摘要:
A power amplifier includes a carrier amplifier path and a peaking amplifier path. The carrier amplifier path includes a carrier amplifier (208), and an impedance transforming network (214). The peaking amplifier path includes a peaking amplifier (210), an impedance transforming network (216), and a phase delay quarter wave element (226). The arrangement forms an inverted Doherty combiner where as the nominal impedance at a summing node (230) increases with increased conduction from the peaking amplifier, the load impedance at the output of the carrier amplifier decreases so as to maintain the carrier amplifier at a saturation point as the input signal (232) increases, and results in a reduction of the number of phase delay elements needed over a conventional Doherty approach. In a preferred embodiment the carrier and peaking amplifiers consist of cascaded stages, and are disposed on a common integrated circuit die (304). The impedance transforming networks and phase delay element are disposed on a common substrate (306), as is an input splitter network (308).
摘要:
An amplifier apparatus for a multimode mobile communication device includes a carrier amplifier (114) and a peaking amplifier (116). The peaking amplifier has an adjustable bias level and is adjusted by a regulator to a predetermined level, depending on which mode of communication is selected. The bias level on the peaking amplifier is held constant so long as the mode of communication is the same. By adjusting the bias point of the peaking amplifier in conjunction with the selection of the mode of communication, the efficiency and the linearity of modulation can be optimized for the particular mode of communication.
摘要:
A high efficiency power amplifier 600 consists of a non-linear radio frequency (RF) Doherty power amplifier (67) and a linearization circuit, such as, for example, a Cartesian Feedback circuit (33), an RF feedback circuit (38), an IF feedback circuit (48), or a feedforward circuit (55). The Doherty amplification stage (67) may be implemented with a BJTs, FETs, HBTs, H-FETs, PHEMTs, or any other type power transistor technology or device.
摘要:
A method and apparatus is provided for a transmitter (200) with a stable, linear response. The transmitter (200) includes an amplification stage (242), and a negative feedback correction loop (244) with a feedback signal (252). A reference signal (251) is combined with the feedback signal (252) to produce an error signal (253) for coupling to the amplification stage (242). Transmitter parameters are varied when a difference between the reference signal (251) and the error signal (253) exceeds a particular threshold.
摘要:
An amplifier structure (200) includes a main amplifier loop (203) for efficiently amplifying an input signal at a power amplifier (228) coupled to a load susceptible to impedance variations. The amplifier structure (200) includes a DC correction circuit (214) for detecting and correcting misadjustments in the amplifier (200) in order to eliminate DC offset associated therewith.
摘要:
A linear transmitter (100), which utilizes closed loop feedback to maintain its linearity, employs a method for reducing off-channel interference produced by the linear transmitter (100). A dynamically alterable parameter source (DAPS, 126) is provided to the linear transmitter (100). The DAPS (126) is then used to adjust at least one loop parameter of the closed loop feedback such that off-channel interference is reduced.
摘要:
An H-bridge circuit formed from two sub-circuits coupled to each other by a load network across a respective load node of each of the sub-circuits. Each sub-circuit of the two sub-circuits comprises a depletion mode upper transistor with a second electrode coupled to a first electrode of a lower transistor. The load node of the sub-circuit is disposed between the second electrode of the upper transistor and the first electrode of a lower transistor. There is a first voltage supply node coupled to a first electrode of the upper transistor and a second voltage supply node is coupled to a second electrode of the lower transistor. An upper driver transistor selectively couples a gate electrode of the upper transistor to an upper drive voltage node, the upper driver transistor having a control electrode coupled to an upper switched voltage supply circuit. There is also a lower switched voltage supply circuit coupled to a gate electrode of the lower transistor and a voltage dependent non-linear resistor is coupled across the gate electrode and second electrode of the upper transistor. In use, when the lower transistor and upper driver transistor are in a non-conductive state a potential difference across the voltage dependent non-linear resistor is sufficiently small enough to control the upper transistor into a conductive state. Conversely, when the lower transistor and upper driver transistor are in a conductive state the potential difference across the voltage dependent non-linear resistor provides a negative bias to the gate electrode of the upper transistor that has a negative potential sufficient to control the upper transistor into a non-conductive state.
摘要:
In a radio transmitter (100) that includes a power amplifier (104) and an antenna (106), a method for enhancing an operating characteristic of the radio transmitter (100) can be accomplished in the following manner. The power amplifier (104) provides a signal (113) to a variable matching network (111), wherein the signal (113) comprises energy to be radiated by the antenna (106). The variable matching network (111) couples the signal (113) to a sampler (112) that is operably coupled to an output of the variable matching network (111 ) and the antenna (106). The sampler (112) samples a forward component (114) and a reflected component (115) of the signal (113). The radio transmitter (100) processes the sampled forward and reflected components (116, 118) to produce a feedback control signal (120). The feedback control signal (120) is used to adjust the variable matching network (111 ), such that an operating characteristic of the radio transmitter (100) is enhanced.
摘要:
A broadband RF transformer design is described that facilitates the construction of a broadband impedance transformer in a compact, planar format, while retaining ease of assembly and manufacture. Broadband operation is achieved through the use of a slotted low-impedance winding structure, common-manufacture ferrite elements, and the optional placement of reactive elements between winding turns. By virtue of construction, thermal performance is enhanced, allowing operation at power levels not previously possible. The invention accommodates functional tuning via laser or abrading techniques. Also, the winding configuration eliminates the need to access the center of a spiral for the purposes of establishing a ground connection.
摘要:
A method and apparatus for direct conversion of digital data to high power RF signals, known as DDRF. The method and apparatus receive a digital signal, create a digital modulated signal therefrom, and amplify the modulated signal with an H-bridge Power Amplifier for transmission. DDRF uses a multi-level H-bridge amplification circuit to establish a more power efficient digital transmitter.