237 results about "Fixed gain" patented technology

Apparatus for boosting the signal between a cell phone (14) and a cell site (16), which includes an amplifier (64) that continually operates at a fixed gain. A power detector (72) controls an attenuator (62) that can be switched to pass the amplified signal through an attenuator (74) of moderate resistance, or through an attenuator (60) of zero resistance so the power output is boosted within the limits allowed under cell phone system standards.

A temperature to digital converter device is implemented by integrating a temperature sensor circuit into an analog-to-digital converter (ADC). Temperature-to-digital conversion is accomplished by first measuring a change in voltage (ΔVBE) across the junction of a diode when different current densities are forced through the junction. The thus obtained ΔVBE is proportional to temperature. As part of the conversion processing, ΔVBE is multiplied by a fixed gain, and an offset voltage value is subtracted from ΔVBE. The multiplication and subtraction functions are performed by a switched-capacitor integrator in a delta-sigma ADC and the ADC itself operates as the temperature-to-digital converter device, eliminating the extra amplifier and / or capacitors required when the multiplication and / or subtraction function are performed outside the ADC. Alternately, other ADC topologies that include an integrator or gain amplifier, such as pipeline ADCs and cyclic ADCs may be used in place of the delta-sigma ADC.

The invention discloses an analog / digital configurable variable-gain amplifier, which comprises a variable-gain amplifier module VGA and an analog / digital configurable control circuit. The variable-gain amplifier module is formed by a plurality of variable-gain amplifiers and a fixed-gain amplifier in concatenation connection. The analog / digital configurable control circuit comprises an analog mode control circuit and a digital mode control circuit. A comparator and a charge pump of the analog mode control circuit detect the size of amplitude of an output signal, output an appropriate control voltage and feed back the control voltage to the VGA so as to regulate the gain of the VGA. The digital mode control circuit controls an internal switch circuit by means of an external signal, generates the control voltage by means of a decoder and an I-V converter according to an input signal provided by a digital baseband processing module chip and feeds back the control voltage to the VGA so as to change the gain of the VGA. The analog / digital configurable variable-gain amplifier can flexibly switch between an analog mode and a digital mode and is especially suitable for a radio-frequency front end circuit for different baseband chips.

A dual microphone communication device comprising a first microphone module, a second microphone module and a mixer circuit is provided. The first microphone module amplifies a near-end audio signal to produce a first audio signal. The second microphone module receives and amplifies the near-end audio signal by a fixed gain and a constant phase difference to produce a second audio signal. The mixer circuit subtracts the second audio signal from the first audio signal to produce a third audio signal so that interference resulting from echoes is significantly reduced while keeping, or enhance the near end voice level.

A control circuit comprises a circuit adapted to determine a state of charge of a high side power source using a sensed output current to provide a variable gain signal based on the state of charge. The control circuit may also contain a circuit configured to provide a fixed gain signal based on the current of the high side power source and a circuit configured to combine the variable gain signal and the fixed gain signal to create a power command.

A wireless local area network receiver having separate automatic gain control (AGC) loops for providing a radio frequency AGC and a baseband frequency AGC, as well as a DC offset cancellation circuit. The AGC loops control a low noise amplifier amplifying the received RF signal, and the baseband signal or signals from a mixer of I and Q mixers. The DC offset compensation loop is also responsive to the baseband AGC signal to maintain a substantially fixed gain in the DC offset compensation feedback. Details of various embodiments are disclosed, including embodiments for orthogonal frequency division multiplexing (OFDM) that provide the AGC operation and the DC offset cancellation to the desired levels within the relatively short period of a preamble that precedes the data transmission.

A method for calibrating a fixed gain amplifier configured as a front-end amplification stage of an analog-to-digital converter including sampling a calibration voltage with normal and inversed polarity and with the fixed gain amplifier bypassed and with the fixed gain amplifier connected. An actual gain value of the fixed gain amplifier is computed from offset corrected digital output codes generated from converting the calibration voltage. A gain correction value for the fixed gain amplifier can then be computed based on the ratio of the actual gain to the ideal gain. In another embodiment, a method for calibrating an analog-to-digital converter including a fixed gain amplifier, an input buffer and a modulator generates an offset correction value using normal and polarity inversed input samples. The offset correct value provides correction for at least offset errors in the fixed gain amplifier, the input buffer and the modulator.

An optical disc drive system is employed in conjunction with a storage medium having a plurality of data sectors each provided with a header and a data storage area. The system includes a data detection device for retrieving stored data from the storage medium and outputting a data signal, an amplifier for providing a variable gain to the data signal and outputting an amplified data signal, a detector that is responsive to the amplified data signal for evaluating a predetermined one of the sectors to ascertain whether the storage area is blank, and an automatic gain control circuit producing a gain control output for controlling the gain of the amplifier. The control circuit has a first mode and a second mode, the first mode being active during retrieval of the header and the second mode being active during retrieval of the data storage area. The system is further provided with a sampling device for sampling the gain control output during retrieval of the stored data in a respective one of the storage areas containing previously stored data. The sampling device outputs results of the sampling, and a fixed gain control circuit is responsive to the results of the sampling for outputting a fixed gain control signal. The fixed gain control signal is applied to the amplifier during evaluation of the predetermined one of the sectors.

The invention relates to a method and a device for eliminating exercise electrocardiosignal interference. The method includes the following steps: collecting exercise electrocardiosignals and exercise reference signals; carrying out amplification and lowpass filtering on fixed gain of collected exercise electrocardiosignals; carrying out analog-digital conversion on amplified and lowpass filtered exercise electrocardiosignals and obtaining digital exercise electrocardiosignals; judging exercise interference degree of the digital exercise electrocardiosignals, and obtaining the exercise interference degree; carrying out self-adaptive elimination on the exercise electrocardiosignals and the exercise reference signals according to the exercise interference degree, and obtaining the exercise electrocardiosignals without interference. According to the method and the device, even when the exercise interference degree is very high, good exercise electrocardiosignals can still be obtained through offset of the exercise electrocardiosignals and the exercise reference signals, and accuracy and stability of eliminating exercise electrocardiosignal interference are improved.

The invention discloses a fixed-gain self-excited non-contact resonant converter and a control method thereof, belonging to the field of electric energy conversion. The fixed-gain self-excited non-contact resonant converter comprises a self-excited non-contact resonant converter main circuit, a secondary side current detection circuit and a driving signal generation circuit. Detected current is set according to the compensation method of a resonant converter: for series / series and parallel / series compensation circuits, the secondary side current of a non-contact transformer is detected, and for series / parallel compensation circuits, the input current of a secondary side rectifier bridge is detected. The detected current is detected by the secondary side current detection circuit, a detection signal is isolated and fed back to a primary side through the driving signal generation circuit, and phase compensation is conducted to accurately detect the phase information of the secondary side detected current. According to a found characteristic that the phase of the secondary side detected current at the fixed gain position of the non-contact resonant converter is the same as the phase of square wave signals at the middle point of an inverter bridge arm in the main circuit (1), the detected secondary side current signals are converted into the driving signals of the main circuit to realize self-excitation control. On one hand, a real-time response can be made to the parameter change of the non-contact transformer; and on the other hand, the output of the non-contact resonant converter can be ensured to be stable when a load is changed.

A temperature to digital converter device is implemented by integrating a temperature sensor circuit into an analog-to-digital converter (ADC). Temperature-to-digital conversion is accomplished by first measuring a change in voltage (ΔVBE) across the junction of a diode when different current densities are forced through the junction. The thus obtained ΔVBE is proportional to temperature. As part of the conversion processing, ΔVBE is multiplied by a fixed gain, and an offset voltage value is subtracted from ΔVBE. The multiplication and subtraction functions are performed by a switched-capacitor integrator in a delta-sigma ADC and the ADC itself operates as the temperature-to-digital converter device, eliminating the extra amplifier and / or capacitors required when the multiplication and / or subtraction function are performed outside the ADC. Alternately, other ADC topologies that include an integrator or gain amplifier, such as pipeline ADCs and cyclic ADCs may be used in place of the delta-sigma ADC.

A variable gain amplifier of low amplitude distortion, and low noise, having a large variable range, is provided. A variable gain differential amplifier that controls a gain by use of bias current is used as each of unit amplifiers (VGAs) making up the variable gain amplifier. A large variable gain range is obtained by series-connecting a plurality of the variable gain differential amplifiers. An attenuator is installed on the input side of the unit amplifier (VGA) at least in the initial stage. By doing so, it becomes possible to prevent amplitude distortion from occurring to the respective VGAs. An attenuator utilizing voltage division by capacitors, generating no noise, is used for lowering noise. Further, the variable gain amplifier is provided with a fixed gain amplifier installed in the final stage as necessary in order to obtain a total gain as desired. With the use of the variable gain amplifier as a variable gain amplifier for output power control of a polar loop transmitter, an excellent function for output power control can be achieved without causing significant deterioration in distortion characteristic and noise characteristic thereof.

A method and system for adapting low noise amplifier gain comprise determining a Bluetooth received signal strength indication of Bluetooth signals transmitted by a Bluetooth peer; determining a WLAN received signal strength indication of WLAN signals transmitted by a WLAN peer; comparing the Bluetooth received signal strength indication to a predetermined Bluetooth signal strength threshold to determine a Bluetooth peer distance of the Bluetooth peer; comparing the WLAN received signal strength indication to a predetermined WLAN signal strength threshold to determine a WLAN peer distance of the WLAN peer; and controlling a gain of a low noise amplifier to be applied to the Bluetooth signals and the WLAN signals based on the Bluetooth peer distance and the WLAN peer distance. In a further embodiment, the gain may be controlled by using a bypass signal to place the low noise amplifier into at least one of (a) a bypass mode in which the Bluetooth signals and the WLAN signals pass through the low noise amplifier without the gain being applied, and (b) a fixed gain mode in which the gain is applied to the Bluetooth signals and the WLAN signals. In another embodiment, the gain may be controlled by using the bypass signal to control an internal WLAN low noise amplifier and an internal Bluetooth low noise amplifier.

The invention provides a communication link used for a telemetry and telecontrol communication system. An uplink broadcasing and downlink TDMA (time division multiple access) mode is adopted to solve the measurement and control problems of a single ground station for multiple aircrafts. A downlink adopts hybrid spread spectrum BPSK (binary phase shift keying) with multiple stages of adjustable gain for modulation, an uplink adopts coded spread spectrum QPSK (quadrature phase shift keying) with fixed gain for modulation, so that the anti-interference, anti-interception and anti-capturing capacity of a wireless link is improved, and asymmetry of the uplink and the downlink is considered. Both the uplink and the downlink adopt a single-pulse modulation symbol packet transmission mode, a fixed interval is inserted into every two adjacent symbol pulses, and accordingly, the spread spectrum signal capturing, tracking and synchronizing complication of receivers is reduced. Non-coherent demodulation is adopted, a complicated carrier synchronization problem is avoided, and the design and project realization of the receivers are further simplified. The complicated carrier synchronization problem is avoided, and wireless communication between a single ground station device and multiple telecontrol terminal devices is realized.

A variable gain amplifier (VGA) circuit and an automatic gain control (AGC) method thereof are disclosed. The VGA circuit includes an amplifier circuit and an AGC circuit. The amplifier circuit amplifies an input signal to an output signal according to a predetermined gain and the AGC circuit is connected to the amplifier circuit for regulating the predetermined gain. The AGC circuit further includes a peak detector detecting a peak of the output signal, a replica of the peak detector for detecting a peak of a reference signal, and a comparator for comparing the peak of the output signal with the peak of the reference signal to provide a control signal and then providing the control signal to the amplifier circuit to regulate the predetermined gain.

Light signals of first to n-th bands amplified en bloc undergo proper attenuation through an adjustable optical attenuator in conformance with attenuation in an optical fiber connected to input of an optical amplifying repeater apparatus, whereon the light signals are demultiplexed or separated into individual bands and amplified by first to n-th fixed-gain optical amplifiers (#1, . . . , #n) each having a high fixed gain in the respective bands to be subsequently multiplexed by an optical multiplexer and then sent out onto a transmission line. A monitoring light branching device extracts a part of light power of a specific monitoring wavelength, which is then fed to an adjustable attenuator control circuit which controls the attenuation factor of the adjustable optical attenuator so that the light power of the specific wavelength remains constant. The gain of the optical amplifying repeater apparatus at the specific wavelength can thus be determined. By employing as the optical amplifying medium a substantially homogeneous medium, the gain for the other wavelengths can be fixed. The optical amplifying repeater apparatus whose gain is essentially independent of the change in the number of the wavelengths can thus be realized.

The invention discloses a radio-frequency emission front-end circuit with automatic gain control, which comprises a radio-frequency variable gain power amplifier, a radio-frequency variable gain modulator and a radio-frequency amplitude detection automatic control circuit, wherein the radio-frequency variable gain power amplifier is composed of a first-level variable gain amplifier and a fixed gain power amplifier which are in cascade connection; the radio-frequency amplitude detection automatic control circuit comprises a radio-frequency amplitude detection circuit and a feedback control digital circuit; and the radio-frequency amplitude detection automatic control circuit is used for detecting the amplitude magnitude of a first-level output signal in a radio-frequency variable gain power amplifier circuit and controlling the magnitude of the gain of a radio-frequency variable gain modulator circuit and a radio-frequency variable gain power amplifier circuit according to amplitude magnitude feedback. The radio-frequency emission front-end circuit provided by the invention has the advantages of being flexibly applied to an amplitude keying emission circuit, especially being suitable for the occasion with relative sensitivity to emission signal power and demand on emission power being free from changing along with the change of temperature and technique.

The invention discloses a calibration method of a time division-synchronization code division multiple access (TD-SCDMA) terminal, which increases terminal calibration speed and enhances terminal calibration accuracy. The technical scheme comprises three aspects, namely automatic frequency control calibration, automatic gain control calibration and automatic power control calibration, wherein the automatic frequency control calibration comprises the following steps of: under the fixed input signal power of a signal source, changing a control word; demodulating to acquire data of a plurality of frames; calculating frequency information; and performing linear variation to acquire a step change value and an automatic frequency control initial value; the automatic gain control calibration comprise the following steps of: under the fixed input signal power of the signal source, changing the control word to acquire a plurality of groups of receiving signal intensity values, a gain value of a fixed gain module and a gain slope of a variable gain module; calculating input signal power and a gain value and combining automatic gain calibration tables; and the automatic power control calibration comprises the following steps of: transmitting a power list by gradually increasing or decreasing control words at a fixed periodic interval by using the terminal; acquiring data by using a frequency spectrograph; and selecting a power value and a control word.

The invention provides an angular velocity estimation based self-adaptive fuzzy sliding mode control method, applies the self-adaptive fuzzy sliding mode control method to a micro three-axis gyroscope control system, and can realize the trajectory tracking control and parameter estimation of a micro gyroscope system. According to the self-adaptive fuzzy sliding mode control method, a controller is designed on the basis the state-space equation of a micro gyroscope. Firstly, on the basis of the sliding mode controller, a novel self-adaptive identification method is designed, and the angular velocity of the micro gyroscope and the estimated valves of other systematic parameters are updated on line and in real time; besides, a fixed gain in a sliding mode control toggle item is adjusted by virtue of a self-adaptive fuzzy system, and fuzzy approximation is performed to the upper bound of the fixed gain, so that a chattering phenomenon arising in sliding mode control can be reduced. Through the adoption of the self-adaptive fuzzy sliding mode control method, a favorable tracking performance can be obtained, and the self-adaptive fuzzy sliding mode control method has robustness in parameter variation and external disturbance.

The invention discloses an RRU adaptive power adjustment method and a device thereof to solve the problem of how to adaptively adjust sending signal power by RRU such that the measurement of DPD / RPD / OPD is accurate when the power of transmission signal between a BBU and an RRU is fixed. The method comprises the following steps: the RRU periodically receiving the signal and first power control information transmitted by the BBU, and whether a power measurement task exists or not currently is detected; if the power measurement task does not exist, the power adjustment of the signal received from the BBU is carried out according to the first power control information; if the power measurement task exists, programmable gain control PGC related parameter is set as a default value, the current power measurement is executed continuously until the measurement of current power is completed, thus when the fixed gain between the BBU and the RRU is sent, through the control of PGC, the processing of the DPD / OPD / RPD is not affected by gain change, and the measurement of the DPD / OPD / RPD is accurately completed.

The invention provides a signal amplifying stage, used in a signal receiver. The signal amplifying stage has: a fixed-gain low noise amplifier (LNA), amplifying an input signal; a variable-gain LNA (VG-LNA) array, amplifying the input signal, including a plurality of parallel VG-LNAs, the VG-LNA array being parallel with the fixed-gain LNA; a variable-gain amplifier (VGA), being in series with the fixed-gain LNA and the VG-LNA array, for amplifying output signals from the fixed-gain LNA and the VG-LNA array to generate an output signal; an attenuator, being in parallel with a combination of the fixed-gain LNA, the VG-LNA array and the VGA, for attenuating the input signal to generate the output signal; and a control loop, coupled to the VGA and the attenuator, for detecting power levels of the output signal to enable and control the fixed-gain LNA, the VG-LNA array, the VGA and the attenuator.

The invention discloses a signal processing circuit of a linear Hall sensor, which comprises an over-sampling loop and two chopping modulators. The over-sampling loop consists of a CPA (chopping amplifier), a first order loop wave filter, a four-bit digital converter and a feedback circuit, wherein the first order loop filter contains a filter capacitor and an integrating amplifier (ITA). The two chopping modulators are respectively embedded in front of and behind the CPA. The CPA is an operational transconductance amplifier which linearly converts an outputted voltage signal into current and keeps fixed gain under the full conditions. The filter capacitor and the ITA are connected with an active first order wave filter of the over-sampling loop. The four-bit digital converter converts a filtered signal into a four-bit digital signal; and the feedback formed by a four-bit DAC (Digital-to-Analog Converter) and a Hall dish converts an output code into feedback voltage; and the feedback voltage is subtracted from an inputted signal. As the inputted signal is very weak, the offset voltage of the CPA and the flicker noise are modulated by the chopping modulators in front of and behind the CPA into a high-frequency band and are filtered by a wave filter. The constant Gm in the CPA keeps the loop more stable under the full conditions.

The invention discloses a beam former based on a field programmable gate array (FPGA) and a sparse energy converter planar array, comprising a sparse energy converter planar array, an analog adjusting circuit, an analog-to-digital conversion chip and an FPGA chip, wherein the sparse energy converter planar array is used for converting a seabed sonar echo signal into a weak electric signal; the analog adjusting circuit is used for carrying out the signal adjustment of fixed gain magnification, time varying gain control, bandpass filtration and the like on the weak electric signal; and the analog-to-digital conversion chip is used for synchronously sampling the analog electric signal after signal adjustment and converting the analog electric signal into a digital signal; and the FPGA chip carries out beam forming calculation, carries out L point discrete Fourier transform on all sampling passages of the analog-to-digital conversion chip to obtain S<m, n>(1) and carries out multiplication accumulation operation on the discrete Fourier transform result S<m, n>(1). The invention can be applied to a phased array three-dimensional sonar image system with high resolution ratio, optimizes a beam forming algorithm and greatly reduces the multiplication accumulation calculation needed by a system and the system cost.

The invention discloses a radio frequency amplitude keying demodulation circuit with large input dynamic range, which comprises an amplitude detection circuit, a Gaussian filter circuit, a peak detection circuit and two branches of difference amplitude keying demodulation circuits of a comparison circuit. The amplitude detection circuit is formed by a fixed gain amplifier with S poles in series connection and an amplitude detection and conversion circuit. Each branch of the amplitude keying demodulation circuits includes that input signals are amplified to i fuzzy amplitude keying signals through the amplitude detection circuit, the i fuzzy amplitude keying signals are added and converted into high-low voltage amplitude signals, high frequency components are filtered through the Gaussian filter circuit, the filtered signals pass through the peak detection circuit to obtain high-low average amplitude signals, and the average amplitude signals and the signals filtered by the Gaussian filter circuit are compared through the comparison circuit to obtain demodulation signals output by the radio frequency amplitude keying demodulation circuit. The radio frequency amplitude keying demodulation circuit with the large input dynamic range can be flexibly used for demodulating amplitude detection signals with modulation degree ranging from 0.5 to 0.9, thereby being capable of being applied to the front end of a radio frequency receiver with input signals reaching up to 60dB dynamic range.

A control circuit comprises a circuit adapted to determine a state of charge of a high side power source using a sensed output current to provide a variable gain signal based on the state of charge. The control circuit may also contain a circuit configured to provide a fixed gain signal based on the current of the high side power source and a circuit configured to combine the variable gain signal and the fixed gain signal to create a power command.

A variable gain control amplifier (10) and method provides a substantially constant input impedance and output impedance, and provides a substantially constant noise figure and third order harmonic. The variable gain control amplifier (10) includes an amplifier stage including at least a first intermediate fixed gain stage (22) operative to produce a first intermediate signal (30) in response to the input signal (20). The variable gain control amplifier (10) further includes at least a second intermediate fixed gain stage (24) operative to produce an output signal (18) in response to the first intermediate signal (30). A feedback circuit (16) is operative to produce a gain control signal (32) in response to the output signal (18). A gain control circuit (26) is coupled to the at least first intermediate fixed gain stage (22) and the second intermediate fixed gain stage (24), and receives the gain control signal (32) to control an amplitude of the intermediate signal (30).

A system includes an angular rate sensor disposed in a vehicle for providing angular rates of the vehicle, and an instrument disposed in the vehicle for providing line-of-sight control with respect to a line-of-sight reference. The instrument includes an integrator which is configured to integrate the angular rates of the vehicle to form non-compensated attitudes. Also included is a compensator coupled across the integrator, in a feed-forward loop, for receiving the angular rates of the vehicle and outputting compensated angular rates of the vehicle. A summer combines the non-compensated attitudes and the compensated angular rates of the to vehicle to form estimated vehicle attitudes for controlling the instrument with respect to the line-of-sight reference. The compensator is configured to provide error compensation to the instrument free-of any feedback loop that uses an error signal. The compensator may include a transfer function providing a fixed gain to the received angular rates of the vehicle. The compensator may, alternatively, include a is transfer function providing a variable gain as a function of frequency to operate on the received angular rates of the vehicle.

The invention discloses an information processing method and system and an electronic device. The defects of speech amplitude truncation and reduced speech recognition rate, which are caused by the fact that fixed gain is carried out on a speech signal with high volume at the present, are overcome. The method is applied to the electronic device. The electronic device has a speech acquisition unit. The method comprises the steps that the speech signal is acquired through the speech acquisition unit; the speech signal is analyzed to acquire the environmental noise of the environment of the electronic device; based on the corresponding relationship among the environment noise, the preset level of the environment noise and a speech signal processing method, the speech signal processing method corresponding to the environment noise is determined; and first processing is carried out on the speech signal based on the speech signal processing method corresponding to the environment noise, so that the amplitude of the speech signal is maintained in a predetermined range. According to the embodiment of the invention, the signal-to-noise ratio can be maximized, and the speech accuracy and recognition rate are improved.