Techniques for monitoring a distortion signal of a power amplifier circuit, where the output of a distortion monitoring circuit includes little or no fundamental signal and closely represents the actual distortion of the amplifier circuit of a wired communications system. The power amplifier circuit can generate a distortion feedback signal that does not affect the power amplifier's output power capability, e.g., no inherent loss in the fundamental output of the amplifier. That is, using a distortion monitor circuit, the power amplifier circuit can resolve a distortion feedback signal from the intended output signal of the output power amplifier circuit.

In accordance with an embodiment, a circuit includes: a replica input transistor, a first replica cascode transistor, an active current source, and an active cascode biasing circuit. The active current source is configured to set a current flowing through the first replica cascode transistor and the replica input transistor to a predetermined value by adjusting a voltage of a control node of the replica input transistor; and an active cascode biasing circuit including a first output coupled to the control node of the first replica cascode transistor, and the active cascode biasing circuit configured to set a drain voltage of the replica input transistor to a predetermined voltage by adjusting a voltage of the control node of the first replica cascode transistor.

Bias circuits and methods for silicon-based amplifier architectures that are tolerant of supply and bias voltage variations, bias current variations, and transistor stack height, and compensate for poor output resistance characteristics. Embodiments include power amplifiers and low-noise amplifiers that utilize a cascode reference circuit to bias the final stages of a cascode amplifier under the control of a closed loop bias control circuit. The closed loop bias control circuit ensures that the current in the cascode reference circuit is approximately equal to a selected multiple of a known current value by adjusting the gate bias voltage to the final stage of the cascode amplifier. The final current through the cascode amplifier is a multiple of the current in the cascode reference circuit, based on a device scaling factor representing the relative sizes of the transistor devices in the cascode amplifier and in the cascode reference circuit.

A low-noise amplifier device includes an inductive input element, an amplifier circuit, an inductive output element and an inductive degeneration element. The amplifier device is formed in and on a semiconductor substrate. The semiconductor substrate supports metallization levels of a back end of line structure. The metal lines of the inductive input element, inductive output element and inductive degeneration element are formed within one or more of the metallization levels. The inductive input element has a spiral shape and the an amplifier circuit, an inductive output element and an inductive degeneration element are located within the spiral shape.

An embodiment of the present invention provides a RF power amplifier. The RF power amplifier comprises an RF input distribution network, multiple amplifiers and a signal combining network. The RF input distribution network is configured to divide an input RF signal into a main input signal and an auxiliary input signal. The multiple amplifiers are coupled in parallel to the RF input distribution network and configured to amplify the main and auxiliary input signals respectively by a main amplifier contributing a larger portion of the output power of the RF power amplifier and an auxiliary amplifier contributing a smaller portion of the output power of the RF amplifier. Each of the main and auxiliary amplifiers is selected from the amplifiers according to an impedance Z.sub.L of the transmit coil. A loading level of the main amplifier is modulated to alleviate loading mismatch condition of the main amplifier by adjusting current contributions from the main amplifier and the auxiliary amplifier according to the impedance Z.sub.L of the transmit coil. The signal combining network is configured to combine the main amplified signal and the auxiliary amplified signal into an output signal to drive the transmit coil.

An amplifier includes a semiconductor substrate. A first conductive feature partially covers the bottom substrate surface to define a conductor-less region of the bottom substrate surface. A first current conducting terminal of a transistor is electrically coupled to the first conductive feature. Second and third conductive features may be coupled to other regions of the bottom substrate surface. A first filter circuit includes an inductor formed over a portion of the top substrate surface that is directly opposite the conductor-less region. The first filter circuit may be electrically coupled between a second current conducting terminal of the transistor and the second conductive feature. A second filter circuit may be electrically coupled between a control terminal of the transistor and the third conductive feature. Conductive leads may be coupled to the second and third conductive features, or the second and third conductive features may be coupled to a printed circuit board.

Described is a phase-switched phase-switched, impedance modulation amplifier (PSIM). The PSIM has an input that can be coupled to a source and an output that can be coupled to a load. The PSIM includes one or more phase-switched reactive elements and a controller. The controller provides a control signal to each of the one or more phase-switched reactive elements. In response to one or more control signals provided thereto, each phase-switched reactive element provides a corresponding selected reactance value such that an impedance presented to an input or output port of an RF amplifier may be varied.

A method for improving the linearity of a radio frequency power amplifier, a compensation circuit (307) for implementing the method, and a communications terminal with the compensation circuit (307). In the method, a compensation circuit (307) is connected between a base (a3) and a collector (b3) of a transistor of a common emitter amplifier (306), in order to neutralize the impact of a variation in capacitance between the base (a3) and the collector (b3) of the transistor (306) according to a radio frequency signal. No additional direct-current power consumption is needed, and degradation in performance of other radio frequency power amplifiers can be avoided. The corresponding compensation circuit (307) can be easily integrated with a main amplification circuit, without affecting other performance of the main amplification circuit, and provides high adjustability.

In some implementations, there is provided an apparatus comprising a resonant amplifier circuit including a first inductor having a first inductive input and a first inductive output; a second inductor having a second inductive input and a second inductive output; a first switch coupled to the first inductive output; and a second switch coupled to the second inductive output, wherein the first switch and the second switched are driven out of phase, wherein the first inductor is configured to be resonant with a first capacitance associated with the first switch, and wherein the second inductor is configured to be resonant with a second capacitance associated with the second switch. Related systems and articles of manufacture are also provided.

An inductor includes first and second wirings respectively formed in a substantially spiral shape on first and second surfaces of a multilayer substrate. The multilayer substrate includes plural dielectric layers stacked on each other in a predetermined direction. The multilayer substrate includes a first layer having the first surface, which is an end surface in the predetermined direction, and a second layer having the second surface within the multilayer substrate. The width of the second wiring is smaller than that of the first wiring. The first and second wirings are electrically connected in parallel with each other. The inductance of the first wiring and that of the second wiring are substantially equal to each other. When the first and second wirings are projected on the first surface in the predetermined direction, entirety of a projected image of the second wiring is contained within that of the first wiring.