A multi-stage Radio Frequency (RF) power amplifier is presented herein. According to one embodiment, the amplifier comprises: a first amplification stage configured to amplify an input signal to provide a first output signal having a phase distortion; a second amplification stage having an input and configured to amplify the first output signal that is received at the input to provide a second output signal, wherein the second output signal has a carrier frequency (F.sub.C) modulated by a signal content (S) having a signal content bandwidth (F.sub.S); and a resonant circuit comprising an inductor and a capacitor and having a resonant frequency (F.sub.R), the resonant circuit coupled to the input of the second amplification stage and compensating for the phase distortion caused by the first amplification stage at frequencies within the signal content bandwidth F.sub.S, wherein the resonant frequency F.sub.R is less than the signal content bandwidth F.sub.S.

Apparatus and methods for radio frequency (RF) amplifiers are disclosed herein. In certain implementations, a packaged RF amplifier includes a first bipolar transistor including a base electrically connected to an RF input pin and a collector electrically connected to an RF output pin, and a second bipolar transistor including a base electrically connected to an emitter of the first bipolar transistor and a collector electrically connected to the RF output pin. The packaged RF amplifier further includes a first bias circuit electrically connected between the base of the first bipolar transistor and the RF output pin, a second bias circuit electrically connected between the base of the first bipolar transistor and a power low pin, an inductor implemented at least partly by a bond wire, and a third bias circuit electrically connected in series with the inductor between the base of the second bipolar transistor and the power low pin.

A semiconductor amplifier bias circuit includes a first transmission line, a first grounded capacitor, a second transmission line and a power supply terminal. The first transmission line is connected to an output end part of the output matching circuit and the external load. The second transmission line includes one end part connected to the first transmission line and the other end part connected to the first grounded shunt capacitor. An electrical length of the second transmission line is approximately 90 at a center frequency of a band. The one end part is connected to the first transmission line at a position apart from the output end part by an electrical length of approximately 45 at the center frequency. The power supply terminal is connected to a connection point of the first grounded shunt capacitor and the other end part of the second transmission line.

An active antenna module is disclosed. The active antenna module comprises a loop antenna, a RF transistor, a LR series circuit, a first bypass capacitor and a second bypass capacitor. The RF transistor comprises a control port, a first port, and a second port. Each of two ends of the loop antenna is electrically connected to one of the control port and the second port, and the control port and the second port are out of phase. The second port is electrically connected to the first port via the first bypass capacitor. The first port is electrically connected to ground via the LR series circuit. The second bypass capacitor and a resistor of the LR series circuit are connected in parallel.

An active antenna module is disclosed. The active antenna module comprises a loop antenna, a RF transistor, a LR series circuit, a first bypass capacitor and a second bypass capacitor. The RF transistor comprises a control port, a first port, and a second port. Each of two ends of the loop antenna is electrically connected to one of the control port and the second port, and the control port and the second port are out of phase. The second port is electrically connected to the first port via the first bypass capacitor. The first port is electrically connected to ground via the LR series circuit. The second bypass capacitor and a resistor of the LR series circuit are connected in parallel.

A peak detector for a power amplifier is provided that includes a threshold voltage detector configured to pulse a detection current in response to an amplified output signal from the amplifier exceeding a peak threshold. A plurality of such peak detectors may be integrated with a corresponding plurality of power amplifiers in a transmitter. Should any peak detector assert an alarm signal or more than a threshold number of alarm signals during a given period, a controller reduces a gain for the plurality of power amplifiers.

Apparatus and methods for radio frequency (RF) amplifiers are disclosed herein. In certain implementations, a packaged RF amplifier includes a first bipolar transistor including a base electrically connected to an RF input pin and a collector electrically connected to an RF output pin, and a second bipolar transistor including a base electrically connected to an emitter of the first bipolar transistor and a collector electrically connected to the RF output pin. The packaged RF amplifier further includes a first bias circuit electrically connected between the base of the first bipolar transistor and the RF output pin, a second bias circuit electrically connected between the base of the first bipolar transistor and a power low pin, an inductor implemented at least partly by a bond wire, and a third bias circuit electrically connected in series with the inductor between the base of the second bipolar transistor and the power low pin.

Apparatus and methods for radio frequency (RF) amplifiers are disclosed herein. In certain implementations, a packaged RF amplifier includes a first bipolar transistor including a base electrically connected to an RF input pin and a collector electrically connected to an RF output pin, and a second bipolar transistor including a base electrically connected to an emitter of the first bipolar transistor and a collector electrically connected to the RF output pin. The packaged RF amplifier further includes a first bias circuit electrically connected between the base of the first bipolar transistor and the RF output pin, a second bias circuit electrically connected between the base of the first bipolar transistor and a power low pin, an inductor implemented at least partly by a bond wire, and a third bias circuit electrically connected in series with the inductor between the base of the second bipolar transistor and the power low pin.

A direct current (DC)-DC converter, which includes a charge pump buck power supply and a buck power supply is disclosed. The charge pump buck power supply includes a charge pump buck converter, a first inductive element, and an energy storage element. The charge pump buck converter and the first inductive element are coupled in series between a DC power supply, such as a battery, and the energy storage element. The buck power supply includes a buck converter, a second inductive element, and the energy storage element. The buck converter and the second inductive element are coupled in series between the DC power supply and the energy storage element. As such, the charge pump buck power supply and the buck power supply share the energy storage element.

A direct current (DC)-DC converter, which includes a charge pump buck power supply and a buck power supply is disclosed. The charge pump buck power supply includes a charge pump buck converter, a first inductive element, and an energy storage element. The charge pump buck converter and the first inductive element are coupled in series between a DC power supply, such as a battery, and the energy storage element. The buck power supply includes a buck converter, a second inductive element, and the energy storage element. The buck converter and the second inductive element are coupled in series between the DC power supply and the energy storage element. As such, the charge pump buck power supply and the buck power supply share the energy storage element.