A wide modulation bandwidth radio frequency (RF) circuit is provided. In examples discussed herein, the RF front-end circuit includes a tracker circuit configured to generate a modulated voltage at a wide modulation bandwidth. The modulated voltage can be used by an amplifier circuit(s) for amplifying an RF signal(s). Notably, the tracker circuit may have inherent frequency-dependent impedance that can interact with a load current of the amplifier circuit(s) to cause degradation in the modulated voltage, which can further lead to distortions in an RF offset spectrum. In this regard, a notch circuit is provided and configured to operate at an appropriate notch frequency and a notch bandwidth to filter the modulated voltage in the RF offset spectrum. As a result, it may be possible to reduce the distortions caused by the modulated voltage degradation in the RF offset spectrum, thus helping to improve linearity and efficiency of the amplifier circuit(s).

An apparatus for and method of a supply modulator (SM) for a power amplifier (PA) is provided. The apparatus includes a buck-boost converter, including a supply input connected to a battery voltage (Vbat), and an output; and a buck converter, including a supply input connected to Vbat, an input connected to the output of the buck-boost converter, and an output.

Disclosed is the audio amplifier comprising an input for an audio signal to be amplified and an output for powering a load on the basis of the amplified audio signal; a generator of reference voltage of very high linearity and low output impedance, able to receive, as input, the audio signal to be amplified; a power current generator comprising a power voltage generator whose output is connected to the output of the reference voltage generator through a coupling impedance. The coupling impedance comprises two coupling inductances mounted in series between the output of the reference generator and the output of the power voltage generator and an attenuation impedance linking a mid-point between the two coupling inductances and a reference potential, wherein the attenuation impedance includes an attenuation inductance.

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.

A single-stage amplifier circuit includes first and second transistors (e.g., BJTs or FETs) connected in parallel between the amplifier's input and output nodes. The first and second transistors are configured differently using known fabrication techniques such that a (first) cutoff frequency of the first transistor is at least 1.5 times greater than a (second) cutoff frequency of the second transistor, and such that a ratio of the respective cutoff frequencies produces a significant cancellation of second derivative transconductance (Gm) in the amplifier output signal, whereby the amplifier achieves significantly improved IIP.sub.3. Alternatively, the amplifier is configured using MOSFETs having respective different channel lengths to achieve the desired cutoff frequency ratio. An exemplary communication circuit includes a low-noise amplifier having two NPN BJTs that are fabricated using different collector doping concentrations, different emitter doping concentrations, or different base region widths in order to achieve the desired cutoff frequency ratio.

This application relates to Class D amplifier circuits (200). A modulator (201) controls a Class D output stage (202) based on a modulator input signal (Dm) to generate an output signal (Vout) which is representative of an input signal (Din). An error block (205), which may comprise an ADC (207), generates an error signal () from the output signal and the input signal. In various embodiments the extent to which the error signal () contributes to the modulator input signal (Dm) is variable based on an indication of the amplitude of the input signal (Din). The error signal may be received at a first input (204) of a signal selector block (203). The input signal may be received at a second input (206) of the signal selector block (203). The signal selector block may be operable in first and second modes of operation, wherein in the first mode the modulator input signal is based at least in part on the error signal; and in the second mode the modulator input signal is based on the digital input signal and is independent of the error signal. The error signal can be used to reduce distortion at high signal levels but is not used at low signal levels and so the noise floor at low signal levels does not depend on the component of the error block (205).

A single-stage amplifier circuit includes first and second transistors (e.g., BJTs or FETs) connected in parallel between the amplifier's input and output nodes. The first and second transistors are configured differently using known fabrication techniques such that a (first) cutoff frequency of the first transistor is at least 1.5 times greater than a (second) cutoff frequency of the second transistor, and such that a ratio of the respective cutoff frequencies produces a significant cancellation of second derivative transconductance (Gm) in the amplifier output signal, whereby the amplifier achieves significantly improved IIP.sub.3. Alternatively, the amplifier is configured using MOSFETs having respective different channel lengths to achieve the desired cutoff frequency ratio. An exemplary communication circuit includes a low-noise amplifier having two NPN BJTs that are fabricated using different collector doping concentrations, different emitter doping concentrations, or different base region widths in order to achieve the desired cutoff frequency ratio.

A radio frequency (RF) power combining amplifier circuit has a circuit input and a circuit output. A first amplifier is connected to the circuit input and to a first bias input. A first output matching network is connected to an output of the first amplifier and to the circuit output. A second amplifier is connected to the circuit input and to a second bias input. A second output matching network is connected to an output of the second amplifier, and to the circuit output. A voltage level of an input signal applied to the circuit input, together with the respective first bias input and the second bias input, selectively activates the first amplifier and the second amplifier.

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.

A wide modulation bandwidth radio frequency (RF) circuit is provided. In examples discussed herein, the RF front-end circuit includes a tracker circuit configured to generate a modulated voltage at a wide modulation bandwidth. The modulated voltage can be used by an amplifier circuit(s) for amplifying an RF signal(s). Notably, the tracker circuit may have inherent frequency-dependent impedance that can interact with a load current of the amplifier circuit(s) to cause degradation in the modulated voltage, which can further lead to distortions in an RF offset spectrum. In this regard, a notch circuit is provided and configured to operate at an appropriate notch frequency and a notch bandwidth to filter the modulated voltage in the RF offset spectrum. As a result, it may be possible to reduce the distortions caused by the modulated voltage degradation in the RF offset spectrum, thus helping to improve linearity and efficiency of the amplifier circuit(s).