Abstract: Two PIFAs substantially perpendicular to each other have feed points facing each other and ends connected. A phase transformer is coupled to one of the PIFAs to produce a phase difference of 90 degrees in electric fields generated by these two PIFAs so as to generate circular polarized waves.

Abstract: A bias circuit for a radio frequency power amplifier includes a bias transistor having a collector, an emitter, and a base, wherein the collector is connected to a DC voltage source, the emitter is connected to a radio frequency transistor, and the base is connected to a bias voltage source. An inductor is connected between the base of the radio frequency transistor and the emitter of the bias transistor, for blocking part of a radio frequency input signal coupled back to the bias transistor. A capacitor is connected between the base of the bias transistor and ground, for directly conducting the part of the radio frequency input signal coupled back to the bias transistor, into the ground, thereby preventing the bias transistor from being driven into a saturation state.

Abstract: A radio frequency (RF) power amplifier module integrated with a power control loop is formed on a print circuit board and packaged within a mold. In order to minimize a whole size of the RF power amplifier module, capacitors with a smaller size are employed to substitute for prior art ceramic directional couplers. In addition to the capacitors, RF power amplifiers, matching circuits, power detectors, and a power control specific application integrated circuit are all integrated on the print circuit board without individual packages. Furthermore, the RF power amplifiers and the power detectors are formed on a common semiconductor substrate. Therefore, the RF power amplifier module has advantages of a small size and minimum parasitic impedance.

Abstract: The invention discloses a method for detecting defectives in an integrated circuit. The integrated circuit is composed of a plurality of transistors in parallel on a wafer. The method includes the following two steps: applying a bias to the transistors, and extracting the infrared images of the transistors.

Abstract: A bias circuit for a radio frequency power amplifier includes a bias transistor having a collector, an emitter, and a base, wherein the collector is connected to a DC voltage source, the emitter is connected to a radio frequency transistor, and the base is connected to a bias voltage source. An inductor is connected between the base of the radio frequency transistor and the emitter of the bias transistor, for blocking part of a radio frequency input signal coupled back to the bias transistor. A capacitor is connected between the emitter of the bias transistor and ground or between the base of the bias transistor and ground, for directly conducting the part of the radio frequency input signal coupled back to the bias transistor, into the ground, thereby preventing the bias transistor from being driven into a saturation state.

Abstract: A radio frequency (RF) power amplifier module integrated with a power control loop is formed on a print circuit board and packaged within a mold. In order to minimize a whole size of the RF power amplifier module, capacitors with a smaller size are employed to substitute for prior art ceramic directional couplers. In addition to the capacitors, RF power amplifiers, matching circuits, power detectors, and a power control specific application integrated circuit are all integrated on the print circuit board without individual packages. Furthermore, the RF power amplifiers and the power detectors are formed on a common semiconductor substrate. Therefore, the RF power amplifier module has advantages of a small size and minimum parasitic impedance.