355 results about "High power amplifier" patented technology

A technique for converting a non-sectorized cell to a sectorized cell having multiple sectors utilizing a single broadband processing unit. The spectrum of a given frequency band having a center frequency 'OMEGAo is divided into multiple bands (three, for example) having center frequencies 'OMEGAo, 'OMEGAo-alpha and 'OMEGAo+alpha. In the receive path, respective sub-bands are used to convey analog RF signals from a subscriber in respective sectors to an associated transceiver. Each of the transceivers includes a front end for receiving incoming RF signals and an analog-to-digital converter for converting the analog signal to a digital data stream. The digital data streams from transceivers are combined, i.e., processed by digitally adding, and supplied to a single channelizer which, in turn, supplies the data to a TDM bus for transmission to a PSTN network. In the reverse path from the PSTN network, TDM digital data signals emanating from a TDM bus are supplied to a combiner which feeds each of the respective transceivers which select the appropriate data from the combiner by digital filtering or processing. The transceivers convert the digital signal to analog form. After conversion, power amplifiers associated with the respective sectors effect emission of radiated power in the respective sectors. Advantageously, amplifiers in the sectorized improvement operate at lower power levels than the single high power amplifier of a non-sectorized cell, thereby providing substantial cost savings. More importantly, instead of deploying multiple broadband processing units the improved sectorized cell requires only a single broadband processing unit, thereby providing further economies.

An optical parametric oscillator (OPO) is described that efficiently converts a near-infrared laser beam to tunable mid-infrared wavelength output. In some embodiments, the OPO includes an optical resonator containing a nonlinear crystal, such as periodically-poled lithium niobate. The OPO is pumped by a continuous-wave fiber-laser source having a low-power oscillator and a high-power amplifier, or using just a power oscillator). The fiber oscillator produces a single-frequency output defined by a distributed-feedback (DFB) structure of the fiber. The DFB-fiber-laser output is amplified to a pump level consistent with exceeding an oscillation threshold in the OPO in which only one of two generated waves (“signal” and “idler”) is resonant within the optical cavity. This pump source provides the capability to tune the DFB fiber laser by straining the fiber (using an attached piezoelectric element or by other means) that allows the OPO to be continuously tuned over substantial ranges, enabling rapid, wide continuous tuning of the OPO output frequency or frequencies.

A transmitter providing a wide output control variable width with high efficiency is provided. Saturation mode operation is performed in the vicinity of the maximum transmission power and the input level of a large power amplifier is enlarged and fixed. When the large power amplifier is operated in a saturation state, the amplitude component of a modulation signal is input to an R input terminal in the range responsive to an output power control level and power supply voltage of a power supply terminal is amplitude-modulated, whereby highly efficient polar coordinate modulation is performed. In smaller transmission power, linear mode operation is performed, the input level of the large power amplifier is lessened for operating the large power amplifier in the linear mode, and the power supply voltage of the power supply terminal is made variable in response to the output power control level, whereby transmission power control is performed.