Abstract: A signal gain control circuit. A gain stage receives and amplifies an analog signal by a first gain factor adjusted by a gain adjusting signal in a periodic manner with a first period, and outputs an amplified signal. An analog to digital converter converts the amplified signal to a first digital signal comprising a stream of samples. An amplifying device adjusts a second gain factor in a periodic manner with a second period in accordance with a characteristic metric of the distribution of the first digital signal and multiplying the first digital signal by the second gain factor to generate a second digital signal. A first gain adjusting device detects a strength of the second digital signal and generates the gain adjusting signal according to the signal strength of the second digital signal in a periodic manner with the first period.

Abstract: A direct current (DC) offset correction system for a direct conversion receiver and corresponding receiver and methods facilitate reduction of DC offsets in such receivers. One method includes calibrating a DC offset correction system in a closed loop configuration over each of a plurality of gain settings to provide a plurality of offset data for an operating mode of the direct conversion receiver; selecting one of the plurality of offset data based on a current gain setting of the direct conversion receiver as supplied, e.g., by an AGC system; and operating the DC offset correction system in an open loop configuration using the one of the plurality of offset data to correct for a DC offset in the direct conversion receiver.

Abstract: A cascadable AGC amplifier in a signal distribution system includes a low noise cascadable amplifier having a through path and a cascadable output. The cascadable amplifier is also configured to provide AGC over a predetermined input power range. The cascadable AGC amplifier can be configured to provide gain or attenuation. When the cascadable AGC amplifier is implemented in a signal distribution system, typically as part of a signal distribution device, an input signal can be gain controlled and supplied to multiple signal paths without distortion due to degradation of signal to noise ratio or distortion due to higher order amplifier products. The distributed signal is not significantly degraded by distortion regardless of the number of cascadable AGC amplifiers connected in series or the position of the cascadable AGC amplifier in the signal distribution system.

Abstract: A cascadable AGC amplifier in a signal distribution system includes a low noise cascadable amplifier having a through path and a cascadable output. The cascadable amplifier is also configured to provide AGC over a predetermined input power range. The cascadable AGC amplifier can be configured to provide gain or attenuation. When the cascadable AGC amplifier is implemented in a signal distribution system, typically as part of a signal distribution device, an input signal can be gain controlled and supplied to multiple signal paths without distortion due to degradation of signal to noise ratio or distortion due to higher order amplifier products. The distributed signal is not significantly degraded by distortion regardless of the number of cascadable AGC amplifiers connected in series or the position of the cascadable AGC amplifier in the signal distribution system.

Abstract: Multi-segment gain control system. Apparatus is provided for a multi-segment gain control. The apparatus includes logic to convert a gain control signal to an exponential signal, and logic to map the exponential signal to multiple control signals that are used to control multiple gain stages to produce linear multi-segment gain control.

Abstract: A reception apparatus capable of calibrating a DC offset voltage fast and with high accuracy even in an environment in which interferer exist without causing noise characteristic degradation. In this apparatus, a digital signal processing section (108) controls the gain of a received signal at such a gain that predetermined reception quality is obtained. A time constant control circuit (110) controls the time constant and makes the amount of attenuation of the received signal of a low pass filter (106a) more moderate compared to the case where a DC offset voltage is not calibrated during DC offset voltage calibration. A voltage calibration circuit (111) calibrates the DC offset voltage generated in the received signal when controlling the gain.

Abstract: A wireless local area network (WLAN) system can have multiple antennas to improve signal detection and decoding. A WLAN receiver in such a system includes multiple amplifiers that can appropriately size an incoming signal and an automatic gain control unit to process the received incoming signals. The amplifiers of a chain of the WLAN receiver, i.e. an antenna and associated receiver components, can be adjusted with computed gains. To optimize the wireless system detection and decoding, the automatic gain control unit can advantageously compute these gains for each amplifier in the WLAN receiver.

Abstract: A receiver (100) adjusts its overall gain based on the detected power level of an incoming signal. The receiver is built with two detectors (D1, D2) which operate with different detecting ranges within the dynamic range of the incoming signal. If the actual power level of the incoming signal falls within one of the resolving ranges, an automatic gain control adjusts the gain of the receiver to a corresponding gain value. If not, the resolving range of one of the two detectors is shifted and eventually reduced to cover the portion of the dynamic range in which the power level is comprised. The gain of the receiver is then temporarily adjusted and a new measurement is carried out by the detector using the new resolving range. The AGC then re-adjusts the gain of the receiver based on the measurement given by the modified detector.

Abstract: An integrated tuner is programmable to optimize its components for either analog signal reception or digital signal reception. Power to the components is increased for analog operation and decreased for digital operation. The tuner also includes a selectable and integrated low noise amplifier that may be selected for single-signal reception and bypassed for multi-signal reception.

Abstract: The present invention relates to wireless communications, and in particular although not exclusively, to networks of indoor collocated or overlapping wireless coverage areas especially those intended for operation in unlicensed spectrum such as the Industrial Scientific and Medical (ISM) bands.

Abstract: The present invention is to provide a dynamic power control circuit for a wireless communication device, which comprises a power detector, a comparator, a low pass filter and an adder disposed between a radio frequency auto-gain control circuit and an antenna thereof. A reference voltage is imposed on the adder to enable the power detector to detect and output signal voltage to the comparator which compares the received voltage with a specified received voltage limit and outputs a reference voltage to the low pass filter for filtering out the noise of the reference voltage and outputting it to the adder. The adder then adds the reference voltage and the specified reference voltage, and outputs the result to the radio frequency auto-gain control circuit for controlling the output power corresponding to the strength of the received signals.

Abstract: Disclosed is an AGC (automatic gain control) device and method of an OFDM system with a DC offset compensation function, and a recording medium storing a program including the method. The AGC device calculates an energy of input signals with DC offsets as the summation of the square of the input signals, and calculates an energy of the DC offsets in the input signals as the summation of the square of the DC offsets. Pure signal energy without DC offsets is produced by subtracting the energy of the DC offsets from the energy of the calculated input signal. The energy and an AGC reference value are then compared, and feedback of a comparison result is performed.

Abstract: An analog signal gain control circuit(ASGC) for a digital radio HomePlug orthogonal frequency division multiplexing (OFDM) receiver includes a digital variable gain amplifier (DVGA) to control the gain of a received signal to achieve a desired signal amplitude to match a dynamic range of an analog-to-digital converter (ADC), an inverse scaling stage controlled to inverse-scale the signal output by the ADC, and a two-stage fast attack and slow decay filter that outputs control signals to the DVGA and to the inverse scaling stage. The fast attack and slow decay filter rapidly responds to an increase in signal amplitude and slowly decays the amplitude of the control signal in response to a decrease in input signal amplitude.

Abstract: A method for maximizing intermodulation interference protection during a handoff between radio cell sites (300) includes scanning a plurality of radio channels (302) and measuring the signal power (307, 315) for at least one of the radio channels. One or more receiver attenuators (313) are then set based on the detection of intermodulation (IM) interference of the measured channel. The attenuators are then scaled (311) based on the degree of IM interference. If the attenuators cannot mitigate this interference below some predetermined level, the radio channel is changed (321) and the process begins again to ensure a high quality of communication with a cell site.

Abstract: A voltage regulator includes a master regulator circuit that receives a reference signal, that generates a master bias signal and that includes a transistor having a first gain. A first slave regulator circuit includes a first transistor having a second gain that is substantially equal to unity gain, a control terminal that receives the master bias signal from the master regulator circuit, a first terminal and a second terminal that outputs a first regulated output signal. A second slave regulator circuit includes a second transistor having a second gain that is substantially equal to unity gain, a control terminal that receives the master bias signal from the master regulator circuit, a first terminal, and a second terminal that outputs a second regulated output signal.

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.

Abstract: A method and device are disclosed for receiving digital television signals by a frequency tuner. The power of the signal is measured after an analog/digital conversion in the frequency tuner, and the gain thereof is controlled on the basis of this power measurement according to a predetermined control law. The power of the analog signal, tapped between an input amplifier stage and a first frequency transposition stage, or immediately after the first frequency transposition stage, is also measured. The measured power is compared with a predetermined power threshold so as to obtain first binary information, and the gain control law is set on the basis of the value of the first binary information.

Abstract: In a radio reception apparatus, a variable gain of a reception amplifier is adjusted by an AGC control unit for each frame of a received signal for execution of an AGC operation. The AGC control unit determines and indicates to a digital signal processing unit an AGC operation end point of time. The digital signal processing unit executes prescribed signal processing on a digital signal obtained after the end of the AGC operation, in a known signal segment. Therefore, reception errors caused by erroneous amplitude values of digital signals resulting from the AGC operation can be prevented.

Abstract: A variable gain amplifier device controlled by a first gain control signal comprises a gain controlled amplifier having a gain and including a differential pair of first and second MOS type transistors configured to operate in a weak inversion region; and a control signal converter configured to convert the first gain control signal into a second gain control signal, and supply the second gain control signal to the gain controlled amplifier to exponentially vary the gain with respect to the first gain control signal.

Abstract: A first AGC voltage and a second AGC voltage are taken from the final stage of a radio-frequency circuit and the output side of a bandpass filter, respectively, and the gain of the radio-frequency circuit is controlled on the basis of the two AGC voltages. The pass-band width of the bandpass filter is approximately two times greater than the frequency interval of FM broadcast signals. The second AGC voltage is set higher than the first AGC voltage in the pass-band of the bandpass filter.

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.

Abstract: A variable gain amplifier device controlled by a first gain control signal comprises a gain controlled amplifier having a gain and including a differential pair of first and second MOS type transistors configured to operate in a weak inversion region; and a control signal converter configured to convert the first gain control signal into a second gain control signal, and supply the second gain control signal to the gain controlled amplifier to exponentially vary the gain with respect to the first gain control signal.

Abstract: A radio-frequency (RF) receiver includes a receiver analog circuitry and a receiver digital circuitry coupled together. The receiver analog circuitry receives an RF signal. The receiver analog circuitry processes the received RF signal and generates a digital signal that it provides to the receiver digital circuitry. The receiver digital circuitry includes a digital down-converter circuitry that mixes the digital signal provided by a receiver analog circuitry with a digital intermediate frequency (IF) local oscillator signal to generate a digital down-converted signal. The receiver digital circuitry also includes a digital filter circuitry that filters the digital down-converted signal to generate a filtered digital signal. The digital filter circuitry provides a notch at a frequency that corresponds to a residual DC offset of the receiver analog circuitry.

Abstract: An A-rail circuit outputs a control signal AGCOUTA whereas a B-rail circuit outputs a control signal AGCOUTB in an AGC circuit. AGCOUTA controls an AGC amplifier (A) while AGCOUTB controls an AGC amplifier (B). A difference value between a power of an input signal and (an amount of variable adjustment SWEEP+a power reference value AGCR). If an output signal of a loop filter in the A-rail circuit attains AGCARAIL>AGCATOB, AGCARAIL=AGCATOB is fixed, and AGCBRAIL is adjusted based on the difference value. If an output signal of a loop filter in the B-rail circuit attains AGCBRAIL<AGCBTOA, AGCBRAIL=AGCBTOA is fixed, and AGCARAIL is adjusted based on the difference value. A control circuit in the AGC circuit acquires a bit error rate, identifies a value of SWEEP allowing a minimum bit error rate, and fixes the value of SWEEP at the identified value.

Abstract: The radio receiver includes a low noise amplifier that amplifies a received signal to one of three different gain settings. One gain setting is maximum amplification, a second gain setting is 6 dB below maximum amplification and a third gain setting is 32 dB below maximum amplification. In the case of the third setting, the low noise amplifier actually attenuates the received signal by 6 dB. The radio receiver includes a pair of received signal strength indicators that provide received signal strength indications to logic circuitry. Responsive to the received signal strength indications, the logic circuitry generates control commands to the low noise amplifier to prompt it to amplify at one of the three specified levels. Generally, if the received signal has a gain level that exceeds a specified threshold, the low noise amplifier actually attenuates the received signal; otherwise, the level of amplification that is actually provided is a function of the presence of intermodulation interference.

Abstract: A transmitter into which a modulated signal (TX) is fed, the transmitter comprising an adjustable amplifier (1) for adjusting transmission power level, the modulated signal (TX) being fed into to the input of the amplifier (1), an amplification branch (11) arranged after the adjustable amplifier (1) on the signal path, the amplification branch comprising a power amplifier (3) for further amplifying the transmission power level, and at least one filter (27, 28) arranged after the power amplifier (3) on the signal path for filtering the frequency band to be transmitted. The transmitter further comprises an antenna (9) after the amplification branch (11) on the signal path for transmitting signals. The transmitted is characterized by a bypass branch (10) which operatively couples the output of the adjustable amplifier (1) and the antenna (9) and is used for bypassing the amplification branch (11) and connecting signals to be transmitted at low transmission power levels directly to the antenna (9).

Abstract: Apparatus, and an associated method, for a direct conversion receiver by which to selectably increase the sensitivity of the receiver. The direct conversion receiver includes a baseband amplifier positioned in front of a baseband filter, and coupled to receive a direct-converted baseband signal. The gain at which the baseband amplifier amplifies the signal provided thereto is selected, in combination with gains applied to other amplification elements of the direct conversion receiver to distribute the gain across the receive chain. When a signal received at the receiver includes a large interfering signal component, the gain of the baseband amplifier is reduced to lessen the possibility that the amplified signal become saturated. A gain controller controls the gain of the amplification elements.

Abstract: An apparatus for providing automatic gain control for use in a satellite terminal of a satellite communication system capable of transmitting a plurality of different modes of data. The apparatus includes a demodulator circuit having an analog to digital converter; a first variable attenuator having an attenuation value set on the basis of a measured power level of a predetermined data signal; and a second variable attenuator having an attenuation value set on the basis of the mode of data being received by the satellite terminal, where each of the data modes have a corresponding predetermined attenuation value associated therewith which is utilized as the attenuation value of the second variable attenuator when the satellite terminal receives the data mode.

Abstract: An improved single-ended input differential pair amplifier stage comprises: 1) a first p-n-p transistor having a base terminal coupled to an input voltage; 2) a first load impedance having a first terminal coupled to a ground reference and a second terminal coupled to a collector of the first p-n-p transistor; 3) a second p-n-p transistor having a base terminal coupled to the ground reference; 4) a second load impedance having a first terminal coupled to a ground reference and a second terminal coupled to a collector of the second p-n-p transistor; 5) an inductor having a first terminal coupled to an emitter of the first p-n-p transistor and a second terminal coupled to an emitter of the second p-n-p transistor; and 6) a constant current source coupled to the emitter of the second p-n-p transistor.

Abstract: A receiving circuit includes a converter 1 of which gain is switched such that the gain is decreased through a plurality of stages in response to an increase in the intensity of the received signal, for converting the received signal into an intermediate frequency signal, and a base band processing circuit 5 for switching the gain of the converter 1. The gain of the converter 1 is switched to the lower level at the output level of the converter 1 corresponding to the minimum level of the received signal input into converter 1 at which an allowable error rate is secured in the base band processing circuit 5 at the maximum gain. When the converter 1 is set up to the maximum gain mode, the level of the intermediate frequency signal is lowered by attenuation means ATT provided in the converter 1.

Abstract: A receiver generates two metrics, one that is used to control the gain of an amplifier and the other that is used to determine the presence of narrowband interference, such as IMD. The two metrics may represent analog-to-digital converter (A/D) saturation and average signal strength, either of which may be used to control gain or to detect the presence of narrowband interference.

Abstract: The automatic gain control method with little being influenced of the unnecessary electric wave, even if strong unnecessary electric wave is near the frequency of input signal, is offered by carrying out change of the delay point level. The automatic gain control system with a scale of few circuit, having low noise property and high adjacent disturbance oppression property, is offered. When the IF AGC signal 112 is smaller than delay point level, the output agcerr of the signal level detector 614 is provided to the 1st loop filter 105. Since the IF AGC signal 112 provided to the IF AGC amplifier 608 is value responding to signal level of IF signal, output is fed back to this amplifier, and control of IF gain is performed automatically. On the other hand, when output of the 2nd loop filter 106 is “0”, output rfzero of the 2nd comparator 108 is set to 1, and “0” is provided to the 2nd loop filter 106.

Abstract: Briefly, in accordance with one embodiment of the invention, a wireless device has an array of antennas. A signal is provided to one of the antenna by two variable gain amplifiers, one of which processes a signal that is shifted in phase compared to the signal processed by the other variable gain amplifier.

Abstract: The invention relates to a hearing aid, preferably a programmable hearing aid, having at least one microphone (1), at least one signal processor with at least one channel, an output amplifier (9) and an output transducer (10), at least one of the channels containing a signal processing circuit (4) with at least one percentile estimator (6) for the continuous determination or calculation of at least one percentile value of the input signal from a continuous analysis and evaluation of the frequency and/or amplitude distribution of the input signal, whereby the percentile value(s) serve either directly or indirectly as control signals for controlling the gain and/or the frequency response of the electronic processing circuit, the percentile estimator (6) consisting essentially of a comparator stage (12) with two inputs and two outputs, the first input being directly or indirectly connected to the input of the hearing aid, its two outputs controlling a first control stage (13) the output signals of which control

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.

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.

Abstract: A radio communication apparatus is provided with a first variable power amplifier 13 and a second variable power amplifier 14 in a radio transmission unit 22, and also a variable amplifier 16 is provided at a prestage of a modulation unit 15. A transmission power control bit is extracted from a reception signal sent from a communication counter station by a variable power amplifying-controlling unit 18. The variable power amplifying-controlling unit 18 updates a value of transmission power stored in an own station based upon the value of this extracted transmission power control bit, and also compares the updated transmission value with a predetermined threshold value. Based upon this comparison result, the first and second variable power amplifier 13 and 14, and the variable amplifier 16 are controlled in either a serial control manner or a parallel control manner so as to perform a variable power amplification, so that the own transmission power is adjusted.

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.

Abstract: A receiver having a digital automatic gain control (AGC) circuit is disclosed for use in a cellular communication system, including a Hierarchical Cellular System. The receiver includes a controller which switches between gain control values depending on system operational mode. In this way, the AGC can be optimized for different types of receive processing operations, e.g., traffic reception and measurement of other channels.

Abstract: An apparatus comprising a first circuit and a second circuit. The first circuit generally comprises one or more master amplifiers and a plurality of control amplifiers. The first circuit may be configured to generate a plurality of control signals in response to (i) a first signal related to a desired gain and (ii) a second signal related to a known reference. The second circuit may be configured to generate an output signal in response to (i) an input signal and (ii) the plurality of control signals. The output signal may be amplified with respect to the input signal.

Abstract: An antenna tuning apparatus for VHF/UHF antenna comprises an automatic gain control (AGC) arrangement, including an amplifier, the gain of which is controlled by the AGC arrangement, and a plurality of impedance matching networks which are coupled between an antenna input of the tuning apparatus and the AGC-controlled amplifier. A remote controller is provided to select both channels of a television apparatus, for which the tuning apparatus provides VHF/UHF signals, and proper matching networks suitable for respective ones of selected channels simultaneously. Each one of the plurality of matching networks exclusively provides the AGC arrangement with a respective group of RF signals which includes a plurality of receivable broadcast channels. The gain of the amplifier is controlled in response to the level of the group of RF signals.

Abstract: The invention relates to an amplification circuit AC comprising a plurality of amplification branches (Di, Hi, ai, where i=1 to N), each one of the branches having a gain proper that makes a contribution to the overall gain of the amplification circuit AC, the size of said contribution being determined by a control signal CNT.

Abstract: There is disclosed a single-ended input differential pair amplifier stage. The single-ended input differential pair amplifier stage comprises: 1) a first n-p-n transistor having a base terminal coupled to an input voltage; 2) a first load impedance having a first terminal coupled to a power supply and a second terminal coupled to a collector of the first n-p-n transistor; 3) a second n-p-n transistor having a base terminal coupled to a ground reference; 4) a second load impedance having a first terminal coupled to the power supply and a second terminal coupled to a collector of the second n-p-n transistor; 5) an inductor having a first terminal coupled to an emitter of the first n-p-n transistor and a second terminal coupled to an emitter of the second n-p-n transistor; and 6) a constant current source coupled to the emitter of the second n-p-n transistor.

Abstract: An object of the present invention is to suppress the generation of a transient voltage in the settings of gains of a plurality of variable gain amplifiers of a baseband circuit. A gain converting circuit provides a limiting value to the quantity of the change of a gain which can be changed once. If gain input data has large change and the gain change exceeding the limiting value is carried out, the quantity of the change is divided into a plurality of quantities of change equal to or lower than the limiting value and variable gain amplifiers are controlled to thereby realize a required gain change. A gain distribution circuit distributes gain control data to the respective variable gain amplifiers on the basis of gain output data of the gain converting circuit.

Abstract: A power amplifier having bias that may be automatically adjusted based on a detected output power level. The amplifier includes one or more amplifier stages operatively coupled to a control unit. The amplifier stage(s) couple together (e.g., in series) and receive and amplify an RF input signal to provide an RF output signal. A power detector detects the RF output signal level (or power) and provides a detected signal. A control unit conditions the detected signal (e.g., with a particular transfer characteristic) to provide at least one conditioned signal. A bias control generator receives the conditioned signal(s) and provides at least one bias control signal, with each bias control signal used to adjust the bias of a respective amplifier stage. The bias adjustment is performed in a manner to achieve the desired level of linearity while minimizing power consumption.

Abstract: A gain control circuit has a transmission power amplifier that amplifies a transmission signal to a predetermined level. An adjacent channel leak power ratio monitor finds a ratio of a distortion element corresponding to an adjacent channel leak power to a main element from an output signal supplied from the transmission power amplifier, and outputs the found ratio as an ACPR monitor value. A power supply control section variously controls power supply to the transmission power amplifier with use of the ACPR monitor value supplied from the adjacent channel leak power ratio monitor. A transmission signal level variable section controls a gain of a transmission signal path on the basis of a transmission level monitor value supplied from the adjacent channel leak power ratio monitor, thereby varying a level of the transmission signal.

Abstract: An amplifier used in a tuner of video and/or audio equipment has to amplify the received input signal but should add as little as possible noise and distortion to the amplified signal. To improve the operation of the amplifier and includes tuner, the amplifier of the at least two gain stages and switches for short-circuiting a gain stage when it is not necessary for the overall gain value.

Abstract: A phase error detector that detects phase error between differential signals. A quadrature oscillator provides in-phase (I) and quadrature phase (Q) differential carrier signals and receives a phase error signal from the phase error detector. The oscillator maintains a quarter cycle phase delay between the I and Q carrier signals based on the phase error signal. The phase error detector includes a summing network and first and second bipolar transistor mixer circuits. The summing network develops four sum signals by summing respective pairs of the differential components of the I and Q carrier signals. A bias circuit biases the transistors to turn on at positive base voltages. The mixer circuits may include filter capacitors so that the transistors are responsive to positive base voltages. The mixer circuits develop polarity signals based on the sum signals, and the resulting phase error signal is the differential of the polarity signals.

Abstract: A digital gain controlled VGA is provided having a built-in decoder allowing for more standardized design of radio receivers by allowing a standardized gain control signal to be sent to the digital gain controlled VGA for controlling gain of the digital gain controlled VGA. Additionally, a digital gain controlled VGA is provided which is able to be controlled using an analog gain control signal. Use of the analog gain control signal allows the problems associated with the fast update rate required by the digital gain control word to be overcome. In addition, a digital gain controlled VGA is provided having a programmable decoder and noise and linearity circuit for changing the noise and linearity characteristics of the digital gain controlled VGA during operation.

Abstract: In an automatic gain control amplifier AGCa, an RF automatic gain controller 2 controls the gain of a radio frequency signal Srf. A frequency converter 3, 4 frequency-converts the radio frequency signal Srfa into an intermediate frequency signal Sifa. An IF automatic gain controller 5 controls the gain of the intermediate frequency Sifa. A level detector LDa detects a signal level of the gain-controlled intermediate frequency signal Sifa, and generates a level signal SLa. An automatic gain control signal generator SGa, SGb separately controls, based the level signal SLa, SLb, the RF automatic gain controller 2 and the IF automatic gain controller 5.