91results about How to "Reduce noise figure" patented technology

A system and method for converting a non-cognitive radio into a cognitive radio is presented. A cognitive radio system includes, a non-cognitive radio; an electronic device, a spectrum sensing logic and configuration and management logic. The electronic device is connected to the non-cognitive radio so that it receives and / or transmits messages to / from a wireless network. The configuration and management logic is connected between the non-cognitive radio and the spectrum sensing logic. The spectrum sensing logic and the configuration and management logic are removable from the non-cognitive radio allowing the cognitive radio to operate in a non-cognitive mode. The spectrum sensing logic senses a wireless environment to determine available frequencies and available channels. The configuration and management logic transmits available frequencies, available channels or other spectrum data to a remote spectrum manager that is managing access to the wireless network.

A buffer layer made of i-GaAs not doped with impurities, and an n+ GaAs layer doped with a high-concentration of n-type impurities are stacked in the order named on a semi-insulating GaAs substrate. An n− GaAs layer doped with a low-concentration of n-type impurities is partially located on the n+ GaAs layer. Cathode electrodes are located in opening regions in which the n− GaAs layer is not present on the n+ GaAs layer. An anode electrode is located on the n− GaAs layer. The n+ GaAs layer has a carrier concentration of 5×1018 cm−3, and is in ohmic contact with the cathode electrodes. The n− GaAs layer has a carrier concentration of 1.2×1017 cm−3, and is in Schottky contact with the anode electrode.

The present invention is an amplifier circuit that permits variable gain control, comprising an input terminal to which a high frequency input signal is supplied; an amplifier transistor to the gate of which the high frequency input signal supplied to the input terminal is supplied and which generates an amplified signal at the drain side; and a variable attenuator provided in a signal transmission line between the input terminal and the gate of the amplifier transistor, in which a plurality of attenuation units in which an attenuation capacitor and a switch transistor are serially connected are provided in parallel between the signal transmission line and a power supply, and the attenuation ratio of which is variably controlled by controlling the conduction of the switch transistor.

Optical telecommunications system, comprising: a station (1) for transmitting optical signals, comprising a transmission signal generator (2), capable of generating at least two signals at wavelengths lying within a band of predetermined width, and a multiplexer (3) of the optical signals; a station (8) for receiving the optical signals; and an optical fibre line connecting the said multiplexer of the transmission station to the receiving station. The optical fibre line includes at least one optical amplifier (7) comprising at least one fibre (12) doped with a rare earth, at least one source of pumping radiation (14) for the said doped fibre, and a gain stabilization circuit. The gain stabilization circuit comprises: a separator of the transmission signals from the spontaneous emission of the amplifier, connected after the doped fibre and capable of sending the transmission signals to the output of the amplifier and the spontaneous emission to a further output, and a loop circuit for the re-circulation of the said spontaneous emission collected from the said further output and re-injected before the said doped fibre of the amplifier.

A front-end circuit of the wireless transceiver is disclosed to reduce the number of the pin count of the chip, and achieve the impedance matching. The circuit comprises an antenna unit, a receiver, and a transmitting block, all of which are connected together, wherein there is no switch provided between the receiver and the antenna unit, such that the loss of switch can be avoided for reducing the noise figure and improve the sensitivity of the receiving path accordingly.

In a system and method for simultaneously receiving or switching between dual frequency carrier signals in a GPS receiver, the GPS receiver is adapted to utilize different harmonics of a sub-harmonic frequency generator, which may include a lower frequency voltage controlled oscillator (VCO) to detect the L1 and L2 GPS carriers. A sub-harmonic mixer may be used to simultaneously down convert the L1 and L2 signals to a lower intermediate frequency (IF). A second mixer may be an image reject (IR) mixer used to separate the downconverted L1 and L2 signals. This mixer may be configured to simultaneously monitor the L1 and L2 signals, or to switch between the L1 and L2 signals. High frequency switching is not required of the radio frequency (RF) input or local oscillator signals, and simultaneous L1 and L2 reception is enabled without a 3 dB image noise degradation. This system and method minimizes the RF components and power dissipation in a dual frequency GPS receiver, while optimizing the functionality and performance.

The present invention is an amplifier circuit that permits variable gain control, comprising an input terminal to which a high frequency input signal is supplied; an amplifier transistor to the gate of which the high frequency input signal supplied to the input terminal is supplied and which generates an amplified signal at the drain side; and a variable attenuator provided in a signal transmission line between the input terminal and the gate of the amplifier transistor, in which a plurality of attenuation units in which an attenuation capacitor and a switch transistor are serially connected are provided in parallel between the signal transmission line and a power supply, and the attenuation ratio of which is variably controlled by controlling the conduction of the switch transistor.

The invention discloses an adjustable grain low noise amplifier which is a cascode. The adjustable grain low noise amplifier comprises a grain adjusting control circuit, a load circuit, a current guiding circuit and an input circuit, wherein the grain adjusting control circuit is used for receiving a grain adjusting voltage and further generating a resistance value adjusting signal and a current guiding control signal; the load circuit comprises a plurality of variable resistors and is used for adjusting the resistance values of the plurality of the variable resistors according to the resistance values; the current guiding circuit is connected to the load circuit through a plurality of current paths and is used for adjusting the current ratios among the plurality of current paths according to the current guiding control signal and the current guiding circuit is provided with a differential signal output end; and the input circuit is connected to the current guiding circuit, wherein the input circuit is provided with a differential signal input end. The amplifier can provide low noise index during low grain and provide wider grain adjusting range, and further achieve lower power loss, smaller layout area, lower linearity requirement and other effects.

A radio relay apparatus including an outdoor relay unit formed of first and second receiving parts equipped out of doors and an indoor relay unit formed of third and fourth receiving parts, and a digital transmission line connecting the outdoor and indoor relay units enables radio communication even in a blind area such as an underground area and tunnel. In the first receiving part of the outdoor relay unit, a receiving antenna for receiving a high-frequency signal is integrally incorporated so as eliminate the transmission loss. The high-frequency analog signal is converted to its corresponding digital signal of a desired frequency band by a digital signal processor in the outdoor relay unit, and then, the digital signal thus obtained is transmitted to the indoor relay unit through the digital transmission line, so that high-quality radio communication can be accomplished.

The invention discloses a pump integrated optical device comprising a first two-core glass pin, a first collimating optical lens, a gain flatness filter assembly, a second collimating optical lens, and a second two-core glass pin which are arranged in the inside sealed glass tube from left to right, and a metal outside sealed tube which is arranged outside the inside sealed glass tube. An isolator chipware is placed at the front end or the tail end of the gain flatness filter assembly. The first collimating optical lens and the second collimating optical lens are provided with filter membranes which can transmit signal light and reflex pump light. The first two-core glass pin comprises a first optical fiber, a second optical fiber, a first two-core capillary tube and a first glass tube. The second two-core glass pin comprises a third optical fiber, a fourth optical fiber, a second two-core capillary tube and a second glass tube. The first optical fiber, the second optical fiber, the third optical fiber and the fourth optical fiber are optical fibers after being processing in a beam expanding mode. The pump integrated optical device integrates the multiple functions of a wavelength division multiplexer, an isolator and a gain flatness filter.

The present invention relates to a low noise cascode amplifier comprising a first transistor, a second transistor, a third transistor, a first inductor, and a second inductor. Furthermore, the first transistor can connect with the second transistor via the first inductor, and the second transistor can connect with the third transistor via the second inductor; thereby, a cascode device can be formed. The inductor and the parasitic capacitances can resonate at high frequency, so that the noise figure of the cascode amplifier can be reduced.

A mixer of a homodyne RF receiver made from a CMOS process is provided. The mixer comprises a gain stage, a switch stage and a load stage. The gain stage receives a differential-typed RF signal and generating a first gained signal. The switch stage mixes the first gained signal and a LO signal to direct down-convert into a modulated signal. The load stage comprises a first transistor, an impedance element and a second transistor. The first transistor provides a low impedance to permit the modulated signal entering the load stage. The second transistor provides a high impedance to resist signals. The load stage converts the modulated signal to a second gained signal according to a first gain coefficient of the impedance element. The first transistor is a parallel pnp BJT, and the second transistor is a vertical npn bipolar BJT.

The invention relates to a semiconductor optic element of light amplifier, which comprises the following parts: substrate, breaker, up-envelope, active region, down-envelop, ohmic contact layer, top or bottom chip with up or down metal electrode separately, anti-reflection film plated on the input and output end face of amplifier. The reflectance of anti-reflection film output end face is less than input end face. There are N electric insulating slots, which are etched on the top of the metal electrode, which divide amplifier into N+1 annellus (each annelet has an up-electrode, N>=2) along the tune direction. The invention improves SOA noise index and saturated outcoming power.

The present invention relates to a signal converting device and receiving device in a wireless communication system. The receiving device of the wireless communication system includes a differential signal converter for receiving a single ended radio frequency signal and converting it into a differential radio frequency signal, and a frequency down converter for down converting the differential radio frequency signal to down frequency signal.

The present invention relates to optical communication. In the Er-doped fiber amplifier, the signal light provided by the tunable laser is output to the input end of the 90:10 optical coupler, the 90% output end of the 90:10 optical coupler is connected to the isolator, the other end of the isolator is connected to the 1550 port of 1550 / 980 nm wavelength selecting coupler, the 980 port is connected to 980 nm pumped laser; one end of the wavelength interleaving multiplexer, the Er-doped fiber, the isolator, the input of the wavelength interleaving multiplexer are connected successively; the wavelength interleaving multiplexer has its even number outputs connected to spectral analyzer and odd number outputs connected to the second input of the 90:10 optical coupler via a variable attenuator so as to one closed ring cavity. The amplified signal light may be output without containing laser and has low noise index, and the amplifier may be used in different WDM system.

The invention discloses a single-end input double-end output amplifier circuit and signal disposing circuit, which comprises the following parts: amplifier to amplify the input signal, input end to receive the input signal and first output end, single-end input double-end output conversion circuit to converse the amplified signal to differential signal, first transistor to receive the amplified signal, first grid to couple the first output end, first first pole to couple the second output end, first second pole to couple the first node, second transistor with second grid to couple the second first pole of third output end, second second pole to couple the first node, second capacitance coupled between the second output end and second grid, first resistance coupled between the second output end and power source, second resistance coupled between the third output end and voltage source, current source coupled between the first node and ground point.

The invention discloses a silicon-based millimeter wave receiving front-end circuit, which is applied to the field of radio frequency integrated circuits and is used for solving the problems of high power consumption, high cost and poor performance in the prior art. The silicon-based millimeter wave receiving front-end circuit comprises a cascode low-noise amplifier, a transconductance input stage, a quadrature coupling stage, a switch frequency mixing stage and an output load stage. The orthogonal coupling stage is designed at the mixer part, so that two paths of output signals at the receiving front end are equal in size, the phase difference is 90 degrees, the linearity is improved, and two paths of output are realized by using the same mixer, thereby reducing the power consumption.

A low noise amplifier having a wide operating frequency band and a high dynamic range is provided. A transformer having a secondary winding connected between an input terminal to which an input signal is applied and a positive differential output terminal, and a primary winding connected between a negative differential output terminal and an input node is provided as a feedback circuit between a cascode amplifier circuit, which includes transistors and a resistor, and an output circuit, which includes a transistor and a constant current source. Selective use of a transformer whose leakage inductance has an adequate value as the feedback transformer can realize a low noise amplifier which has a wide operating frequency band and a high dynamic range.

The invention discloses a resistance-feedback noise-cancelling broadband low-nose transconductance amplifier and belongs to the field of integrated circuits. The amplifier is in an differential input / output structure and comprises a resistance-feedback input stage, a current mirror amplifying stage, a noise-canceling auxiliary stage, and a negative resistance stage; a radio frequency signal VRF+ is input through the resistance-feedback input stage and then divides into two signals; on a main path, one signal is converted into a current signal by an input tube and is then transmitted to an output node Iout+ after being amplified by a current mirror and multiplied by a negative resistance tube; on a noise-cancelling auxiliary path, the other signal is converted by a phase inverter into signal current transmitted to an output node Iout-; the two differential current signals are of equal amplitudes but opposite directions. The amplifier has the advantages that the gain of the amplifier can be evidently increased in a broader spectral range and noise and linear performances are improved.

The invention provides a precise synchronization-unrequired coal mine underground spread spectrum accurate ranging method and a device. According to the precise synchronization-unrequired coal mine underground spread spectrum accurate ranging method, a parallel and tracking loop-free pseudo-noise code synchronization accurate measurement algorithm is adopted, such that higher time resolution can be obtained based on rough synchronization without precise synchronization process required, and therefore, ranging pseudo code speed can be decreased, and bandwidth occupied by ranging pseudo codes is limited below 100MHZ, and thus, meter-level positioning accuracy can be achieved. The device for realizing the method comprises a communication control module and a wireless response module; the communication control module, adopting a high-performance FPGA as a core processor, mainly comprises a transmitter and a receiver; and the wireless response module de-spreads received signals through adopting a search-track-free synchronization mode without a separate processor required. The precise synchronization-unrequired coal mine underground spread spectrum accurate ranging method and the device of the invention can inhibit serious electromagnetic interference under a coal mine, and are advantageous in robust hardware designs, redundant algorithms, high-accurate ranging and strong real-time property, are suitable for a coal mine underground personnel precise positioning system.

The present invention relates to a double-way backward pumped L-band erbium-doped optical fiber amplifier, and belongs to the optical communication technical field comprises a tunable laser, an optical circulator, a 980 / L-band-wavelength selecting coupler, an erbium-doped optical fiber, a pumped laser, a reflecting mirror of optical fiber ring and a optical spectrum analyzer, and are connected in the relationship that the optical circulator has three ports, one of the three ports is connected with the tunable laser, another one of the three ports is connected with one end of the erbium-doped optical fiber, the third port of the optical circulator is connected with the optical spectrum analyzer; and the other end of the erbium-doped optical fiber is connected with the public port of the 980 / L-band-wavelength selecting coupler; the 980nm port of the 980 / L-band-wavelength selecting coupler is connected with the pumped laser; the 1550 port of the 980 / L-band-wavelength selecting coupler is connected with the a reflecting mirror of optical fiber ring. The present invention can use lower pump power to achieve higher small-signal gain and low noise index.

The invention relates to a multi-mode pump laser and an optical fiber amplifier formed by the same. The multi-mode pump laser comprises a multi-mode pump laser package module (1) and an output tail fiber (2-1), wherein the output tail fiber (2-1) is a doubly clad optical fiber, the multi-mode pump laser package module (1) comprises a pump laser package shell (1-4) and a pump laser die (1-1) built in the pump laser package shell (1-4), the output tail fiber at the outer part of the pump laser package shell (1-4) is provided with an optical fiber Bragg grating (2-2), the optical fiber amplifier comprises the multi-mode pump laser and a pump signal combiner, the output tail fiber of the multi-mode pump laser is connected with the pump end of the pump signal combiner, the signal end of the pump signal combiner adopts a common single-mode optical fiber, and both the pump end and the common end of the pump signal combiner adopt a doubly clad optical fiber. Under the same pump power, the optical fiber amplifier comprising the multi-mode pump laser and the pump signal combiner disclosed by the invention has lower noise index.

The present invention relates to a method for effecting regulation of the effective noise figure of a CDMA (Code Division Multiple Access) receiver. The regulation process can be used to control the receiver during the activation / deactivation of a cell / sector in a CDMA wireless system and during normal operation when the service area of the cell / sector needs to enlarge or shrink. In a most preferred embodiment the CDMA receiver includes a source of pseudo-random noise that is injected in the received signal, downstream of the signal digitization stage. A power detector measures the power in the received digitized signal and a program logic determines the amount of noise figure degradation to be applied. The actual noise power regulation is effected by multiplying the output of the noise generator by a weighing factor. In a multi-channel CDMA system, each channel is provided with an independent system to regulate the effective noise power figure degradation, thus allowing to effect a noise figure regulation on a channel by channel basis.

At least two passive antenna arrays of an existing multicarrier base station transceiver system are supplemented by an auxiliary antenna array to provide a system and method of enhancing reverse link sensitivity and reducing the effects of multipath fading in a wireless communication system without the need for modifications to the mobile station. The auxiliary antenna array provides a complementary transmit diversity path for the two passive antennas such that a predetermined time delay is implemented to a composite transmit signal and the delayed composite transmit signal is fed directly to the auxiliary antenna array. The delayed signal and the signals from the passive antenna arrays provide a reduced noise figure and time delay transmit diversity for the multicarrier BTS operation.