2820results about "Amplifiers with semiconductor devices only" patented technology

Provided is a transmission circuit which allows smooth switching of the operation mode when switching the operation mode of the transmission circuit. A power amplifier 14 includes: a first input terminal to which a direct-current voltage or a voltage in accordance with an amplitude signal M is supplied; a second input terminal to which an output signal from a first variable gain amplifier 171 or an output signal from a second variable gain amplifier 172 is inputted; and a third input terminal to which an output signal from a first bias circuit 15 or an output signal from a second bias circuit 16 is inputted. A control section 11 switches the operation mode of the transmission circuit so that at least one of the first input terminal, the second input terminal, and the third input terminal of the power amplifier is prevented from being in a no input state.

A device for bi-directional amplification of data signals over power lines is disclosed. In one embodiment, the device includes a bandpass filter, a frequency converter and an amplifier. The bandpass filter filters out undesired frequencies and the frequency converter converts the frequency band of the data signals to a different frequency band. The output of the filter is provided to the amplifier for amplifying the frequency converted data signals for transmission over power line.

An energy-efficient consumer device audio power output stage provides improved battery life and reduced power dissipation. A power supply having a selectable operating mode supplies the power supply rails to the power amplified output stage. The operating mode is controlled in conformity with the audio signal level, which may be determined from a volume control setting of the device and / or from a signal level detector that determines the amplitude of the signal being amplified. The power supply may be a charge pump in which the operating mode uses a capacitive divider to provide for selection of a power supply output voltage that is a rational fraction of the power supply output voltage in a full-voltage operating mode.

An embodiment of the present invention provides an apparatus, comprising an input port and a dynamic impedance matching network capable of determining a mismatch at the input port and dynamically changing the RF match by using at least one matching element that includes at least one voltage tunable dielectric capacitor. The matching network may be a “Pi”, a “T”, or “ladder” type network and the apparatus may further comprise at least one directional coupler capable of signal collection by sampling a portion of an incident signal, a reflected signal or both. In an embodiment of the present invention, the apparatus may also include a control and power control & logic unit (PC LU) to convert input analog signals into digital signals and sensing VSWR phase and magnitude and processing the digital signals using an algorithm to give it a voltage value and wherein the voltage values may be compared to values coming from the coupler and once compared and matched, the values may be passed to a Hi Voltage Application Specific Integrated Circuit (HV ASIC) to transfer and distribute compensatory voltages to the matching network elements.

A method for providing power management in a radio frequency power amplifier using adaptive envelope tracking is provided that includes receiving an input voltage. A power control signal is received. A feedback signal is received. An amplifier input signal is received. From the input voltage, a regulated power supply signal is generated based on the power control signal, the feedback signal, and the amplifier input signal.

High-efficiency envelope tracking (ET) methods and apparatus for dynamically controlling power supplied to radio frequency power amplifiers (RFPAs). An exemplary ET circuit includes a switch-mode converter coupled in parallel with a split-path linear regulator. The switch-mode converter is configured to generally track an input envelope signal Venv and supply the current needs of a load (e.g., an RFPA). The split-path linear regulator compensates for inaccurate envelope tracking by sourcing or sinking current to the load via a main current path. A current sense path connected in parallel with the main current path includes a current sense resistor used by a hysteresis comparator to control the switching of the switch-mode converter. The split-path linear regulator is configured so that current flowing in the current sense path is a lower, scaled version of the current flowing in the main current path.

Various methods and circuital arrangements for biasing one or more gates of stacked transistors of an amplifier are presented, where the amplifier can be an envelope tracking amplifier. Circuital arrangements to generate reference gate-to-source voltages for biasing of the gates of the transistors of the stack are also presented. Particular biasing for a case of an input transistor of the stack is also presented.

Expansion of the bandwidth of a wideband CMOS data amplifier is accomplished using various combinations of shunt peaking, series peaking, and miller capacitance cancellation. These various combinations are employed in any of the amplifier input stage, in intermediate stages, or in the last stage.

Systems and methods are provided for determining and providing an appropriate variable voltage supply to a power amplifier. A power amplifier is operative to amplify an input signal. A digital buffer stores a copy of the input signal representing a predetermined interval of time. An envelope profiler analyzes the buffered interval of the input signal and determines an appropriate supply signal profile for the power amplifier over the predetermined time interval. A supply control provides a supply signal according to the determined profile.

Various envelope tracking amplifiers are presented that can be switched between an ET (envelope tracking) mode and a non-ET mode. Switches and / or tunable components are utilized in constructing the envelope tracking amplifiers that can be switched between the ET mode and the non-ET mode.

An embodiment of the present invention provides an amplifier system, comprising at least one variable impedance matching network, the output of which provides the input to at least one amplifier stage or provides an output of the power amplifier itself, and a bias network associated with the at least one amplifier stage. The amplifier system may further comprise a controller enabling impedance control to the at least one variable impedance matching network and a supply voltage provided to the at least one variable impedance network and / or the at least one amplifier stage and wherein the at least one variable impedance network and the at least one amplifier stage may be a plurality of impedance networks connected to a plurality of amplifier stages. The at least one variable impedance network may include at least one variable capacitor and the at least one variable capacitor may be a voltage tunable dielectric capacitor which may include Parascan® voltage tunable dielectric material.

A supply voltage controlled power amplifier that comprises a power amplifier, a closed power control feedback loop configured to generate a power control signal, and a dual voltage regulator coupled to the power control feedback loop, the dual voltage regulator comprising a first regulator stage and a second regulator stage, wherein the closed power control loop minimizes noise generated by the first regulator stage.

An RF switch to controllably withstand an applied RF voltage Vsw, or a method of fabricating such a switch, which includes a string of series-connected constituent FETs with a node of the string between each pair of adjacent FETs. The method includes controlling capacitances between different nodes of the string to effectively tune the string capacitively, which will reduce the variance in the RF switch voltage distributed across each constituent FET, thereby enhancing switch breakdown voltage. Capacitances are controlled, for example, by disposing capacitive features between nodes of the string, and / or by varying design parameters of different constituent FETs. For each node, a sum of products of each significant capacitor by a proportion of Vsw appearing across it may be controlled to approximately zero.

A power amplifier matching circuit is provided. The matching circuit includes a ferro-electric tunable component. A control signal is applied to the tunable component, changing the component's impedance. This changes the impedance of the matching circuit.

The challenge of the present invention is to suppress a variation in brightness of an image and make a reference value of a black level converge at an appropriate value in a short time. Acondition judgment circuit judges whether or not a frame of an amount of change in gains of a variable gain amplifier being equal to or greater than a threshold continues for a predefined frames or more. If a frame of an amount of change in the gains being equal to or greater than the threshold continues for the predefined frames, a black level value of the current frame is set for new black level reference. If not continues for the predetermined number, the previous black level reference value is retained in lieu of correcting the black level.

A method and an arrangement for detecting impedance mismatch between an output of a radio frequency amplifier (200, 901, 911, 921, 1101) which has an amplifying component (201, 301, Q46, 701, 801) and an input of a load (203, 302) coupled to the output of the radio frequency amplifier having: first monitoring means (401) to monitor a measurable electric effect (311) at a side of the amplifying component (201, 301, Q46, 701, 801) other than the load (203, 302) and to produce a first measurement signal (411). Second monitoring means (402) monitor a measurable electric effect (312) between the amplifying component (201, 301, Q46, 701, 801) and the load (203, 302) and produce a second measurement signal (412). Decision-making means (204, 902, 912, 923, 1102) receive said first (411) and second (412) measurement signals and decide, whether said first and second measurement signals together indicate impedance mismatch.

A scalable periphery tunable matching power amplifier is presented. Varying power levels can be accommodated by selectively activating or deactivating unit cells of which the scalable periphery tunable matching power amplifier is comprised. Tunable matching allows individual unit cells to see a constant output impedance, reducing need for transforming a low impedance up to a system impedance and attendant power loss. The scalable periphery tunable matching power amplifier can also be tuned for different operating conditions such as different frequencies of operation or different modes.

Various embodiments of methods and apparatus for an amplifier with wide output voltage swing are disclosed. The amplifier may include multiple output stages, each associated with a distinct supply voltage. Each output stage may contribute current to the output of the amplifier over a range of amplifier output voltages and these ranges may overlap. Each output stage may contribute current until the amplifier output voltage reaches the supply voltage associated with that output stage. The amplifier output may be as great as the largest supply voltage minus a drop equal to Rdson for an output transistor multiplied by the output current. In a CMOS implementation, this voltage drop may be approximately 0.15V. When the amplifier output voltage is close to the supply voltage associated with an output stage, both that output stage and the output stage associated with the next highest supply voltage may contribute to the amplifier output.

Optimization methods via various circuital arrangements for amplifier with variable supply power are presented. In one embodiment, a switch can be controlled to include or exclude a feedback network in a feedback path to the amplifier to adjust a response of the amplifier dependent on a region of operation of the amplifier arrangement (e.g. linear region or compression region).

A system is provided for substantially reducing variation in AM to PM distortion of a power amplifier caused by variations in RF drive power and temperature. The system includes power control circuitry and power amplifier circuitry. The power amplifier circuitry includes an input amplifier stage and at least one additional amplifier stage coupled in series with the input amplifier stage. The power control circuitry provides a first supply voltage to the input amplifier stage based on a control signal such that the first supply voltage has a predetermined DC offset with respect to the control signal. The first supply voltage is provided such that the predetermined DC offset substantially reduces variations in the AM to PM distortion of the power amplifier due to variations in radio frequency (RF) drive power.

An audio switching power amplifier having an output pulse voltage selected in conformity with an indication of the output signal amplitude provides lower electromagnetic interference (EMI) in class-D amplifier implementations, in particular, in inductor-less designs. The output pulse voltage may be selected by providing multiple switching circuits, such as half or fully bridge switches, with each switching circuit connected to a different power supply. One of the switching circuits is activated by the switching controller, while the others are disabled, providing selection of the output pulse voltage. Selection of a lower pulse voltage, when the maximum voltage is not required, reduces the generated EMI. The switching frequency of the class-D amplifier may also be controlled in conformity with the output signal amplitude, so that at higher output levels a lower switching rate is selected, reducing the generated EMI.

The present invention, generally speaking, provides methods and apparatus for producing an amplitude modulated communications signal, in which a constant-envelope carrier signal is modified in response to a power control signal to produce a modified constant-envelope carrier signal. The modified constant-envelope carrier signal is amplified in response to an amplitude modulation signal to produce a communications signal having amplitude modulation and having an average output power proportional to a signal level of the modified constant-envelope carrier signal. This manner of operation allows wide dynamic range of average output power to be achieved. Because amplitude modulation is applied after amplitude varying circuitry used to produce the modified constant-envelope carrier signal, the amplitude modulation is unaffected by possible non-linearities of such circuitry. In accordance with another aspect of the invention, operation in the foregoing manner at comparatively low average output power levels is combined with switch mode operation at comparatively high average output power levels, enabling high overall efficiency to be achieved. Hence, the disclosed modulator and amplifier combination, in addition to supporting very low power signals, also supports high power signals.

A transmitting arrangement includes a matching circuit, a reference circuit and a comparator. The output of the matching circuit can be coupled to an antenna and comprises an adjustable impedance. The reference circuit is connected to an input of the matching circuit and comprises a reference impedance. Inputs of the comparator are coupled to the matching circuit and the reference circuit and its output is coupled to the adjustable impedance via a control input of the matching circuit.

A tunable constant GM circuit allows to compensate for temperature and process variations with high precision by correspondingly adjusting a resistance value and / or the ratio of transistor widths. Thus, in switched capacitor circuits the frequency behaviour, such as the settling time, may be controlled by providing a compensated bias to the transconductance amplifiers typically used in these circuits.

An RF power amplifier system comprises an amplitude control loop and a phase control loop. The amplitude control loop adjusts the supply voltage to the power amplifier based upon the amplitude correction signal indicating the amplitude difference between the amplitude of the input signal and an attenuated amplitude of the output signal. The phase control loop adjusts the phase of the input signal based upon a phase error signal indicating a phase difference between phases of the input signal and the output signal. The phase control loop may comprise one or more variable phase delays introducing a relative phase delay to allow the phase differences between the input and output signals of the PA circuit to be within a range compatible with a phase comparator generating the phase error signal, and a low frequency blocking module that removes the larger extent, lower frequency components of the phase error signal.