There is provided a RF-DAC that may include (i) a first PAM that includes a first group of first power amplifiers of different amplifications, (ii) a second PAM that includes a second group of second power amplifiers of different amplifications; (iii) a load that includes an output port and a transformer; (iv) power amplifiers control units, and a transformer control unit. During a cycle of operation (i) each one of the first and second PAMs is configured to receive one or more power amplifiers digital control signals and activate a single power amplifier per each of the first and second PAMS, (ii) the transformer control unit is configured to receive a transformer digital control signal and control a transformer parameter of the transformer, and (iii) the transformer is configured to receive a first PAM output signal and a second PAM output signal, and output a transformer output signal that reflects digital information represented by the one or more power amplifiers digital control signals and the transformer digital control signal.

According to one embodiment, a transformer-based in-phase and quadrature (IQ) includes a differential balun having a first inductor and a second inductor. The first inductor has a first input terminal and a first output terminal. The second inductor has a second input terminal and a second output terminal. Additionally, the IQ generator circuit includes a third inductor magnetically coupled with the first inductor. The third inductor has a first isolation terminal and a third output terminal. The IQ generator circuit also includes a fourth inductor magnetically coupled with the second inductor. The fourth inductor has a second isolation terminal and a fourth output terminal. The IQ generator circuit additionally includes a first transistor coupled to the first input terminal of the first inductor. Further, the generator circuit includes a second transistor coupled to the second input terminal of the second inductor. The first transistor, the second transistor, the first inductor, and the second inductor form a part of a differential amplifier.

Certain aspects of the present disclosure provide an amplifier. The amplifier generally includes an amplifier core circuit configured to amplify a radio frequency signal and having a first output and a second output; a transformer coupled to the amplifier core circuit, the transformer having a primary winding and a secondary winding, the primary winding being coupled to the first output and the second output of the amplifier core circuit, the secondary winding being coupled to an output node of the amplifier; and a variable resistance circuit coupled in parallel with the primary winding.

A power amplifier circuit includes: a power splitter; a first amplifier; a second amplifier; a first balun that splits a first amplified signal into a third amplified signal and a fourth amplified signal having a different phase from the third amplified signal; a third amplifier and a fourth amplifier that respectively amplify the third amplified signal and the fourth amplified signal; a second balun that splits a second amplified signal into a fifth amplified signal and a sixth amplified signal having a different phase from the fifth amplified signal; a fifth amplifier that amplifies the fifth amplified signal if a power level of the fifth amplified signal is equal to or higher than a predetermined power level; and a sixth amplifier that amplifies the sixth amplified signal if a power level of the sixth amplified signal is equal to or higher than a predetermined power level.

Systems and methods for differential antenna driving are provided. In one aspect, a front end system includes at least one power amplifier configured to receive a first transmit radio frequency signal from a baseband processor, amplify the first transmit radio frequency signal, and output the amplified first transmit radio frequency signal. The front end system further includes at least one balun configured to receive the amplified first transmit radio frequency signal. The at least one balun includes a positive output coupled to a first monopole of at least one antenna and a negative output coupled to a second monopole of the at least one antenna.

An electronic circuit includes a differential output circuit that produces a differential output signal at a differential output. A primary winding of a balun has a first balun terminal coupled to a first differential output terminal, and a second balun terminal coupled to a second differential output terminal. A configurable harmonic reduction circuit includes first and second configurable shunt capacitance circuits coupled between the first differential output terminal or the second differential output terminal, respectively, and a ground reference node. A control circuit receives tuning data associated with a calibrated tuning state. The tuning data indicates a first and second calibrated capacitance values, which are unequal, for the first and second configurable shunt capacitance circuits, respectively. The control circuit controls the first configurable shunt capacitance circuit to have the first calibrated capacitance value, and controls the second configurable shunt capacitance circuit to have the second calibrated capacitance value.

Apparatus and methods for power amplifiers with broadband matching networks are disclosed. In certain embodiments, a mobile device includes a transceiver that generates a radio frequency input signal, and a front-end system including a compound semiconductor die and a silicon switch die. The compound semiconductor die includes a power amplifier including one or more power amplifier stages that amplify the radio frequency input signal to generate a radio frequency output signal. The silicon switch die includes a band selection switch that receives the radio frequency output signal. The compound semiconductor die and the silicon switch die each include at least one controllable impedance for providing a bandwidth adjustment to the power amplifier.

The present invention discloses a matching circuit with switchable load lines, a load line switching method and a power amplifier. The matching circuit matches the output impedance of the power amplifier, which amplifies an input signal and outputs an amplified signal. The matching circuit comprises a filter circuit and a switch group for load line selection, the output end of the filter circuit is connected to the switch group. The switch group comprises at least two independent switches, each switch independently constitutes a signal line, and each switch is configured with an external control signal to control on/off. The matching circuit provided by the invention adopts a switch group composed of at least two independent switches, and each independent switch forms a signal line to connect loads, so that multiple loads can be connected at the same time.

A balun is disclosed and includes a dielectric substrate defining a first surface and a second surface. The balun includes a first output port including a first output ground portion and first output power portion; a second output port including a second output ground portion and a second output power portion; and an input port including an input ground portion and input power portion. The first output ground portion, the second output ground portion, and the input ground portion are coupled at a ground junction portion. The first output power portion, the second output power portion, and the input power portion are coupled at a power junction portion. The first output power portion, the second output power portion, and the input power portion are positioned on the first surface. The first output ground portion, the second output ground portion, and the input ground portion are positioned on the second surface.

A power amplifier, for a transmitter circuit is disclosed, which comprises at least one field-effect transistor having a gate terminal and a bulk terminal. The at least one field-effect transistor is configured to receive an input voltage at the gate terminal and a dynamic bias voltage at the bulk terminal. The power amplifier comprises a bias-voltage generation circuit configured to generate the dynamic bias voltage as a nonlinear function of an envelope of input signal. The input voltage is a linear function of the input signal. The bias-voltage generation circuit comprises a rectifier circuit configured to generate a rectified input voltage and an amplifier circuit, operatively connected to the rectifier circuit, configured to generate the dynamic bias voltage based on the rectified input voltage. The amplifier circuit is a variable-gain amplifier circuit and the power amplifier comprises a control circuit configured to tune the gain of the amplifier circuit.