116 results about "Carrier leakage" patented technology

The invention provides a method for precisely estimating a large frequency offset of a DFT-s-OFDM (Direct Fourier Transformer Spread Orthogonal Frequency Division Multiplexing) system. The method comprises the following steps of synchronizing SC-OFMA (Single-Carrier Orthogonal Frequency Division Multiplexing) symbols; performing frequency offset estimation by utilization of a synchronized cyclic prefix CP and a data section tail part Tail so as to obtain a small frequency offset, and compensating the small frequency offset on a receiving signal; performing automatic RB (Resource Block) detection after removing the carrier leakage from the compensated receiving signal, and distributing sub carriers according to frequency domain RB so as to obtain a large frequency offset; generating a DMRS (Demodulation Reference Signal) local reference signal for a time slot under an unknown time slot number according to receiver DMRS symbols; obtaining a precise frequency offset according to an average phase difference of two DMRS symbols in one sub carrier, and obtaining a large frequency offset estimation range. According to the method for precisely estimating the large frequency offset of the DFT-s-OFDM system, the inter-symbol interference and the inter-sub carrier interference can be conquered, and the frequency offset estimation on signals is realized under the condition of unnecessarily knowing signal resource block allocation and sub frame sequence number in advance, so that the frequency offset range is enlarged, and the precision of the estimation result is improved.

A method and apparatus that provide a frequency conversion in a radio frequency front-end are disclosed, including a frequency divider that divides an input signal frequency by a predetermined value to produce an output signal frequency; and a frequency mixer that mixes the output signal frequency with a carrier signal frequency to produce a converted signal frequency, which is substantially equal to a difference between the output signal frequency and the carrier signal frequency. The predetermined value and the input signal frequency are selected such that the carrier signal frequency is not substantially equivalent to an integer multiple of the output signal frequency. The method and apparatus can be used in a wireless communication receiver including wireless communication systems and wireless LAN systems.

The method includes following steps: (1) DC offset correction for the receiving channel to obtain value of residual error; (2) switching on the transmitting channel and the receiving channel, and obtaining configured gain reasonably; (3) carrying out calibration for carrier wave leakage (CWL) power to calculate out compensation value; (4) turning off the receiving channel, and in transmission procedure, compensation value are carried in sub circuits in the transmitting channel in order to complete CWL and compensation. The invention also discloses device for restraining CWL. Structure of the device includes at least digital baseband, chip of transceiver, front end, and antenna. Without need of additional directional coupler and power detection apparatus, the invention through the receiving channel detects CWL power existed in the transmitting channel. The invention does not need multiple iterations to solve and search optimal value. The compensation algorithm is high performance.

An exemplary apparatus includes a modulator configured to modulate a data signal onto a carrier signal to generate a modulated signal having a transmit frequency within a predefined frequency range adjacent to and within a boundary of an uplink frequency band, a filter configured to at least partially remove a carrier frequency component from the modulated signal to produce a filtered modulated signal, and an antenna configured to transmit the filtered modulated signal.

The invention provides a WLAN transceiver with the carrier leakage correction and compensation functions. An ADC for collecting data or a DAC for carrier leakage compensation and I/Q mismatch compensation does not need to be introduced into a radio frequency part of the WLAN transceiver, only a simple correction path needs to the designed, the correction and compensation are achieved through a digital base band, and very high precision can be achieved only by carrying out a few iterations.

The number of measurements needed to calibrate an electrical device is reduced. Apparatus and methods minimize output of one or more unwanted signals by determining a calibration setting, in a minimal number of measurements, from determined distances to a best setting. Each distance to a best setting can be determined as a function of the characteristic of the unwanted signal and the measured unwanted signal level. A calibration setting point can be determined by searching for a setting point having a lowest sum of distance errors determined from the calculated distances and from the measured and non measured setting points. The techniques and apparatus are useful for minimizing a number of measurements that would be needed for determining a setting that substantially prevents generation of unwanted output signals, such as carrier leakage (LO-leakage) and unwanted sidebands, and for quickly determining whether an acceptable calibration setting exists for a device.

A mobile communication terminal has a radio frequency identification (RFID) system to read information from RFID tags at predetermined distances. An RFID transmission antenna to transmit or receive a wireless signal for mobile communication to/from a base station, or transmit wireless signal to the RFID tag, and an RFID reception antenna to receive RFID wireless signal transmitted from the RFID tag. Accordingly, ingress of the RFID transmission carrier leakage to the RFID reception circuit can be prevented. Additionally, a small size antenna such as a chip ceramic antenna is used exclusively for RFID reception, and the RFID reception antenna is also used as a mobile communication antenna. As a result, the mobile communication terminal can be compact-sized, the size of transmission signal can be increased, and dynamic range increases without having to increase the sensitivity of the RFID tag, to extend the communication distance.

The invention relates to a transmitter gain distribution method and circuit. The method comprises the following steps: respectively setting a gain of an intermediate frequency module and a gain of a radio frequency module according to the output power of a transmitter and through combining a preset condition, wherein the preset condition is the corresponding relation among the output power, the gain of the intermediate frequency module and the gain of the radio frequency module; stepping the gain of the intermediate frequency module according to the step length of 1 dB, and circulating in the stepping range of 6 dB in sequence; stepping the gain of the radio frequency module according to the step length of 6 dB, wherein the stepping range is the dynamic range of the output power, and the value of the any gain of the radio frequency module corresponds to the values of six types of continuous output power, and corresponds to a circulation of the gain of the intermediate frequency module. According to the method and the circuit, the carrier leakage suppression can be optimized in the dynamic range of the overall output power effectively, and moreover, the power consumption is reduced along with the reduction of the output power, so that the efficiency is improved.

The invention provides a digital correction method for IQ channel mismatch of a novel broadband receiver. The digital correction method for the IQ channel mismatch is proposed by fully utilizing the magnitude-frequency characteristic of an IQ digital signal on the basis of narrowband signal correction. An orthogonal error exists in zero intermediate frequency modulation, and a generated residual mirror image and a carrier leakage signal can generate in-band interference, thus reducing the signal-to-noise ratio of a modulation signal and scattering constellation points. The IQ correction closed loop method that has non-ideal characteristics and is easy to implement provided by the invention provides a basic method and a specific operation. The method has the advantages of simple algorithm, little hardware resource occupation, strong portability, simple and convenient subsequent maintenance and so on. By adopting the method, the mirror image and the power of the carrier leakage of the signal on the frequency spectrum can be reduced, the amplitude-phase error within the entire working bandwidth is effectively corrected, the dynamic range of a wireless communication device is expanded, the requirements of a broadband wireless communication system are satisfied, and the signal-to-noise ratio of the modulation signal is increased.

An embodiment of a mixer with carrier leakage self-calibrating is disclosed. The mixer comprises a double balanced mixer, a gm stage comprising a first processing unit and a second processing unit, a current duplicating circuit, a capacitor, a controller and a current compensation unit. The current duplicating circuit selects the first processing unit or the second processing unit and duplicates a duplicated current of the selected processing unit to charge the capacitor. The capacitor has a first terminal and a second terminal, wherein the second terminal is grounded and the first terminal receives the duplicated current. The controller determines a charge time of the capacitor to generate a compensation signal, wherein the charge time is the time that the voltage of the capacitor is charged to equal to a reference voltage. The current compensation unit receives the compensation signal to generate a compensation current to the mixer.

According to one embodiment of the invention, a system for controlling carrier leakage in a communications device is provided. The system includes a first mixer unit operable to receive a first signal, to convert the first signal into a second signal having a higher frequency than the first signal, and to transmit the second signal. The system also includes a second mixer unit. The second mixer unit is operable to receive the second signal, to convert the second signal into an in-phase signal and a quadrature signal each having lower frequency than the second signal, and to transmit the in-phase signal and the quadrature signal. The system also includes a processor coupled to the first mixer and the second mixer. The processor is operable to perform a leakage reduction procedure by receiving the in-phase signal and the quadrature signal from the second mixer, sampling the in-phase signal and the quadrature signal, determining that a result from the sampling is not equal to a predetermined value, initiating a transmission of a direct current offset signal to the first mixer unit, and adjusting a voltage of the direct current offset signal until a next result of the sampling approximately equals the predetermined value.

The invention discloses a system for suppressing carrier leakage, and the system comprises a directional coupler, a quadrature demodulator and a reflection signal module, wherein the directional coupler is used for outputting leaked radio frequency carrier signals from an isolation port to the quadrature demodulator; the quadrature demodulator is used for demodulating out in-phase and quadrature signals from the leaked radio frequency carrier signals, sending the in-phase and quadrature signals to the reflection signal module and utilizing reflection signals reflected from the reflection signal module to suppress the leaked radio frequency carrier signals; and the reflection signal module is used for performing filtration, phase rotation gain control and in-phase and out-of-phase integration on the in-phase and quadrature signals to obtain control signals of the reflection signals, utilizing the control signals to control the reflection signals and sending the reflection signals to the quadrature demodulator. The invention further discloses a method for suppressing the carrier leakage; by adopting the system and the method, leakage of forward radio frequency carrier signals can be simply and effectively suppressed.

The invention relates to a digital multi-function disc used large power 650nm semiconductor laser, which comprises a substrate used to do laser material structure external growth, a buffer layer on the substrate, a N type cladding on the buffer layer to limit the leakage of the loading unit, an active region layer on the cladding, a first P type cladding on the active region layer to limit the leakage of the loading unit, a current barrier layer on the P type cladding to barriers the current spread to reduce the current leakage, a second P type cladding on the current barrier layer and the first P type cladding to limit the leakage of the loading unit, a basaltic layer on the second P type cladding, an electrode touching layer on the basaltic layer, a double groove structure on the electrode touching layer, the basaltic layer and the second P type cladding which adopts etching bath to etch the three grooves, and a silicon nitride oxide layer on the electrode touching layer which covers the double grooves.

The invention belongs to the technical field of wireless communication and relates to a radio frequency nonideal characteristic correction method for a transmitter. The invention provides the method for correcting I/Q imbalance, carrier leakage and in-band distortion of the transmitter. A system model is processed; an inverse filter required by pre-distortion is directly calculated through utilization of an adaptive algorithm; and extra operation of estimating branch influences and then calculating the inverse filter is avoided. The invention also provides a high-efficiency tracking algorithm. Parameters of a predistorter are continuously updated online in an adaptive mode. The complexity is reduced.

The present invention provides a transmitter structure for a pulse ultra-broadband signal, including a narrow pulse generating module, a balance modulation module, a local oscillation module, an amplifier and an antenna. The balance modulation module has a symmetrical structure for implementing a two phase PSK balance modulation to a narrow pulse ultra-broadband signal, which not only reduce the effect of a dithering effectively and eliminate a positive and a negative polarity requirement generated by the narrow pulse, also can restrain a carrier leakage.

The embodiment of the invention discloses a power amplifier and a signal processing method, and relates to the field of mobile communication. The power amplifier comprises a pulse modulator, a level adjustor and an amplitude power amplifier. The embodiment of the invention also provides a signal processing method. The method is that: signals processed by at least one integrator and the signals subjected to quantitative processing in the pulse modulator are the signals obtained by respectively subtracting a level adjusting value from preset high and low level values in the pulse modulator; because the level adjusting value is obtained by dividing a saturation level value of the amplitude power amplifier by a level amplification factor, a saturation level generated by the amplitude power amplifier is generated; a carrier leakage phenomenon caused by the saturation level of the amplitude power amplifier in the conventional power amplifier used for transmitting radio-frequency signals is avoided; therefore, linear indexes such as an adjacent channel power ratio (ACPR) of the power amplifier are greatly improved; and the distortion of the signals is reduced.

High power 808nm semiconductor laser is widely applied to pumping Nd:YAG solid laser, laser processing, laser medical treatment and other fields, due to the fact that the semi-conductor laser has the advantages of high efficiency, compact structure, convenient modulation and the like. Meanwhile, people always concern the problems of the semi-conductor laser on efficiency, temperature property and the like. The invention provides design and extension growth of a 808nm laser material by adopting (In)GaAs/GaAs straining isolated layer. Adopting insertion of strained quantum barrier into a wave guide layer and an active layer as a method for improving the physical distance between a quantum well and a growth interface of an initial barrier layer and the electron reflecting layer, and reducing accumulation of heterojunction interface oxygen of an active region and a wave guide region; multiple effective methods and special wave guide structure designs are utilized in the extension growth to improve conduction band edge potential energy, enhance capability of preventing current carrier leakage, restrict current density of threshold, and improve temperature property and quantum efficiency of the laser.