width modulator.

Abstract: A signal modulation device comprises a delta-sigma modulator disposed for transforming an amplitude-modulation signal in baseband into a pulse signal. It also comprises a phase modulator receiving, at its input, analogue phase-modulation signals in baseband. The pulse signal is mixed with carrier signals upstream of the phase modulator. The modulation device is designed to form an input stage of a transmitter.

Abstract: The invention concerns a device for producing a phase and amplitude modulated signal (G) suitable for radio transmission via an antenna (30), based on the EER technique and means (20) for temporal clamping of a phase controlling signal (D) and an amplitude controlling signal (F) so that the phase modulating component is synchronized with the amplitude modulating component in the output signal (G).

Abstract: A method for reducing out-of-band emission in an AM transmitter for digital transmission includes generating, from a digital modulation signal, an amplitude signal and a phase-modulated radio frequency signal configured to control the AM transmitter. A digital modulation process is used in which a hole is formed around a 0/0 point so that a zero crossing is avoided by a substantial margin in a vector diagram representation. Thereby a respective bandwidth of the amplitude signal and the phase-modulated radio frequency signal is limited so that the out-of-band emission decreases as a function of a shoulder distance achievable by the AM transmitter at a rate where a spectrum mask is not exceeded.

Abstract: An apparatus and method for high speed phase modulation of optical beam with reduced optical loss. In one embodiment, an apparatus includes a first region of an optical waveguide disposed in semiconductor material. The first region has a first conductivity type. The apparatus also includes a second region of the optical waveguide disposed in the semiconductor material. The second region has a second conductivity type opposite to the first conductivity type. A first contact is included in the apparatus and is coupled to the optical waveguide at a first location in the first region outside an optical path of an optical beam to be directed through the optical waveguide. The apparatus also includes a first higher doped region included in the first region and coupled to the first contact at the first location to improve an electrical coupling between the first contact and the optical waveguide. The first higher doped region has a higher doping concentration than a doping concentration within the optical path.

Abstract: Polar modulators include a phase splitter, a controller, variable current sources, transistor circuits, and a combiner. The phase splitter splits a RF carrier signal into quadrature component signals that are 90 degrees out of phase with each other. The controller generates modulation control signals based on information that is to be transmitted. The variable current sources each generate a variable amplitude current signal based on a different one of the modulation control signals. Each of the transistor circuits amplify a different one of the quadrature component signals with a variable amplification based on the variable amplitude current signal from a different one of the variable current sources to generate an amplitude adjusted quadrature component signal. The combiner combines the amplitude adjusted quadrature component signals from each of the transistor circuits to generate a phase-modulated RF carrier output signal.