微波及毫米波四次諧波混頻器
微波及毫米波四次諧波混頻器
The power amplifier, an indispensable component in most wireless communication systems, is inherently nonlinear. In view of the importance of video conferencing and internetworking features to the next generation of mobile terminals (e.g. mobile phones) as well as the demand for high data rate transmission, the past decade has seen intensive research efforts spent on high linear amplification systems for high bandwidth-efficient modulation formats like CDMA, OFDMA and QAM. However, most of the conventional wideband linearization techniques available involve complicated and expensive circuitry. They are only suitable for base stations, and are not cost-effective for portable devices. To guarantee that the operation of mobile terminals meet tough regulations, the simplest way is to back-off output power so that the power amplifier is operating within the linear region. However, the lifetime of the battery will be shortened, as most of the DC power is dissipated as heat.
This invention is a novel bipolar junction transistor (BJT) power amplifier topology with both linearity improvement and efficiency enhancement for portable devices. The linearizer mainly consists of a diode, an inductor, a capacitor and a resistor. It is the integration of a baseband distortion return path and an adaptive bias network. The former is for reducing low frequency even-order intermodulation products, thereby suppressing spectral regrowth. The latter is for stabilizing the DC base-emitter bias voltage and for supplying an adaptive collector current to the amplifying transistor. The adaptive current, a low DC current, is supplied for small-signal amplification, and is then increased with the increase of input power. Therefore, the DC biasing power can be adaptively managed.
Mobile phones/terminals and many consumer electronic appliances.
28/12/2005
ZL02107141.1
香港
