An on-chip transformer circuit is disclosed. The on-chip transformer circuit comprises a primary winding circuit comprising at least one turn of a primary conductive winding arranged as a first N-sided polygon in a first dielectric layer of a substrate; and a secondary winding circuit comprising at least one turn of a secondary conductive winding arranged as a second N-sided polygon in a second, different, dielectric layer of the substrate. In some embodiments, the primary winding circuit and the secondary winding circuit are arranged to overlap one another at predetermined locations along the primary conductive winding and the secondary conductive winding, wherein the predetermined locations comprise a number of locations less than all locations along the primary conductive winding and the secondary conductive winding.

A high-frequency circuit includes a power amplifier for a communication band A, and a power amplifier for a communication band B. Transmission in the communication band A, transmission in the communication band B, and reception in the communication band C can be simultaneously used. A frequency range of intermodulation distortion generated between a second harmonic wave of a transmission signal of the communication band A and a fundamental wave of a transmission signal of the communication band B, overlaps with at least part of a reception band of the communication band C. The power amplifier includes amplifying elements and an output trans including coils. One end of the coil is connected with an output of the amplifying element, the other end of the coil is connected with an output of the amplifying element, and one end of the coil is connected with an output terminal of the power amplifier.

A power amplifier comprises a first amplification stage having an input terminal receiving a radio frequency (RF) signal to be amplified and having a first coupling unit, a second amplification stage outputting an amplified radio frequency signal and having a second coupling unit and a third coupling unit providing RF feedback to the input terminal of the first amplification stage through an RF feedback path, the second coupling unit being coupled to the first coupling unit, and the third coupling unit being coupled to the first coupling unit.

A radio frequency module includes: a module board that includes a first principal surface and a second principal surface on opposite sides of the module board; a power amplifier configured to amplify a transmission signal; a first circuit component; and a power amplifier (PA) control circuit configured to control the power amplifier. The power amplifier and the PA control circuit are stacked on the first principal surface, and the first circuit component is disposed on the second principal surface.

An active biconical antenna and a receive array comprising a combination of active biconical and Vivaldi antennas. In one configuration, the active biconical antenna includes upper and lower cones. Each cone has a respective truncated apex. First and second feed points are respectively connected to the truncated apexes of the upper and lower cones and to first and second conductors. The active biconical antenna further includes a buffer amplifier having respective input terminals connected to the first and second conductors. The buffer amplifier has an input impedance that is impedance matched to an antenna impedance at and above but not below a frequency f.sub.c and is higher than the antenna impedance at frequencies substantially less than f.sub.c. The buffer amplifier also has an output impedance that is impedance matched to a system impedance at frequencies both above and below f.sub.c. A length of the first and second conductors is less than a wavelength at the frequency f.sub.c.

In many examples, a device comprises a transmitter. The transmitter comprises a power amplifier, a first transformer coil coupled to the power amplifier, and a second transformer coil adapted to be electromagnetically coupled to the first transformer coil. The transmitter also comprises a first bond wire coupled to a first end of the second transformer coil and adapted to be coupled to a first end of an antenna, a capacitor coupled to a second end of the second transformer coil, a switch coupled to the capacitor and configured to engage and disengage the capacitor from the transmitter, and a second bond wire coupled to the switch and adapted to be coupled to a second end of the antenna.

A system and method which includes receiving an input signal and providing, by an amplifier circuit, an output signal in response to the input signal, the output signal having an envelope. An envelope detection signal corresponding to the envelope of the output signal is generated. A bias current provided to an amplifier circuit is adjusted based upon the envelope detection signal. The amplifier circuit includes an amplifier and a transformer, the transformer being configured to establish a magnetically coupled feedback loop from an output of the amplifier to an input of the amplifier.

An uplink multiple input-multiple output (MIMO) transmitter apparatus includes a transmitter chain that includes a sigma-delta circuit that creates a summed (sigma) signal and a difference (delta) signal from two original signals to be transmitted. These new sigma and delta signals are amplified by power amplifiers to a desired output level before having two signals reconstructed from the amplified sigma and amplified delta signals by a second circuit. These reconstructed signals match the two original signals in content but are at a desired amplified level relative to the two original signals. The reconstructed signals are then transmitted through respective antennas as uplink signals. By employing this uplink MIMO transmitter apparatus, it is possible to use smaller power amplifiers, which may reduce footprint, power consumption, and costs of the uplink MIMO transmitter apparatus.

An active biconical antenna and a receive array comprising a combination of active biconical and Vivaldi antennas. In one configuration, the active biconical antenna includes upper and lower cones. Each cone has a respective truncated apex. First and second feed points are respectively connected to the truncated apexes of the upper and lower cones and to first and second conductors. The active biconical antenna further includes a buffer amplifier having respective input terminals connected to the first and second conductors. The buffer amplifier has an input impedance that is impedance matched to an antenna impedance at and above but not below a frequency f.sub.c and is higher than the antenna impedance at frequencies substantially less than f.sub.c. The buffer amplifier also has an output impedance that is impedance matched to a system impedance at frequencies both above and below f.sub.c. A length of the first and second conductors is less than a wavelength at the frequency f.sub.c.

A radio frequency circuit includes a transmit power amplifier, a differential transmit signal path having first and second paths, and first and second baluns. The first balun can be configured to convert a single ended transmit signal into a differential transmit signal, and the second balun can be configured to convert the differential transmit signal back to a single ended transmit signal. The circuit can also include a pair of transmit filters between the first and second baluns and including a first transmit filter connected in the first path and a second transmit filter connected in the second path. The second balun cancels harmonic noise generated by the pair of transmit filters.