A matching circuit includes first and second ports, an autotransformer, and first and second capacitors. The autotransformer includes a first terminal coupled to a first port, a second terminal coupled to a second port, and a common terminal coupled to a reference potential, and includes a series parasitic inductor and a parallel parasitic inductor. The first capacitor is coupled in shunt to the second terminal, and defines a low pass filter together with the series parasitic inductor. The second capacitor is coupled in series between the first port and the first terminal, and defines a high pass filter together with the parallel parasitic inductor.

A power amplifier circuit includes a power amplifier, first and second filters, and first and second output paths. The power amplifier is able to amplify both of a first signal and a second signal. The frequency of the second signal is higher than that of the first signal. The first filter includes a first inductor and attenuates the second signal amplified in the power amplifier. The first inductor serves as a path for the first signal amplified in the power amplifier. The second filter includes a first capacitor and attenuates the first signal amplified in the power amplifier. The first capacitor serves as a path for the second signal amplified in the power amplifier. The first signal outputted from the first filter is supplied to the first output path. The second signal outputted from the second filter is supplied to the second output path.

Methods and devices used in mobile receiver front end to support multiple paths and multiple frequency bands are described. The presented devices and methods provide benefits of scalability, frequency band agility, as well as size reduction by using one low noise amplifier per simultaneous outputs. Based on the disclosed teachings, variable gain amplification of multiband signals is also presented.

An amplifying system is provided for use as a high sensitivity receive booster or replacement for a low noise amplifier in a receive chain of a communication device. The amplifying system includes an amplifying circuit configured to receive an input signal having a first frequency and generate an oscillation based on the input signal, a sampling circuit coupled to the amplifying circuit and configured to terminate the oscillation based on a predetermined threshold to periodically clamp and restart the oscillation to generate a series of pulses modulated by the oscillation and by the input signal, and one or more resonant circuits coupled with the amplifying circuit and configured to establish a frequency of operation and to generate an output signal having a second frequency, the second frequency being substantially the same as the first frequency.

A logarithmic detector amplifying (LDA) system is provided for use as a high sensitivity receive booster or replacement for a low noise amplifier in a receive chain of a communication device. The LDA system includes an amplifying circuit configured to receive an input signal having a first frequency and generate an oscillation based on the input signal, a sampling circuit coupled to the amplifying circuit and configured to terminate the oscillation based on a predetermined threshold to periodically clamp and restart the oscillation to generate a series of pulses modulated by the oscillation and by the input signal, and one or more metamaterial (“MTM”) resonant circuits coupled in shunt with an RF path that couples the amplifying circuit in series and configured to establish a frequency of operation and a phase response to output a signal having RF frequencies with a ultra-wide bandwidth.

A power amplifier circuit includes a power amplifier, first and second filters, and first and second output paths. The power amplifier is able to amplify both of a first signal and a second signal. The frequency of the second signal is higher than that of the first signal. The first filter includes a first inductor and attenuates the second signal amplified in the power amplifier. The first inductor serves as a path for the first signal amplified in the power amplifier. The second filter includes a first capacitor and attenuates the first signal amplified in the power amplifier. The first capacitor serves as a path for the second signal amplified in the power amplifier. The first signal outputted from the first filter is supplied to the first output path. The second signal outputted from the second filter is supplied to the second output path.

A matching circuit includes first and second ports, an autotransformer, and first and second capacitors. The autotransformer includes a first terminal coupled to a first port, a second terminal coupled to a second port, and a common terminal coupled to a reference potential, and includes a series parasitic inductor and a parallel parasitic inductor. The first capacitor is coupled in shunt to the second terminal, and defines a low pass filter together with the series parasitic inductor. The second capacitor is coupled in series between the first port and the first terminal, and defines a high pass filter together with the parallel parasitic inductor.

An amplifying system is provided for use as a high sensitivity receive booster or replacement for a low noise amplifier in a receive chain of a communication device. The amplifying system includes an amplifying circuit configured to receive an input signal having a first frequency and generate an oscillation based on the input signal, a sampling circuit coupled to the amplifying circuit and configured to terminate the oscillation based on a predetermined threshold to periodically clamp and restart the oscillation to generate a series of pulses modulated by the oscillation and by the input signal, and one or more resonant circuits coupled with the amplifying circuit and configured to establish a frequency of operation and to generate an output signal having a second frequency, the second frequency being substantially the same as the first frequency.

A power amplifier circuit is provided, to improve efficiency of a power amplifier. The circuit includes: a first branch, including a first amplifier and a first matching network that are cascaded; a second branch, including a second amplifier and a second matching network that are cascaded, where a first coupled line enables the first branch and the second branch to form a first combiner; a third branch, including a third amplifier and a third matching network that are cascaded; and a fourth branch, including a fourth amplifier and a fourth matching network that are cascaded, where a second coupled line enables the third branch and the fourth branch to form a second combiner. A first output end of the first coupled line is a signal output end of the circuit, and a second output end of the first coupled line is connected to a first output end of the second coupled line, to enable the first combiner and the second combiner to form a series combiner.

An amplifier includes a transistor, an input circuit coupled between an amplifier input and a transistor input terminal, and an output circuit coupled between a transistor output and a transistor output terminal. The input circuit includes an input-side harmonic termination circuit with a first inductor and a first capacitance in series between the transistor input terminal and ground. The output circuit includes a second inductor, an output-side harmonic termination circuit, and a shunt-L circuit. The second inductor is coupled between the transistor output terminal and the amplifier output. The output-side harmonic termination circuit includes a third inductor and a second capacitance in series between the amplifier output and ground. The shunt-L circuit includes a fourth inductor and a third capacitance connected in series between the amplifier output and ground. The input-side and output-side harmonic termination circuits resonate at a harmonic frequency of a fundamental frequency of operation of the amplifier.