Abstract: Apparatus and methods for multi-mode power amplifiers are provided herein. In certain configurations, a wireless device includes a multi-mode power amplifier including a plurality of amplification paths electrically connected in parallel with one another. The plurality of amplification paths includes a first amplification path including an input stage of a first stage type and an output stage of a second stage type, and a second amplification path including an output stage of the second stage type. The first stage type provides non-inverting gain and the second stage type provides inverting gain. The wireless device further includes a transceiver that provides a radio frequency signal to the multi-mode power amplifier, and that operates the multi-mode power amplifier in a selected power mode chosen from a plurality of power modes based on selectively activating one or more of the plurality of amplification paths.

Abstract: Switchable feedback circuit for radio-frequency (RF) power amplifiers. In some embodiments, an RF power amplifier (PA) circuit can include a transistor having a base, a collector, and an emitter. The transistor can be configured to amplify an RF signal. The RF PA circuit can further include a switchable feedback circuit implemented between the collector and the base. The switchable feedback circuit can be configured to provide a plurality of resistance values between the collector and the base. Such a PA circuit can be implemented in products such as a die, a module, and a wireless device.

Abstract: Aspects of this disclosure relate to efficient power amplifiers, such as class-F power amplifiers. A power amplifier transistor can provide an amplified RF signal. A termination can be coupled to an output of the power amplifier transistor and configured to provide a short circuit at a second harmonic. In some instances, the termination circuit can provide an open circuit at a third harmonic. A resonant circuit can be coupled to the output terminal of the power amplifier transistor and configured to provide an open circuit at the third harmonic. In certain embodiments, an input termination circuit coupled to an input terminal of the power amplifier transistor can provide a short circuit at the second harmonic. The power amplifiers of this disclosure can be implemented, for example, in envelope tracking applications.

Abstract: Aspects of this disclosure relate to efficient power amplifiers, such as class-F power amplifiers. A power amplifier transistor can provide an amplified RF signal. A termination can be coupled to an output of the power amplifier transistor and configured to provide a short circuit at a second harmonic. In some instances, the termination circuit can provide an open circuit at a third harmonic. A resonant circuit can be coupled to the output terminal of the power amplifier transistor and configured to provide an open circuit at the third harmonic. In certain embodiments, an input termination circuit coupled to an input terminal of the power amplifier transistor can provide a short circuit at the second harmonic. The power amplifiers of this disclosure can be implemented, for example, in envelope tracking applications.

Abstract: A complex fuel cell stack with hydrogen storage unit is introduced. Through the new configuration of the PEM fuel cell stack, no cooling system and cooling fluid is needed for the fuel cell stack, since hydrogen storage vessel can act as a heat sink to protect the expensive catalyst layer of the MEA of the fuel cell away from over-heated and damaged. In addition, the waste heat generated from the operation of the fuel cells can aid in release of hydrogen from hydrogen storage alloys inside the hydrogen storage vessel.

Abstract: Aspects of this disclosure relate to a mode linearization switch circuit that can adjust an effective impedance provided to an output of an amplifier. In an embodiment, an apparatus includes an amplifier configured to amplify a radio frequency (RF) signal and a mode linearization switch circuit electrically coupled to an output of the amplifier. The mode linearization switch circuit can include a capacitor, a switch in series with the capacitor, and a series LC circuit in parallel with the switch.

Abstract: Aspects of this disclosure relate to efficient power amplifiers, such as class-F power amplifiers. A power amplifier transistor can provide an amplified RF signal. A termination can be coupled to an output of the power amplifier transistor and configured to provide a short circuit at a second harmonic. In some instances, the termination circuit can provide an open circuit at a third harmonic. A resonant circuit can be coupled to the output terminal of the power amplifier transistor and configured to provide an open circuit at the third harmonic. In certain embodiments, an input termination circuit coupled to an input terminal of the power amplifier transistor can provide a short circuit at the second harmonic. The power amplifiers of this disclosure can be implemented, for example, in envelope tracking applications.

Abstract: Switchable base feed circuit for radio-frequency (RF) power amplifiers. In some embodiments, an RF power amplifier (PA) circuit can include a transistor having a base, a collector, and an emitter, with the transistor being configured to amplify an RF signal. The PA circuit can further include a bias circuit configured to provide a base bias signal to the base of the transistor. The PA circuit can further include a switchable base feed circuit implemented between the bias circuit and the base of the transistor. The switchable base feed circuit can be configured to provide a plurality of different resistance values for the base bias signal between the bias circuit and the base of the transistor. Such a PA circuit can be implemented in products such as a die, a module, and a wireless device.

Abstract: Switchable feedback circuit for radio-frequency (RF) power amplifiers. In some embodiments, an RF power amplifier (PA) circuit can include a transistor having a base, a collector, and an emitter. The transistor can be configured to amplify an RF signal. The RF PA circuit can further include a switchable feedback circuit implemented between the collector and the base. The switchable feedback circuit can be configured to provide a plurality of resistance values between the collector and the base. Such a PA circuit can be implemented in products such as a die, a module, and a wireless device.

Abstract: An extended film and a manufacturing method thereof are provided. The extended film includes a poly(lactic acid) and a block copolymer, wherein the block polymer includes a first block, a second block and a third block that connected with each other by chemical bonds. The extended film is formed by steps of mixing poly(lactic acid) and the block copolymer to form a mixture, compressing the mixture to form a board body and extending the board body to form an extended film, thereby forming an extended film having properties of high thermal-resistance and high transparency, the film thus obtained is applicable for packaging use.

Abstract: A method for preparing a scandium-doped hafnium oxide film, includes preparing a hafnium target having scandium granules distributed on a peripheral surface thereof; and proceeding a sputtering process to form a scandium-doped hafnium oxide film on a substrate, wherein the scandium doping of the scandium-doped hafnium oxide film is in the range of 3-13%. Such scandium-doped hafnium oxide film is able to be used as an oxide layer in semiconductor element which effectively suppresses the current leakage and reduces the dimension of the semiconductor element.

Abstract: This invention, which relates to retrieving an object from a video or a photo where the object matches a hand-drawn sketch, discloses a method for automatically estimating a perceptual bias level with respect to a feature of the sketch. The method allows estimation based on the sketch alone without involving an extra database. In one embodiment, the method comprises using an expectation-maximization tensor voting (EMTV) method to analyze a statistical distribution of the feature. The statistical distribution is analyzed by forming an objective function having the statistical distribution's information parameterized by the perceptual bias level, and then maximizing the objective function according to a set of iterative update rules. In another embodiment, the method for automatically estimating a perceptual bias level is incorporated into a method for retrieving one or more objects from an image or video database where the one or more objects match a hand-drawn sketch.

Abstract: Apparatus and methods for reducing capacitive loading of a power amplifier supply control module are disclosed. In one embodiment, a method of power supply control in a power amplifier system includes controlling a voltage level of a supply voltage using a supply control module, amplifying a first radio frequency (RF) signal using a first power amplifier module, amplifying a second RF signal using a second power amplifier module, delivering the supply voltage to a first supply input of the first power amplifier module through a first resonant circuit, and delivering the supply voltage to a second supply input of the second power amplifier module through a second resonant circuit. The first resonant circuit includes a first inductor and a first capacitor electrically connected in parallel, and the second resonant circuit includes a second inductor and a second capacitor electrically connected in parallel.

Abstract: Disclosed is a method for manufacturing a film. 50 wt % to 85 wt % of a first polyester and 50 wt % to 15 wt % of a second polyester are dried and mixed to form a mixture. The first polyester is polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or combinations thereof. The second polyester is copolymerized of 1 part by mole of terephthalic acid, m parts by mole of 1,4-cyclohexanedimethanol (1,4-CHDM), n parts by mole of 1,3-cyclohexanedimethanol (1,3-CHDM), and o parts by mole of ethylene glycol (EG). m+n+o=1, 0?o?0.4, 0.6?m+n?1, and 0.06?n/m?1.31. The mixture is melted and blended to form a polyester composition, which is extruded to form a sheet. The sheet is then biaxially stretched to obtain a film. The biaxially stretched film is then treated with a thermal setting.

Abstract: An enterosoluble and intestinal-enzyme-biodegradable material is provided. The enterosoluble and intestinal-enzyme-biodegradable material includes a modified amylopectin, wherein at least one of hydrogen atoms is replaced by —CO—(CH2)n—COOH (n is 2-4) and the modified amylopectin has an acid value of 35-180 mg KOH/g. The disclosure also provides a method for preparing an enterosoluble and intestinal-enzyme-biodegradable material.

Abstract: A method for preparing scandium-doped hafnium oxide film includes preparing a hafnium target having scandium granules distributed on a peripheral surface thereof; and proceeding a sputtering process to form a scandium-doped hafnium oxide film on a substrate, wherein the scandium doping of the scandium-doped hafnium oxide film is in the range of 3-13%. Such scandium-doped hafnium oxide film is able to be used as an oxide layer in semiconductor element which effectively suppresses the current leakage and reduces the dimension of the semiconductor element.

Abstract: Apparatus and methods for reducing capacitive loading of a power amplifier supply control module are disclosed. In one embodiment, a method of power supply control in a power amplifier system includes controlling a voltage level of a supply voltage using a supply control module, amplifying a first radio frequency (RF) signal using a first power amplifier module, amplifying a second RF signal using a second power amplifier module, delivering the supply voltage to a first supply input of the first power amplifier module through a first resonant circuit, and delivering the supply voltage to a second supply input of the second power amplifier module through a second resonant circuit. The first resonant circuit includes a first inductor and a first capacitor electrically connected in parallel, and the second resonant circuit includes a second inductor and a second capacitor electrically connected in parallel.

Abstract: A polyester film is described, including a first polyester and a second polyester. The weight ratio of the first polyester to the second polyester ranges from 1:1 to 1:3. The glass transition temperature of the first polyester is higher than 140° C. and that of the second polyester is lower than 140° C.

Abstract: An amplitude modulation circuit in a polar transmitter includes a digital-to-analog converter (DAC), a filter, a gm stage, and a calibration module. The DAC is arranged to be coupled to an amplitude modulation signal input in a normal mode. The filter is coupled to the DAC, and the gm stage is coupled to the filter. The calibration module has an input coupled to the gm stage, and an output coupled to a node on a path between the DAC and the gm stage. A method for calibrating an amplitude offset in the polar transmitter includes: generating an amplitude offset calibration signal according to an amplitude modulation signal generated from the gm stage; and transmitting the amplitude offset calibration signal via the output of the calibration module to a node on a path between the DAC and the gm stage so as to calibrate the amplitude offset.