A power amplifier circuit includes a first transistor that amplifies a first signal and outputs a second signal; a second transistor that amplifies the second signal and outputs a third signal; a bias circuit that supplies a bias current to a base of the second transistor; and a bias adjustment circuit that adjusts the bias current by subjecting the first signal to detection. The bias adjustment circuit controls the bias current such that a first current extracted from the bias circuit depends on a magnitude of the first signal.

Circuits and methods for generating a bypass pulse to an RF circuit that increases the response time of the circuit to mode changes. Embodiments include a pulse generation circuit that it is self-initiated and self-terminated, generating a bypass pulse as a function of voltages V1 and V2 along a signal path. Voltage V3, a scaled version of V1, is compared to a voltage V4 derived from V2 and a pulse is output while V3>V4. The pulse temporarily lowers the signal path impedance, reducing the RC time constant of the signal path and allowing fast charging of components coupled to the signal path. The pulse may be used with any other circuit that needs a faster settling time after a mode change but is slowed down by an RC time constant. Usage also extends to providing for rapid discharge of the signal path by adding additional logic components.

Methods and apparatus for an amplifier including first and second transistors coupled in a stacked configuration with first and second current mirrors to provide respective bias signals to the amplifier transistors. A reference transistor is coupled to the first and second current mirrors for referencing the bias signals together.

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.

Apparatuses and systems implementing an amplifier module are described. The amplifier module can include a substrate. A driver amplifier die, a splitter network, an output amplifier die, a bias controller, and a combiner network can be coupled to the substrate. The driver amplifier die can be configured to receive an input radio frequency (RF) signal. The splitter network can be configured to split an intermediate RF signal outputted from the driver amplifier die into first and second RF signals. The output amplifier die can be configured to receive the first and second RF signals. The bias controller can be configured to bias the driver amplifier die and the output amplifier die. The combiner network can be configured to combine first and second outputs of the output amplifier die to generate an output RF signal and terminate at least one harmonic of the output amplifier die's output impedance.

Disclosed is a bidirectional amplifier. The bidirectional amplifier includes a first matching circuit, a second matching circuit, an amplifier circuit connected between the first matching circuit and the second matching circuit, that amplifies a first input signal received from the first matching circuit to output the amplified first input signal to the second matching circuit, and that amplifies a second input signal received from the second matching circuit to output the amplified first input signal to the first matching circuit, and the first and second matching circuits have a symmetrical structure and operate complementary to each other.

Various methods and circuital arrangements for biasing one or more gates of stacked transistors of an amplifier are possible where the amplifier is configured to operate in at least an active mode and a standby mode. Circuital arrangements can reduce bias circuit and stacked transistors standby current during operation in the standby mode and to reduce impedance presented to the gates of the stacked transistors during operation in the active mode while maintaining voltage compliance of the stacked transistors during both modes of operation.

A reconfigurable amplifier includes a first transistor having a gate coupled to an input of the reconfigurable amplifier, and a source coupled to a ground. The reconfigurable amplifier also includes a gate control circuit, and a second transistor having a gate coupled to the gate control circuit, a source coupled to a drain of the first transistor, and a drain coupled to an output of the reconfigurable amplifier, wherein the gate control circuit is configured to output a bias voltage to the gate of the second transistor in a cascode mode, and output a switch voltage to the gate of the second transistor in a non-cascode mode. The reconfigurable amplifier further includes a load coupled to the output of the reconfigurable amplifier.

A power amplifier circuit includes a first transistor configured to receive a first signal at a base, amplify the first signal, and output a second signal from a collector; and a bias circuit configured to supply a bias current to the base of the first transistor. The bias circuit includes a second transistor configured to supply a bias current to the base of the first transistor, a third transistor including a base connected to a base of the second transistor and a collector connected to a collector of the second transistor, and a fourth transistor including a base connected to an emitter of the third transistor and a collector connected to an emitter of the second transistor and configured to draw at least part of the bias current.

A low noise amplifier (LNA) includes a first transistor and a second transistor. A source of the second transistor is connected to a drain of the first transistor. The LNA further includes a feedback transformer. A gate of the first transistor is connected to a primary winding of the feedback transformer and a gate of the second transistor is connected to a secondary winding of the feedback transformer.