A transistor stack can include a combination of floating and body tied devices. Improved performance of the RF amplifier can be obtained by using a single body tied device as the input transistor of the stack, or as the output transistor of the stack, while other transistors of the stack are floating transistors. Transient response of the RF amplifier can be improved by using all body tied devices in the stack.

A frontend circuit includes a wide-band filter, a transmit filter, and switches. The wide-band filter passes both the receive frequency band of a first communication frequency band and that of a second communication frequency band which is close to or overlaps that of the first communication frequency band. The transmit filter passes the transmit frequency band of the first or second communication frequency band. The switches are capable of simultaneously bringing, into conduction, at least two of multiple filters including the wide-band filter and the transmit filter. In carrier aggregation using the receive frequency bands of the first and second communication frequency bands, the switches simultaneously bring the wide-band filter and the transmit filter into conduction. Thus, in carrier aggregation using signals of multiple communication frequencies simultaneously in communication, attenuation of signals due to signal leakage in two receive frequency bands, which are close to each other, is suppressed.

A frontend circuit includes a wide-band filter, a transmit filter, and switches. The wide-band filter passes both the receive frequency band of a first communication frequency band and that of a second communication frequency band which is close to or overlaps that of the first communication frequency band. The transmit filter passes the transmit frequency band of the first or second communication frequency band. The switches are capable of simultaneously bringing, into conduction, at least two of multiple filters including the wide-band filter and the transmit filter. In carrier aggregation using the receive frequency bands of the first and second communication frequency bands, the switches simultaneously bring the wide-band filter and the transmit filter into conduction. Thus, in carrier aggregation using signals of multiple communication frequencies simultaneously in communication, attenuation of signals due to signal leakage in two receive frequency bands, which are close to each other, is suppressed.

A circuit for biasing a transistor is provided. The circuit includes an output terminal configured to be coupled to a gate terminal of the transistor and circuitry. In a first state, the circuitry is configured to output a control signal at a first voltage level for setting the transistor to a first transistor state. In a second state, the circuitry is configured to first output the control signal at a second voltage level different from the first voltage level following by changing the control signal from the second voltage level towards a third voltage level different from the first and second voltage level over time.

A radio frequency power amplifier circuit includes a controllable attenuation circuit, an input matching circuit, a drive amplification circuit, an inter-stage matching circuit, a power amplification circuit and an output matching circuit connected in sequence, and respectively configured to switch between a negative gain mode and a non-negative gain mode of the radio frequency power amplifier circuit based on a mode control signal, match the impedance between the controllable attenuation circuit and the drive amplification circuit, amplify a signal, configured to match the impedance between the drive amplification circuit and the power amplification circuit, amplify a signal, and match the impedance between the radio frequency power amplifier circuit and a post-stage circuit. A feedback circuit is connected across the drive amplification circuit, and is configured to adjust a gain.

A calculation device includes a memory and a processor coupled to the memory. The processor is configured to; in an amplifier circuit including an input terminal to which a radio frequency signal is input, a transistor configured to amplify the input radio frequency signal, an output terminal from which the amplified radio frequency signal is output, and a matching circuit connected between the transistor and the output terminal, calculate a radio frequency characteristic of the amplifier circuit, if the calculated radio frequency characteristic of the amplifier circuit is a desired characteristic, calculate, at least one value of a current value and a voltage value at a predetermined portion within the equivalent circuit, and calculate, the deterioration degree of the electric characteristic of the transistor.

In certain examples, methods and semiconductor structures are directed to a switching (power) amplification circuit, including resonance circuitry to resonate at a frequency associated with at least one of a plurality of different selectable resonance frequencies. The switching amplification circuit is configured to deliver power to one or multiple loads while the switching amplifier circuit is operating based on one or more of the selectable resonance frequencies.

Amplification circuitry is disclosed that couples neutralization transistors to amplification transistors to neutralize parasitic capacitance of the amplification transistors. Gates of a first amplification transistor and a first neutralization transistor are coupled together, and gates of a second amplification transistor and a second neutralization transistor are also coupled together. Drains of the first amplification transistor and the second neutralization transistor are coupled together, and drains of the second amplification transistor and the first neutralization transistor are also coupled together. Sources of neutralization transistors are coupled together at a node, such that a voltage swing of a first signal in the first neutralization transistor may be canceled by a voltage swing of a second signal in the second neutralization transistor. The node also couples to a resistor that prevents charge building in the neutralization transistors.

An analog front-end (AFE) device and method for a high baud-rate receiver. The device can include an input matching network coupled to a first buffer device, which is coupled to a sampler array. The input matching network can include a first T-coil configured to receive a first input and a second T-coil configured to receive a second input. The first buffer device can include one or more buffers each having a bias circuit coupled to a first class-AB source follower and a second class-AB source follower. The sampling array can include a plurality of sampler devices configured to receive a multi-phase clocking signal. Additional optimization techniques can be used, such as having a multi-tiered sampler array and having the first buffer device configured with separate buffers for odd and even sampling phases. Benefits of this AFE configuration can include increased bandwidth, sampling rate, and power efficiency.

The invention relates to a resonator circuit, the resonator circuit comprising a transformer comprising a primary winding and a secondary winding, wherein the primary winding is inductively coupled with the secondary winding, a primary capacitor being connected to the primary winding, the primary capacitor and the primary winding forming a primary circuit, and a secondary capacitor being connected to the secondary winding, the secondary capacitor and the secondary winding forming a secondary circuit, wherein the resonator circuit has a common mode resonance frequency at an excitation of the primary circuit in a common mode, wherein the resonator circuit has a differential mode resonance frequency at an excitation of the primary circuit in a differential mode, and wherein the common mode resonance frequency is different from the differential mode resonance frequency.