Gain Control Patents (Class 455/232.1)
  • Publication number: 20040087292
    Abstract: Techniques for improved low latency frequency switching are disclosed. In one embodiment, a controller receives a frequency switch command and generates a frequency switch signal at a time determined in accordance with a system timer. In another embodiment, gain calibration is initiated subsequent to the frequency switch signal delayed by the expected frequency synthesizer settling time. In yet another embodiment, DC cancellation control and gain control are iterated to perform gain calibration, with signaling to control the iterations without need for processor intervention. Various other embodiments are also presented. Aspects of the embodiments disclosed may yield the benefit of reducing latency during frequency switching, allowing for increased measurements at alternate frequencies, reduced time spent on alternate frequencies, and the capacity and throughput improvements that follow from minimization of disruption of an active communication session and improved neighbor selection.
    Type: Application
    Filed: April 24, 2003
    Publication date: May 6, 2004
    Inventors: Da-shan Shiu, Li Zhang, Eugene Sy
  • Publication number: 20040082305
    Abstract: Systems and methods are described for a sideband suppression technique for quadrature modulation using magnitude measurements. Gain imbalance, phase imbalance, or both gain and phase imbalance are corrected in a quadrature modulator. Predetermined voltage levels are applied to one or both of the quadrature modulator input channels and resultant output magnitudes are measured. Then, a gain correction factor, a phase correction factor or both gain and a phase correction factors are determined as a function of the measured output magnitudes. Gain imbalance, phase imbalance or both gain and imbalance are then corrected using the gain and phase correction factors.
    Type: Application
    Filed: October 25, 2002
    Publication date: April 29, 2004
    Inventors: Mark A. Kirschenmann, Sumit A. Talwalkar
  • Patent number: 6728524
    Abstract: An automatic gain control circuit includes a power calculator for calculating power of a modulation wave supplied to a demodulator; a power comparator for comparing the power calculated by the power calculator with ideal power of a modulation scheme of the modulation signal; a first gain controller for carrying out gain control of a first AGC amplifier in response to an output of the power comparator; and a second gain controller for carrying out gain control of the second AGC amplifier in response to the output of the power comparator. The automatic gain control circuit can solve a problem of a conventional AGC circuit in that precision gain distribution cannot be achieved to the two AGC amplifiers because the two AGC amplifiers are controlled by a single control signal output from the automatic gain control circuit.
    Type: Grant
    Filed: December 19, 2000
    Date of Patent: April 27, 2004
    Assignee: Renesas Technology Corp.
    Inventors: Kazuya Yamanaka, Syuji Murakami
  • Patent number: 6727771
    Abstract: A semiconductor integrated circuit device includes an orthogonal modulator that maintains carrier leak characteristics regardless of attenuation of an output signal level. The orthogonal modulator includes a phase shifter circuit and generates a modulation signal. An auto gain controller amplifies the modulation signal to generate an amplified modulation signal. A gain adjusting circuit adjusts a gain of the phase shifter circuit in accordance with a control signal.
    Type: Grant
    Filed: October 9, 2001
    Date of Patent: April 27, 2004
    Assignee: Fujitsu Limited
    Inventors: Tsuyoshi Moribe, Kazuyoshi Arimura, Susumu Kato
  • Publication number: 20040072548
    Abstract: A transmission circuit comprises the following: a power amplifier whose gain is controlled; a detector which detects a transmission signal from the power amplifier and outputs a detection voltage corresponding to a level of the signal; and a gain controller which compares a transmission power set voltage for setting the level of the transmission signal to be outputted from the power amplifier with the detection voltage and supplies a gain control voltage to the power amplifier. The transmission power set voltage is sent through a low pass filter into the gain controller.
    Type: Application
    Filed: July 16, 2003
    Publication date: April 15, 2004
    Inventor: Jiro Kikuchi
  • Patent number: 6721549
    Abstract: A low-noise amplifier for a mobile communication terminal maintains linearity with the least current consumption. A low-noise amplifier controller detects a signal-to-noise ratio (SNR) of a received signal, and outputs a control signal of a preset voltage when the SNR is lower than a predetermined SNR even though AGC AMP controller increases the AGC gain according to field strength. A bias circuit increases a bias current according to the control signal output from the low-noise amplifier controller. A low-noise amplifier amplifies the received signal to a preset level according to the bias current provided from the bias circuit.
    Type: Grant
    Filed: December 28, 2000
    Date of Patent: April 13, 2004
    Assignee: Samsung Electronics Co., Ltd.
    Inventors: Woo-Yong Lee, Seung-Ki Cho, Se-Young Park, Jae-Min Lee
  • Patent number: 6721547
    Abstract: An embodiment of the present invention provides an automatic gain control system for a wireless receiver that quickly differentiates desired in-band signals from high power out-of-band signals that overlap into the target band. The system measures power before and after passing a received signal through a pair of finite impulse response filters that largely restrict the signal's power to that which is in-band. By comparing the in-band energy of the received signal after filtering to the total signal energy prior to filtering, it is possible to determine whether a new in-band signal has arrived. The presence of this new in-band signal is then verified by a multi-threshold comparison of the normalized self-correlation to verify the presence of a new, desired in-band signal.
    Type: Grant
    Filed: May 4, 2001
    Date of Patent: April 13, 2004
    Assignee: Atheros Communications, Inc.
    Inventors: Paul Husted, Lars E. Thon, William McFarland, Tao Fei Samuel Ng
  • Publication number: 20040063413
    Abstract: An AGC circuit includes both wide-band and narrow-band VGAs. Two power monitors monitor the power level of the two VGAs. Based upon the signals provided by the power monitors, the AGC circuit derives two error terms. The AGC circuit filters and combines the error terms to determine a desired adjustment to the total gain and a desired adjustment to the distribution of the gain between the wide-band VGA and the narrow-band VGA. The AGC circuit also minimizes the noise figure of the narrow-band VGA subject to linearity constraints.
    Type: Application
    Filed: September 24, 2002
    Publication date: April 1, 2004
    Inventors: Troy A. Schaffer, Samir N. Hulyalkar, Anand M. Shah
  • Publication number: 20040053590
    Abstract: A complex filter such as the channel select filter in a radio transceiver is implemented using a transconductance/C topology to benefit from the ability to tune such filters and thereby stabilize the output transfer function of the filter over variations in temperature, power supply voltage and process. The topology is based on an active R/C biquadratic topology to achieve the additional benefit of independently controlled stages. The problem created by the R in the output impedance is can be overcome by separately tuning the R value along with the transconductance/C ratio, by implementing the R as a transconductance amplifier having common mode feedback, or by implementing the transconductance amplifiers of the topology using Nauta transconductors, and unbalancing the common mode circuit of the Nauta transconductor to achieve a differential resistance that can be used to implement the R in the output impedance.
    Type: Application
    Filed: January 16, 2003
    Publication date: March 18, 2004
    Applicant: Broadcom Corporation
    Inventor: Bojko F. Marholev
  • Patent number: 6708025
    Abstract: At the power-on, a determination section (9) outputs a switch control signal (m) to a selector switch (7) to select the output of a sweep signal generator (6) which generates a voltage sweep signal (h) that increases from the minimum value to the maximum value of the gain control voltage range (p) at the same time, then provides the voltage sweep signal (h) to the variable gain amplifier (1), and calculates the difference (f) between the level detection value of an output signal (c) and a convergence value (e) and detects a sweep voltage value (j) obtained when (f)=0 and stores the sweep voltage value (j) into memory. After the sweep operation, the sweep voltage value (j) stored in memory is provided as a gain control signal (b) to the variable gain amplifier (1). Then the primary automatic gain control via the closed loop control system is started.
    Type: Grant
    Filed: February 16, 2001
    Date of Patent: March 16, 2004
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Yasushi Iwata, Yasufumi Ichikawa
  • Patent number: 6687489
    Abstract: The invention provides systems, methods, and devices that compensate for temperature, frequency, and sampling effects in a broadband communication device's power measurements. One embodiment of a system includes a thermal device, and an automatic gain control circuit coupled to the thermal device. One method includes the acts of disabling a TOP operation, setting a RF input power, reading an AGC GAIN value, and setting the broadband communications device based on the read AGC value. Furthermore, a broadband communications device according to the invention may operate by disabling a TOP operation, setting a RF input power, reading an AGC GAIN value, and setting the broadband communications device based on the read AGC value.
    Type: Grant
    Filed: November 15, 2000
    Date of Patent: February 3, 2004
    Assignee: Texas Instruments Incorporated
    Inventor: Adam Lapid
  • Patent number: 6687490
    Abstract: A transmission apparatus with reduced current consumption for a mobile terminal is disclosed. The transmission apparatus includes an automatic gain control (AGC) amplifier for AGC-amplifying an input baseband signal; an attenuator for attenuating an output signal of the AGC amplifier; a multiplier for multiplying an output signal of the attenuator by a carrier frequency signal to convert the signal into a radio frequency (RF) signal; a first filter for filtering an output signal of the multiplier; a drive amplifier for amplifying an output signal of the first filter; a second filter for filtering an output signal of the drive amplifier; a power amplifier for amplifying an output signal of the second filter; and an antenna. When output power of the mobile terminal is lower than predetermined maximum output power of the AGC amplifier, the output signal of the AGC amplifier is transmitted through the multiplier, the first filter and the antenna.
    Type: Grant
    Filed: December 29, 2000
    Date of Patent: February 3, 2004
    Assignee: Samsung Electronics Co., Ltd.
    Inventor: Han-Jun Yi
  • Publication number: 20040009758
    Abstract: Apparatus and a method for fast attack automatic gain control (AGC) loop for narrow band systems in which RF signals are received in discontinuous bursts, such as TETRA systems in a direct mode of operation (DMO). The loop includes a feedback loop with a predetermined non-linear response to an input signal. The method includes the steps of opening the AGC loop (250), setting a gain for the signal path of the AGC loop to a predetermined level (252), closing the AGC loop (254) and commencing a steady-state mode of operation (258).
    Type: Application
    Filed: June 12, 2003
    Publication date: January 15, 2004
    Inventors: David James Graham, Victor Korol, Mark Rozental
  • Patent number: 6678509
    Abstract: An apparatus for use in a receiver in a communication system in which signals cover a wide range of power levels. The apparatus provides reduced power consumption without sacrificing receiver sensitivity by using an amplifier having a fixed, relatively narrow dynamic range that can by selectively positioned to accommodate the wide range of power levels. The amplifier is placed earlier in the receiver signal processing chain than comparable amplifiers in conventional receivers.
    Type: Grant
    Filed: October 15, 2001
    Date of Patent: January 13, 2004
    Assignee: Telefonaktiebolaget LM Ericsson (publ)
    Inventors: Karin Skarman, Tomas Stolt, Anders Järleholm
  • Publication number: 20040002313
    Abstract: An audio level control system for dynamically controlling the level of an input audio signal 9 to provide an altered, level controlled output signal 10. The level control system includes a frequency band limiter 1, a tapped delay line 2, a signal level control stage in the form of a multiplier 3, a zero-crossing detector 6 and a transfer characteristic shaping unit 8. A signal whose level is to be controlled is put into the delay-line 2, and at each zero-crossing of the delayed signal, the maximum amplitude of the signal in the delay line 2 is determined and provided to the transfer characteristic shaping unit 8 which uses that value to adjust the amount of level control applied to the input signal in the level control stage multiplier 3. This provides dynamic level control that adjusts the output signal level gain depending on what the signal is about to do, rather than on the basis of what the signal has just done.
    Type: Application
    Filed: June 28, 2002
    Publication date: January 1, 2004
    Inventors: Allan Peace, John Wright
  • Publication number: 20040002312
    Abstract: The baseband receiver provides a baseband process operating on a receiver in a communication system, such as an 802.15.4 communication system. The baseband process digitizes a baseband signal, and uses less than the full resolution of the digitized data to perform an automatic gain control. In another aspect of the baseband receiver a data frame is detected using less than the full resolution of the digitized data, and without the need for prior synchronization. After a frame is detected, the baseband signal is correlated with reference signals from a set of predefined reference signals, and the reference signal with the best correlation is identified. By identifying the best correlating reference signal, the baseband process is able to identify a characteristic of the baseband signal.
    Type: Application
    Filed: June 5, 2003
    Publication date: January 1, 2004
    Inventors: Liang Li, Liang Zhang, Noi Bangvong, Chenyang Yang, Zhen Zhen Chen
  • Patent number: 6670901
    Abstract: A dynamic range on demand radio frequency (RF) receiver (300) includes a wideband detector (303), off-channel detector (313) and on-channel detector (327) supplying input to an automatic gain control (307) for adjusting a dynamic control stage to control dynamic range and resolution of digital baseband signals (329, 331).
    Type: Grant
    Filed: July 31, 2001
    Date of Patent: December 30, 2003
    Assignee: Motorola, Inc.
    Inventors: Daniel E. Brueske, Babak Bastani
  • Patent number: 6668172
    Abstract: A reception apparatus and a reception processing method are proposed to improve a reception characteristic by compensating deterioration of transmission quality independently of the traveling speed of a terminal. When a transmission signal sent via a radio transmission path is received and data is demodulated by carrying out various kinds of reception processing on the received signal, the present invention can perform reception processing best suited to a radio transmission path whose state changes according to the traveling speed of the terminal itself by receiving traveling speed information from speed detection means for detecting the traveling speed of the terminal itself and controlling reception processing on the reception signal according to the traveling speed information.
    Type: Grant
    Filed: October 27, 2000
    Date of Patent: December 23, 2003
    Assignee: Sony Corporation
    Inventor: Osamu Yoshimura
  • Publication number: 20030232609
    Abstract: A switchable gain amplifier for use in mobile communications devices is provided, having a first amplifier stage having a first gain, a second amplifier stage connected in parallel with the first amplifier stage. The first and second amplifier stage have different gains and a gain controller, connected to the first amplifier stage and to the second amplifier stage, enables only one of the amplifier stages at a time.
    Type: Application
    Filed: June 14, 2002
    Publication date: December 18, 2003
    Inventor: David L. Yates
  • Patent number: 6664849
    Abstract: A digital FM demodulator converts a digital FM input signal to a demodulated signal, detects the amplitude of the digital FM input signal, generates a corresponding amplitude signal, and adjusts the amplitude of the demodulated signal according to the amplitude signal, thereby compensating for variations in the amplitude of the digital FM input signal and removing amplitude distortion from the demodulated signal. This reduces the performance requirements of, for example, a low-pass analog filter preceding the digital FM demodulator in an FM radio broadcast receiver, permitting the analog filter to be implemented in a semiconductor integrated circuit.
    Type: Grant
    Filed: July 12, 2000
    Date of Patent: December 16, 2003
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Kenichi Taura, Masayuki Tsuji, Masahiro Tsujishita, Masayuki Ishida
  • Publication number: 20030224752
    Abstract: A filter module for reducing a DC offset voltage in a radio frequency communication channel is described. A first capacitor is coupled between a first differential input node and a first differential output node. A second capacitor is coupled between a second differential input node and a second differential output node. An active variable resistor is coupled between the first differential output node and the second differential output node. The active variable resistor receives a control signal. The control signal adjusts the value of the active variable resistor, which adjusts the frequency response of the filter module. The rate at which the filter module reduces DC offset voltages is thereby adjusted. The filter module is also adaptable to single-ended applications.
    Type: Application
    Filed: November 8, 2002
    Publication date: December 4, 2003
    Applicant: ParkerVision, Inc.
    Inventors: Gregory S. Rawlins, Kevin Brown, Michael W. Rawlins, David F. Sorrells
  • Patent number: 6658242
    Abstract: A wireless telephone system comprises a base transceiver having a base receiver and a plurality of wireless handsets. Each handset comprises a handset transceiver for establishing a time-division multiple access (TDMA) link over a shared channel with the base unit via the base transceiver, in which each handset communicates during an exclusive time slot of a TDMA scheme that allocates time slots to handsets. The base receiver is characterized by a plurality of demodulation parameters and is for synchronizing with each handsets. The base receiver stores a set of demodulation parameters for each handset and switches to the set of demodulation parameters for a particular handset when the base unit is to synchronize with the particular handset.
    Type: Grant
    Filed: November 9, 2000
    Date of Patent: December 2, 2003
    Assignee: Thomson Licensing S.A.
    Inventors: Paul Gothard Knutson, Kumar Ramaswamy, Dong-Chang Shiue
  • Publication number: 20030220085
    Abstract: In time divisioned, multi-frequency communication air interfaces it is common for a control channel to be defined on a first frequency while traffic channels are carried on other frequencies. A mobile communication device maintains the automatic gain control (AGC) settings for a first frequency while engaged on a second frequency by adjusting the AGC of the first frequency to correspond with changes in the AGC setting for the second frequency before attempting to access the first frequency again. Since, in the communication system, the two signals are transmitted from the same point, the changes in signal level will typically be similar enough that the mobile communication device will not have to perform a new AGC determination when switching back to the first frequency.
    Type: Application
    Filed: March 27, 2002
    Publication date: November 27, 2003
    Inventors: Charbel Khawand, Jean Khawand, Michael A. Heck
  • Patent number: 6654594
    Abstract: An automatic gain control (AGC) system (100) for a controlled gain receiver (1101) includes a magnitude generator (160) and a gain corrector (170). The magnitude generator (160) generates a binary voltage squared signal (165) having a binary value that is directly proportional to a recovered signal power of an intercepted signal (113). The gain corrector (170) determines an adjustment of a gain control value (195) as a multiple of increments that are approximately 3 decibel (dB), by shifting (475, 445) a reference threshold by one or more bits and comparing (485, 455) the shifted reference threshold to the binary voltage squared signal. An initial setting of a state of a step attenuator (114) during a track mode (172) is determined during a warm up mode (171) by comparing the binary voltage squared signal (165) to two different thresholds (245, 255).
    Type: Grant
    Filed: May 30, 2000
    Date of Patent: November 25, 2003
    Assignee: Motorola, Inc.
    Inventors: James David Hughes, John Richard Oakley, Clinton C Powell, II
  • Patent number: 6650878
    Abstract: An automatic gain controller and a receiver having the automatic gain controller, which obtains a stable fine reception quality without influences of the receiving channel or the receiving radio wave is provided. It is provided with the reception quality detector 20 for detecting the reception quality of the diffusion of the constellation, the error correction ratio or the error rate, so as to setup the optimal standard revel (TOP) by switching the reference level (TOP) for switching the IF_AGC operation and the RF_AGC operation according to the reception quality. As a result, it determines the degradation of the reception quality caused by the non-linear distortion or the insufficiency of the C/N according to the radio frequency efficiency that differs from each channel or the receiving radio wave such as a level of the adjacent channel, so as to setup the optimal receiving condition.
    Type: Grant
    Filed: September 29, 2000
    Date of Patent: November 18, 2003
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Shuji Abe, Katsuya Kudo
  • Publication number: 20030207675
    Abstract: An automatic gain control system (100) and methods thereof for a receiver for providing a wide range of continuous gain control has been discussed. The AGC includes an input stage (120) for providing an indication of a strength of a received signal; an attenuator stage (107) operable to switch a fixed amount of attenuation for the received signal; a variable attenuator (109) to provide a variable amount of attenuation for said received signal, and a controller (135) responsive to said indication for providing a variable control signal (145) to the variable attenuator; wherein the controller concurrently changes the variable control signal to change in the opposite direction the variable amount of attenuation by approximately the fixed amount of attenuation whenever the attenuator stage is switched, thereby extending the range of continuous gain control beyond the range of the variable attenuator.
    Type: Application
    Filed: May 3, 2002
    Publication date: November 6, 2003
    Applicant: MOTOROLA, INC.
    Inventors: James David Hughes, Lynn R. Freytag, John Richard Oakley
  • Publication number: 20030207673
    Abstract: In order to provide a constant current source circuit which is capable of covering variety of specifications in a single circuit, there is provided a constant-current source circuit provided having a desired temperature characteristic with a current regulation being set at a predetermined value, in which a first current unit generates a first constant current based on a first resistor connected between a pin and the ground; a second current unit generates a second constant current based on a second resistor connected between a pin and the ground; an adder adds the first and second constant currents; a current amplifying unit generates a third constant current by adding the constant-currents and then multiplying n-fold to inflow or outflow the third constant current via the pin; a current regulation of the third constant current is set at a predetermined value by determining the resistances of the first and second resistors.
    Type: Application
    Filed: May 21, 2001
    Publication date: November 6, 2003
    Inventor: Syuuichi Takayoshi
  • Patent number: 6643498
    Abstract: A signal processing unit 107 outputs a control parameter of a gain control operation-starting electric field strength value in the form of a signal CN1 in correspondence with data of transfer speed/number of FM level by referring to a memory 108. Then, this signal processing unit 107 controls setting of an Received Signal Strength Indicator 105. When an electric field strength of a signal reaches an operation-starting electric field strength value, the Received Signal Strength Indicator (RSSI) 105 changes a voltage of an output GC1 based upon the control parameter (signal CN1). A gain control circuit 106 changes a gain control amount in response to the output signal GC1 derived from the Received Signal Strength Indicator 105. As a consequence, the operation-starting electric field strength value of the AGC operation can be set under optimum condition in correspondence with the sort of signal.
    Type: Grant
    Filed: March 27, 2000
    Date of Patent: November 4, 2003
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventor: Yoshinori Miyajima
  • Publication number: 20030203726
    Abstract: An automatic gain controller for transceiver elements uses a digital topology to achieve an efficient and rapid gain settling so that an output signal of the variable gain section is within a predefined range. In one embodiment, an input signal is periodically sampled and latched so as represent the gain excess of a variable gain section. An accumulator, including an adder having saturation characteristics and a latch as a feedback element, creates a number for a new gain setting so that the variable gain section may adapt to the new gain setting within one clock period. In one example, a gain range of 84 dB is controllable and settling is achieved within 3 clock periods at most.
    Type: Application
    Filed: September 27, 2002
    Publication date: October 30, 2003
    Inventors: Wolfram Kluge, Lutz Dathe, Dietmar Eggert
  • Publication number: 20030203727
    Abstract: In a direct conversion radio frequency receiver, an automatic gain control is implemented that allows changing the operation mode of a filter unit in the baseband section of the receiver such that in a first operation mode filter capacities are selected to provide desired output signal characteristics, whereas in a second operation mode the filter settling time is significantly reduced in order to speed up gain adaptation and to improve gain loop stability. In one embodiment the cut-off frequency of a high pass filter and the Q-factor of a subsequent low pass filter are increased and decreased respectively upon changing the gain setting of a variable gain amplifier to accelerate settling of the filter.
    Type: Application
    Filed: October 31, 2002
    Publication date: October 30, 2003
    Inventors: Wolfram Kluge, Lutz Dathe, Jorg Honig
  • Publication number: 20030194981
    Abstract: A system and method for estimating the power-level of a signal received at a mobile-station receiver operating in a wireless network according to a CDMA standard. An analog automatic gain controller (AGC) loop, a digital filter, and a digital AGC loop are used, in sequence, to process a received RF signal that has been amplified, converted to baseband, and filtered using an analog baseband signal. The linear gain values of the analog AGC and the digital AGC are multiplied to produce a gain-value product. The logarithm of the gain-value product is used for executing the power-estimating function by comparison to a predetermined received-signal power estimation curve.
    Type: Application
    Filed: April 10, 2002
    Publication date: October 16, 2003
    Inventors: Roberto Rimini, Nick Carbone
  • Publication number: 20030186664
    Abstract: Techniques are disclosed for compensating for second-order distortion in a wireless communication device. In a zero-intermediate frequency (IF) or low-IF architecture, IM2 distortion generated by the mixer (20) results in undesirable distortion levels in the baseband output signal. A compensation circuit (104) provides a measure of the IM2 distortion current independent of the radio frequency (RF) pathway to generate an IM2 calibration current. The IM2 calibration current is combined with the baseband output signal to thereby eliminate the IM2 currents generated within the RF pathway. In one embodiment, the calibration is provided at the factory during final testing. In alternative embodiment, additional circuitry (156, 158) may be added to the wireless communication device to provide a pathway between the transmitter (150) and the receiver (146). The transmitter signal is provided to the receiver to permit automatic calibration of the unit.
    Type: Application
    Filed: February 1, 2002
    Publication date: October 2, 2003
    Inventor: Peter Jivan Shah
  • Patent number: 6628932
    Abstract: An aviation radio receiver provides automatic gain control in three zones including an RF zone employing an RF attenuator (14), an intermediate frequency zone employing an intermediate frequency logarithmic attenuator (26) and a baseband zone implemented in a digital processor (30).
    Type: Grant
    Filed: September 29, 2000
    Date of Patent: September 30, 2003
    Assignee: Northrop Grumman Corporation
    Inventor: Michael H. Myers
  • Patent number: 6628731
    Abstract: The invention pertains to a method for controlling the signal level in a digital receiver, wherein the level of a received analog signal is controlled in an analog control circuit (35), whereafter the level of the analog signal coming from the analog control circuit (35) is controlled in a digital control circuit (34), the analog signal is converted into a digital signal in an A/D converter (13) and the amplification factor of the digital control circuit (34) is adjusted on the basis of the signal level of the digital signal coming from the A/D converter (13). The invention also pertains to an apparatus (30) for controlling signal levels in a digital receiver, said apparatus (30) comprising at least an analog control circuit (35) to control the level of an analog signal and a digital control circuit (34) to control the level of the analog signal produced by the analog control circuit (35).
    Type: Grant
    Filed: June 30, 1999
    Date of Patent: September 30, 2003
    Assignee: Nokia Technology GmbH
    Inventors: Tommi Auranen, Petri Vasenkari
  • Publication number: 20030181178
    Abstract: Saturation of an RF front end in a radio receiver is prevented when receiving a desired radio broadcast signal via an antenna in the presence of a strong, undesired radio broadcast signal within a passband of the RF front end. An antenna signal from the antenna is coupled to the RF front end, thereby generating an amplified signal. The radio receiver demodulates the desired radio broadcast signal in response to the amplified signal, thereby generating a demodulated signal. A signal-to-noise quality parameter of the demodulated signal is determined. The antenna signal is attenuated prior to coupling it to the RF front end by an attenuation determined in response to the signal-to-noise quality parameter.
    Type: Application
    Filed: March 25, 2002
    Publication date: September 25, 2003
    Inventors: Richard D. Zerod, Jack H. King
  • Patent number: 6625433
    Abstract: An automatic gain control (AGC) system controls a receiver having multiple amplifier stages with near constant compression. The AGC system controls gain, and thus compression, of each stage employing information generated by the other stages to generate feedback signals at a system level. A central controller uses threshold detection to monitor signal power at each stage of the receiver signal path as well as overall signal gain. Based on these various signal power measurements, the central controller adjusts signal gain of the input to one or more stages, while maintaining overall signal gain for a constant output signal level. The AGC function may be implemented by switching the gain of each stage's variable amplifier in discrete steps in discrete steps, with the step size being coarser for stages closer to the input signal than those closer to the final output baseband signal.
    Type: Grant
    Filed: September 29, 2000
    Date of Patent: September 23, 2003
    Assignee: Agere Systems Inc.
    Inventors: John R. Poirier, Christopher J. Strobel
  • Publication number: 20030176174
    Abstract: A method is disclosed for operating a RF receiver of a communications equipment, as is circuitry for implementing the method. The method includes, while operating under the control of a data processor of the communications equipment, generating a calibration signal; injecting the calibration signal into a low noise amplifier (LNA) of the RF receiver; measuring a downconverted response of the receiver at a plurality of different frequencies of the calibration signal, or measuring the downconverted response of the receiver at a plurality of different LNA tuning combinations using a fixed calibration frequency, and at least one of tuning a resonance frequency of at least one LNA resonator based on the measured downconverted response so as to compensate at least for variations in component values that comprise the at least one resonator, or adjusting the linearity of the receiver.
    Type: Application
    Filed: March 15, 2002
    Publication date: September 18, 2003
    Applicant: Nokia Corporation, Espoo Finland
    Inventors: Pauli Seppinen, Aarno Parssinen, Mikael Gustafsson, Mika Makitalo
  • Publication number: 20030171103
    Abstract: A novel wireless point to multipoint communication system which maximizes the number of remote stations capable of communicating with a base station is disclosed. Independent gain control of the transmitter on the remote stations as a function of the distance between the remote station and the base station is used. The gain control may be accomplished by attenuators in the RF transmit circuit of the remote stations. The attenuators may be placed immediately preceding the RF amplifiers in the RF transmit circuit of the remote stations. The amount of attenuation of the attenuators may be controlled by a microprocessor. By minimizing the gain from the remote station transmitters, the noise floor of the base station receiver is minimized thereby increasing the performance of the base station receiver. This increase in performance permits more remote stations to communicate with the base station.
    Type: Application
    Filed: June 27, 2001
    Publication date: September 11, 2003
    Inventor: Nicholas Paul Shields
  • Publication number: 20030162516
    Abstract: A wireless distribution system includes a number of remote units distributed in a coverage area to receive wireless signals and to provide the signals through the distribution system to input ports of a node where the signals are combined, a number of input power monitors operatively connected to one or more of the input ports to determine power levels of signals received at the input ports, variable gain controllers to control signals received at some or all of the input ports, a node to combine a plurality of signals from the plurality of input ports, and a controller to provide control signals to control one or more of the variable gain controllers.
    Type: Application
    Filed: February 25, 2002
    Publication date: August 28, 2003
    Applicant: ADC Telecommunications, Inc.
    Inventor: Jeff Solum
  • Publication number: 20030148747
    Abstract: There is provided a radio base station which can automatically correct variation in gain of a mast head amplifier and variation in transmission loss due to the length, type and maintenance conditions of a feeder and can minimize an error of the gain of a received signal.
    Type: Application
    Filed: February 5, 2003
    Publication date: August 7, 2003
    Applicant: NEC Corporation
    Inventor: Osamu Yamamoto
  • Publication number: 20030143967
    Abstract: An AMPS receiver system utilizing a ZIF architecture and processing received forward link signals in the digital domain. The AMPS receiver system includes an antenna (105), a direct converter (110), high dynamic A/D converters (120,130), low pass filters (140, 150), a phase shifter (160), a digital VGA (170), a digital FM demodulator (180), an accumulator (185) and a controller (190). The direct converter (110) further includes a low noise amplifier (112), a splitter (113), mixers (114,116) and low pass filters (118,119). The controller (190) adjusts the gains of the low noise amplifier (112) and the digital VGA (170) based on the average power of the signal outputted by the digital VGA (170).
    Type: Application
    Filed: May 31, 2002
    Publication date: July 31, 2003
    Inventors: Steven C. Ciccarelli, Arun Raghupathy
  • Publication number: 20030139160
    Abstract: An automatic gain control circuit with a very wide operational range, less hardware, and faster response, and more flexibility includes a signal strength estimator, a gain adjusting factor device and a multiplier. After the signal strength estimator finds signal strength, the gain adjusting factor device will generate a gain adjusting factor corresponding to the signal strength. Then the multiplier will update gain by multiplying it the gain adjusting factor.
    Type: Application
    Filed: January 22, 2002
    Publication date: July 24, 2003
    Inventor: George L. Yang
  • Patent number: 6590619
    Abstract: A semiconductor integrated circuit in which a band-pass filter, a sound detector, and some other circuits are formed on a single semiconductor substrate. The output signal from an AM detector is passed through a high-pass filter to obtain, substantially, an FM sound signal. A gain variable amplifier controls the amplitude of the FM sound signal and passes the signal through the band-pass filter to extract substantially, an FM sound carrier signal. The amplitude detector monitors the amplitude of the sound carrier signal and applies negative feedback to the gain variable amplifier so that the amplitude is kept constant. Thus, the influence of noise from the band-pass filter is reduced, and degradation of signal-to-noise ratio can be prevented.
    Type: Grant
    Filed: September 9, 1999
    Date of Patent: July 8, 2003
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Tsutomu Kawano
  • Patent number: 6591092
    Abstract: A gain of a broadcast signal receiver for the digital audio broadcast (DAB) system is controlled in order to obtain an output signal of a predetermined level using an AGC loop. The DAB signal of the DAB system includes a Guard Interval within an interval of each symbol, and the Guard Interval does not include valid data to be recovered. Accordingly, the gain change of the AGC loop is done within the Guard Interval in order to avoid signal distortion in the output signal, thereby the DAB receiver having high fidelity is achieved with low cost.
    Type: Grant
    Filed: July 31, 2000
    Date of Patent: July 8, 2003
    Assignee: Sony Corporation
    Inventor: Tatsuya Tsuruoka
  • Patent number: 6577852
    Abstract: When an input signal S11 is variable-gain-amplified by a variable gain amplifier 1 to obtain a predetermined output signal S12, a variable gain control signal S15 is generated by a detecting circuit 2, an A/D converter 3, an adder 4, and a converting unit 5. Both a latch circuit 6 and an adder 7 calculate a difference between a variable gain control signal generated during a preceding control operation and a present variable gain control signal. When the difference result is equal to “0”, a counter 8 counts predetermined stable condition continued time, and thereafter outputs a non-operation setting signal S16. Also, the counter 8 sends out the variable gain control signal generated during the preceding control operation to the variable gain amplifier 1 so as to set the detecting circuit 2, the A/D converter 3, the adder 4, and the converting unit 5 into non-operation conditions thereof.
    Type: Grant
    Filed: July 5, 2000
    Date of Patent: June 10, 2003
    Assignee: Matsushita Electric Industrial Co., Ltd.
    Inventors: Yasushi Iwata, Yasufumi Ichikawa
  • Publication number: 20030100281
    Abstract: Automatic gain control (AGC) functionality is distributed within a transmitter chain.
    Type: Application
    Filed: November 29, 2001
    Publication date: May 29, 2003
    Applicant: D.S.P.C. TECHNOLOGIES LTD
    Inventor: Eliav Zipper
  • Publication number: 20030100282
    Abstract: A system adjusts a receiving device in response to sensing symbols. An automatic gain control is adjusted in response receiving a first symbol of a data unit from a first antenna. After adjusting the automatic gain control at least a second and a third symbol of the data unit are received, and in response thereto (1) a first energy of at least one of the second and third symbols is calculated, (2) a first frequency offset of at least one of the second and third symbols is calculated, and (3) a first temporal offset of at least one of the second and third symbols is calculated. The automatic gain control in response receiving a fourth symbol of the data unit from a second antenna is received.
    Type: Application
    Filed: January 6, 2003
    Publication date: May 29, 2003
    Inventor: Srinivas Kandala
  • Patent number: 6570929
    Abstract: A method and apparatus for maximizing the signal-to-noise ratio of an output signal from a digital-to-analog converter. In a multicarrier transmitter the power of a plurality of modulated digital data streams are individually adjusted so that the peak power of the sum of the signals of the modulated data streams is equal to a full scale level of a digital-to-analog converter. The power adjusted signals are upconverted to their respective carrier frequencies and combined into a single digital data stream by an adder. The single digital data stream is converted into an analog data stream by the digital-to-analog converter. The power of the analog data stream is adjusted so that the power of each carrier frequency is at a level which provides a corresponding mobile station with a signal of acceptable quality.
    Type: Grant
    Filed: July 8, 1999
    Date of Patent: May 27, 2003
    Assignee: Telefonaktiebolaget LM Ericsson (publ)
    Inventor: Patrik Eriksson
  • Patent number: 6571083
    Abstract: An automatic simulcast correction method (300) for a selective call receiver (100) includes the steps of measuring a received signal (304) for a received signal strength indication measurement and then determining if a protocol indicates a simulcast signal (310). If the received signal strength indication measurement is above a predefined threshold and the protocol indicates the simulcast signal, then the selective call receiver is optimized for simulcast delay spread distortion (312). If the received signal strength indication measurement is below a predefined threshold or the protocol does not indicate the simulcast signal, then the selective call receiver is optimized for static sensitivity (314).
    Type: Grant
    Filed: May 5, 1999
    Date of Patent: May 27, 2003
    Assignee: Motorola, Inc.
    Inventors: Clinton C Powell, II, James David Hughes, Chun-Ye Susan Chang, Christopher T. Thomas, Mahibur Rahman, Edgar Herbert Callaway, Jr., James A. Kimball
  • Publication number: 20030092410
    Abstract: A control word generator comprised of circuitry to generate a control word to control an attenuator. The control word generator includes a counter that increments at a clock rate much higher than the refresh rate at which the error signal is recalculated. The counter is controlled by a comparator which compares the error signal to a reference value, which, starting from a programmable upper limited is decremented in the counter's incrementation rate by a programmable step size. When the reference value equals the error signal, the comparator changes state and the counter stops incrementing. The count at that time is the control word, which if everything operated instantaneously, would be the control word that would alter the attenuation sufficiently to achieve nominal power.
    Type: Application
    Filed: November 15, 2001
    Publication date: May 15, 2003
    Inventor: Syed Habib Rahman