Abstract: A phase-synchronized RF power generator includes: an RF power amplifier for amplifying an RF power signal; a first directional coupler; an isolator for adjusting impedance mismatch generated by the first directional coupler, and transferring the RF power signal transferred by the first directional coupler to the output terminal; a second directional coupler for transferring part of the feedback signal transferred by the first directional coupler to be compared with a frequency of a reference signal provided by a crystal oscillator, and transferring rest of the feedback signal to a feedback loop; a digital phase shifter for adjusting a phase of the feedback signal transferred by the second directional coupler at predetermined intervals; an analog phase shifter for continuously adjusting the phase of the feedback signal discretely adjusted by the digital phase shifter; and a frequency comparator.

Abstract: A bandpass filter that provides a wide gain control range is provided. The bandpass filter performs channel filtering and gain control while maintaining the bandpass characteristic of the bandpass filter. The bandpass filter enables gain control for a wide signal amplitude range while maintaining performance characteristics, such as an out-of-band attenuation ratio capable of high linearity and good pass-band flatness.

Abstract: A switching power-supply device that converts a first DC voltage into a second DC voltage and outputs the second DC voltage by turning on-and-off a switching element connected between the input power source and an inductor, includes: a drive unit, which drives the switching element based on a drive signal; a control unit, which performs intermittent oscillation control; and an error signal generator, which generates an error signal based on an error between a voltage corresponding to the second DC voltage and a reference voltage, wherein the control unit controls a timing, at which the turning-on of the switching element is permitted in the intermittent oscillation control, based on a signal indicating a comparison result between the error signal and a threshold value and an OFF time of the switching element based on the drive signal.

Abstract: This disclosure relates to a signal processing device, a signal processing method, and a receiving device that are capable of detecting response information at a high degree of accuracy from a carrier signal that is load-modulated based on the response information. A positive DC generating unit 61 generates a positive threshold based on a load-modulated carrier signal. A positive selecting unit 62 compares the voltage of the carrier signal with the positive threshold, and outputs the value of the larger one to an adding unit 65. A negative DC generating unit 63 generates a negative threshold based on the load-modulated carrier signal. A negative selecting unit 64 compares the voltage of the carrier signal with the negative threshold, and outputs the value of the smaller one to the adding unit 65. The adding unit 65 adds the output of the positive selecting unit 62 and the output of the negative selecting unit 64, and outputs the addition result to an IQ detecting unit 53.

Abstract: An apparatus includes a voltage divider circuit and a reference amplifier coupled to the voltage divider circuit. The reference amplifier is configured to provide a feedback voltage to input circuitry of an amplifier.

Abstract: There is provided an audio processing apparatus. An obtaining unit obtains an audio signal. A first audio level controller gives a first gain to the audio signal obtained by the obtaining unit. A second audio level controller gives a second gain to the audio signal output from the first audio level controller. A time constant in processing for increasing the first gain of the first audio level controller is larger than a time constant in processing for increasing the second gain of the second audio level controller.

Abstract: According to an embodiment, a method includes amplifying a signal provided by a capacitive signal source to form an amplified signal, detecting a peak voltage of the amplified signal, and adjusting a controllable impedance coupled to an output of the capacitive signal source in response to detecting the peak voltage. The controllable impedance is adjusted to a value inversely proportional to the detected peak voltage.

Abstract: A signal processing device includes: an amplifier, a bandwidth of which can be switched, and a controller which is configured to perform control to operate the amplifier in a wide bandwidth for a constant time after start of a signal input to the amplifier and then operate the amplifier in a narrow bandwidth thereafter.

Abstract: In accordance with an embodiment, a method of controlling a power supply node includes measuring a voltage of the power supply node, determining a first current based on the measuring, determining a first current and a second current based on the measuring, and summing the first current and the second current at the power supply node. Determining the first current includes operating a first controller having a first bandwidth, and determining the second current includes operating a second controller having a second bandwidth greater than the first bandwidth.

Abstract: A system for power amplifier over-voltage protection includes a power amplifier configured to receive a system voltage, a bias circuit configured to provide a bias signal to the power amplifier, and a power amplifier over-voltage circuit configured to interrupt the bias signal when the system voltage exceeds a predetermined value, while the system voltage remains coupled to the power amplifier.

Abstract: An electronic circuit includes an amplifier that amplifies an input signal, a control circuit configured to generate a control signal by averaging an output signal of the amplifier based on a time constant, a first time constant control circuit configured to generate a first time constant control signal based on the control signal, the first time constant control signal changing the time constant of the control circuit to a second time constant from a first time constant smaller than the second time constant, a second time constant control circuit configured to generate a second time constant control signal by averaging the output signal of the amplifier based on a third time constant between the first time constant and the second time constant, the second time constant control signal changing the time constant of the control circuit to the first time constant from the second time constant, and a bypass circuit bypassing the input signal of the amplifier based on the control signal.

Abstract: An amplifier for receiving an optical signal is disclosed. The amplifier provides a response time controller including an integrator with two time constants, a linear amplifier, a hysteresis comparator, an another integrator, and a switch to change the time constant. The switch includes two voltage followers, one of which turns off the switch to set the time constant in a longer state; while, the other of which turns on the switch and reflects the input of the integrator to set the time constant in a shorter state.

Abstract: A measurement system includes a detector to generate a measurement signal responsive to an input signal, and a nulling circuit coupled to the detector to generate a control signal responsive to the difference between the measurement signal and a set-point signal. The nulling circuit may include a bandwidth compensation stage to maintain the overall control loop bandwidth at a substantially constant value.

Abstract: An apparatus including automatic gain control (AGC) includes at least one variable gain amplifier (VGA) operative to receive an input signal and to generate an amplified signal. A gain of the VGA is controlled as a function of at least a first control signal. The apparatus further includes an AGC circuit coupled to the VGA and being operative to generate the first control signal. The AGC circuit has a bandwidth that is controlled as a function of at least the amplified signal and a second control signal, the second control signal being indicative of a motion of the apparatus.

Abstract: An amplifier includes: a variable gain unit that adjusts an amplitude of an input signal and outputs a first signal; an amplitude limiting unit that limits an amplitude of the first signal and outputs a second signal set to have an amplitude of a first amplitude value or less; an amplifying unit that amplifies the second signal to output the amplified second signal as an output signal; and a control unit that detects when the first signal has an amplitude of a second amplitude value or more to control a gain of the variable gain unit so that the amplitude of the first signal becomes less than the second amplitude value, the second amplitude value being larger than the first amplitude value.

Abstract: An automatic gain control circuit includes a first voltage dividing resistor, a filter circuit, a switch circuit, and an amplifying circuit. The first voltage dividing resistor divides a voltage of the automatic gain control circuit using an internal impedance of the audio device to produce a divided DC voltage, wherein the first voltage dividing resistor is connected between a first power source and an output of the audio device. The filter circuit filters audio signals outputted from the audio device to produce filtered audio signals, and wherein the filter circuit receives the divided DC voltage, wherein the filter circuit is connected to the output of the audio device. The switch circuit outputs controlling signals according to the divided DC voltage from the filter circuit. The amplifying circuit amplifies the filtered audio signals according to the controlling signals. An electronic device using the automatic gain control circuit is also provided.

Abstract: A measurement signal from a detector may have a complementary polarity. For example, an RF power detector may generate an output signal that decreases in magnitude in response to an increasing input signal. In one embodiment, the RF power detector may include a series of transconductance detector cells arranged to progressively turn off as the input signal becomes progressively larger.

Abstract: An electronic circuit includes an input terminal, a transimpedance amplifier connected to the input terminal and including an amplifier and a feedback resistor, a first time constant circuit smoothing an output from the transimpedance amplifier, a gain control circuit arranged between the input terminal and ground potential and controlling current flowing between the input terminal and the ground potential on the basis of the output from the first time constant circuit, and a safeguard circuit controlling the gain control circuit and blocking the current flowing between the input terminal and the ground potential, when a signal to be input into the input terminal is stopped.

Abstract: The output power of an RF power amplifier is controlled using a feedback loop including a differential integrator for controlling the amplifier's bias voltage. The gain of integration in the differential integrator is varied so as to compensate for variations in the derivative of the power amplifier output power versus the bias voltage.

Abstract: A control system may be selectively operated in open loop mode, for example, during data bursts. In a power control system, the transmitted power may be selectively held at a constant level, for example, at the end of a ramp period. The forward path gain of a control system may be varied in an inverse-function manner ahead of an integrator. The slope of a measurement signal from a detector may be made to have a complementary polarity.

Abstract: The present invention provides systems and methods for asymmetrically varying gain in a low noise amplifier. The amplifier includes a first stage amplifier, a plurality of second stage amplifiers coupled to the first stage amplifier, a comparator coupled to one of the second stage amplifiers, and a controller coupled to the comparator, the first stage amplifier, and the plurality of second stage amplifiers. The controller is configured to produce one or more gain control signals to change the gain of one of the first stage amplifier or the plurality of second stage amplifiers at a plurality of asymmetric rates so as to cause the power of the output signal to move toward one of the threshold values of the comparator. The rate of change of the gain is based on conditions including the gain of the first stage amplifier, gain of a second stage amplifier, and the sampled power level.

Abstract: This invention provides an electronic part for high frequency power amplification (RF power module) which will automatically perform the precharge level setting for proper output power at start of transmission without requiring the software process for precharging to run on the baseband IC, which can reduce the burden on users, namely, mobile phone manufacturers. Such electronic part configured to amplify RF transmit signals includes an output power control circuit which supplies an output power control voltage to a bias control circuit in a high frequency power amplifier circuit, based on an output power level directive signal. This electronic part is equipped with a precharge circuit which raises the output power control voltage to produce a predetermined level of output power, while detecting a current flowing through a final-stage power amplifying element, triggered by rise of a supply voltage at start of transmission.

Abstract: Circuitry and methods for improved amplifiers with large bandwidth and constant gain are provided. The combination of a synthetic inductive drain load and a bridged-T matching network provide amplifiers that can drive a substantial capacitive load with the above mentioned improvements over prior amplifiers. Additionally, circuits presented allow for improved rise time and insensitivity to temperature variations.

Abstract: An automatic level control circuit comprises a level detection circuit which detects attack detection to sense a detection level greater than a predetermined level and recovery detection to sense a detection level smaller than the predetermined level, and a gain control circuit which outputs a gain adjustment control signal to regulate a gain of an variable gain amplifier such that an output signal from the variable gain amplifier is set to a predetermined signal level. The gain control circuit generates multiple candidate signals to change the gain at different response speeds, and selectively outputs, as a gain adjustment control signal, one of the candidate signals capable of providing the smallest value as the gain. Therefore, even when the gain is rapidly reduced by the attack action against a short-duration large signal, the gain can be returned to its original state at an appropriate speed.

Abstract: An automatic level control circuit comprises a gain controllable amplifier, a comparing and outputting circuit which compares a level of an output signal from the gain controllable amplifier with a reference level and outputs a result of comparison as a comparison result signal; an output signal restricting circuit which restricts the comparison result signal obtained in a period between one zero crossing point and another zero crossing point of the input signal such that a portion of the comparison result signal obtained within a predetermined output time is output, and an attack detecting and outputting circuit which restricts an output signal from the comparing and outputting circuit to the portion of the comparison output signal obtained within the predetermined time when the comparison result signal is output over the predetermined output time and outputs the restricted comparison result signal as an attack detection output signal.

Abstract: An electronic circuit includes an input terminal, a transimpedance amplifier connected to the input terminal and including an amplifier and a feedback resistor, a first time constant circuit smoothing an output from the transimpedance amplifier, a gain control circuit arranged between the input terminal and ground potential and controlling current flowing between the input terminal and the ground potential on the basis of the output from the first time constant circuit, and a safeguard circuit controlling the gain control circuit and blocking the current flowing between the input terminal and the ground potential, when a signal to be input into the input terminal is stopped.

Abstract: The present invention relates to an AGC circuit, a AGC circuit gain control method, and a program for the AGC circuit gain control method, and may be applied to IC recorders, for example, as a portable recording/reproducing device, in order to ameliorate problems of listening to talk, music and the like during playback from IC recorders. In the invention, a signal level L1cyc is detected in units of the period of an input signal, and a recovery time constant r is switched on the basis of a decision as to the signal level L1cyc based on an average shift Lavg of the signal level L1cyc.

Abstract: Circuitry and methods for improved amplifiers with large bandwidth and constant gain are provided. The combination of a synthetic inductive drain load and a bridged-T matching network provide amplifiers that can drive a substantial capacitive load with the above mentioned improvements over prior amplifiers. Additionally, circuits presented allow for improved rise time and insensitivity to temperature variations.

Abstract: A two-stage amplifier includes a first stage and a second stage that are DC-connected through a coupling capacitor Cp. A charge pump generates a bias voltage Vp that is applied across the coupling capacitor Cp leads to maintain the time average of the voltage across said coupling capacitor constant.

Abstract: Circuitry and methods for improved amplifiers with large bandwidth and constant gain are provided. The combination of a synthetic inductive drain load and a bridged-T matching network provide amplifiers that can drive a substantial capacitive load with the above mentioned improvements over prior amplifiers. Additionally, circuits presented allow for improved rise time and insensitivity to temperature variations.

Abstract: Circuitry and methods for improved amplifiers with large bandwidth and constant gain are provided. The combination of a synthetic inductive drain load and a bridged-T matching network provide amplifiers that can drive a substantial capacitive load with the above mentioned improvements over prior amplifiers. Additionally, circuits presented allow for improved rise time and insensitivity to temperature variations.

Abstract: An automatic gain control circuit integrally fabricated on a semiconductor substrate. An AGC circuit 17 controls the gain of an intermediate-frequency amplifier circuit 15 so that the average level of the output signal (sound signal) of an AM detector 16 may be substantially constant. The AGC circuit 17 includes a time-constant circuit 100, which comprises a charging circuit for intermittently charging the capacitor and a discharging circuit for intermittently discharging the same. By this intermittent charging and discharging of the capacitor having a small capacitance, a large time constant is set.

Abstract: A voltage amplifying circuit (100) that may have a selectable gain has been disclosed. Voltage amplifying circuit (100) may include a voltage amplifier (2) and a gain changing unit (7). A gain changing unit (2) may be capable of changing at least one of: a capacitance between a signal input terminal (6) and an input terminal of a voltage amplifier, the capacitance between an input terminal of a voltage amplifier and a ground (or reference potential), and a capacitance between an input and an output terminal (3) of a voltage amplifier. In this way, a gain from a signal input terminal (6) to an output terminal (3) of a voltage amplifier of a voltage amplifying circuit (100) may be changed.

Abstract: A power amplifier driver (16) provides control voltage inputs to power amplifier (14) at terminal (OUT). An output power control loop is implemented through directional coupler (20) and power amplifier driver (16). Power amplifier driver (16) implements a loop integration function utilizing transconductance amplifiers (60, 62) to convert a detection signal (DET) and a reference signal (REF2) to current for summing at node 58. Transconductance amplifiers (70,72) convert the error voltage generated at node (34) and bias voltage (Vmin) to current for summing at node (36) for subsequent conversion back to voltage by resistor (74). The error voltage at node (36) is buffered (26) to provide adequate current drive at terminal (OUT).

Abstract: An apparatus and method is directed to a power amplifier control circuit that includes a bandwidth switching circuit. The power amplifier control circuit can be used in a GSM EDGE system for controlling the output power of a communication signal. The loop bandwidth of the power amplifier control circuit is high during ramp-up and ramp-down of the output power, and low during transmission of the communication signal. The power amplifier control circuit regulates the output power during power ramping, while preserving the amplitude modulation portion of the communication signal during transmission. The bandwidth switching circuit includes a pair of capacitance circuits that are arranged such that both capacitance circuits charge without affecting the loop bandwidth. The bandwidth switching circuit operates at high speeds associated with a GSM EDGE system, while avoiding transient glitches that may occur due to charging and discharging in the capacitance circuits.

Abstract: A variable gain amplifier device comprises a variable gain amplifier circuit which amplifies a difference between an input signal and a feedback signal to output an output signal, a feedback circuit which supplies the feedback signal to the variable gain amplifier circuit, and a controller which controls the variable gain amplifier circuit and the feedback circuit to decrease a cutoff frequency of the feedback circuit according to increase of a gain of the variable gain amplifier circuit or vice versa.

Abstract: Circuitry and methods for improved amplifiers with large bandwidth and constant gain-are provided. The combination of a synthetic inductive drain load and a bridged-T matching network provide amplifiers that can drive a substantial capacitive load with the above mentioned improvements over prior amplifiers. Additionally, circuits presented allow for improved rise time and insensitivity to temperature variations.

Abstract: In a gain control device for packet signal receiver, a variable gain amplifier amplifies an input signal with a gain corresponding to a control voltage applied thereto, and a power detector detects output power of the variable gain amplifier. A packet detection circuit detects a packet signal based on the detected output power. A control circuit outputs the control voltage variable with the detected output power, and the control voltage is provided for the amplifier. Thus high-speed gain control is performed immediately after the start of detection of the packet signal. When the elapsed time after the start of detection of the packet signal exceeds a predetermined time, a sample-hold circuit sample-and-holds the control voltage. This control voltage is provided for the amplifier up to the end of reception of the packet signal thereafter. Thus low-speed gain control is performed to provide stable power without distorting the signal wave.

Abstract: A system and method of processing received signals in an ultrasound imaging system is disclosed. In the system, the received signals are amplified by means of a gain controlled amplifier, and the gain of the amplifier is varied, by varying the load capacitance, as a function of depth (time) to compensate for the attenuation of ultrasonic energy at different depths within a patient's body.

Abstract: A two-stage amplifier includes a first stage and a second stage that are DC-connected through a coupling capacitor Cp. A charge pump generates a bias voltage Vp that is applied across the coupling capacitor Cp leads to maintain the time average of the voltage across said coupling capacitor constant.

Abstract: The invention relates to a device for transmitting radiofrequency signals using a power amplifier. The power amplifier is connected to a power regulation loop for regulating its gain in such a manner as to bring the output power level to a desired nominal level. The regulation loop acts on the bias voltage as a function of the output from the power amplifier. According to the invention, the device further comprises adjustment means such as an integrating RC circuit for supplying an additional voltage to the regulation loop in such a manner that the input signal to the loop is more responsive and less dependent on the active components of the power amplifier. The invention is particularly applicable in the field of mobile transmission.

Abstract: The invention relates to a variable gain and low noise amplifier for received signals in ultrasound or nuclear magnetic resonance imaging apparata. This variable gain and low noise amplifier comprises at least one amplifier unit having at least one input and at least one output and at least one feedback circuit which connects one of the output signals with a feedback input. The variable gain and low noise amplifier is characterized in that at least one feedback circuit comprises at least one capacitive divider.

Abstract: Method for operating an RF power amplifier (100; 200) with an approximately linear characteristic by adjusting at least one operating parameter of the amplifier or at least one active component of this amplifier, wherein a minimum collector or drain current of the active component or, respectively, an amplifier stage and the input signal level of the RF power amplifier are controlled in dependence on the quotient of harmonic power and useful-signal power of the amplifier output signal.

Abstract: The invention relates to a variable gain and low noise amplifier for received signals in ultrasound or nuclear magnetic resonance imaging apparata. This variable gain and low noise amplifier comprises at least one amplifier unit having at least one input and at least one output and at least one feedback circuit which connects one of the output signals with a feedback input. The variable gain and low noise amplifier is characterized in that at least one feedback circuit comprises at least one capacitive divider.

Abstract: The invention relates to a device for transmitting radiofrequency signals using a power amplifier. The power amplifier is connected to a power regulation loop for regulating its gain in such a manner as to bring the output power level to a desired nominal level. The regulation loop acts on the bias voltage as a function of the output from the power amplifier. According to the invention, the device further comprises adjustment means such as an integrating RC circuit for supplying an additional voltage to the regulation loop in such a manner that the input signal to the loop is more responsive and less dependent on the active components of the power amplifier. The invention is particularly applicable in the field of mobile transmission.

Abstract: A limiter circuit is provided for limiting the output from a comparing circuit so that the attenuating characteristic curve of an amplifying circuit 11 relative to a detected voltage Vo has an inflection point. Namely, since the limiter circuit serves to limit a difference voltage between the outputs from differential transistors, it reduces the sensitivity of the attenuating characteristic within a region from a high level signal to a middle level signal. Thus, the detected voltage Vo increases for acquiring the same attenuating amount so that the recovery time can be prolonged. Further, another limiter circuit is provided for fixing a detected voltage Vo at a prescribed DC voltage when the input signal exceeding a cover range for automatic level control is supplied to the input terminal. The limiter circuit operates to fix the output signal at a DC voltage VL when the input signal exceeds the cover range and enters the range where the level of the output signal starts to rise.

Abstract: A variable gain amplifier comprises a main amplifier circuit whose gain is controllable and which amplifies a difference signal between an input signal and a feedback signal, a feedback amplifier circuit whose gain is controllable and which amplifies an output signal of the main amplifier circuit, and a gain control circuit which complementarily control the gain of the main amplifier circuit and the gain of the feedback amplifier circuit.

Abstract: An automatic gain control system comprises a system input and a system output, detecting means adapted to convert an input signal into a signal level indication, which detecting means includes a rectifier and a 60 tap FIR filter with a Chebychev window, an AGC state machine coupled to receive said indication and output a gain level control signal, which state machine is adapted to adjust said gain level control signal when there is a signal present on the system input, a variable gain amplifier having an input coupled to receive the input signal from the system input, an output coupled to the system output, and a control input coupled to receive said gain level control signal for controlling the gain of said variable gain amplifier in order to keep the output signal level substantially constant as the level of the input signal varies.

Abstract: An AC-coupled pre-amplifier is provided for amplifying a signal received in a packet transmitted in burst mode. The pre-amplifier provides a fast time constant for a driven edge of a received signal and a slower time constant for a undriven edge of the received signal. The decay of the undriven edge is faster than the inter-packet time between two received packets. The dual response times, allows for the inter-packet time to be less than the longest string of constant data received in a packet.

Abstract: The invention provides an AC coupling circuit for receiving an output signal from a signal processing circuit having a first differential amplifier which has an inverting input and a non-inverting input, and for transmitting the output signal to a stage subsequent to the signal processing circuit as an AC signal. The first differential amplifier receives an input signal with a predetermined potential and a signal with a reference potential to differentially amplify the signals. The AC coupling circuit comprises a CR circuit including a resistor and a capacitor, and a feedback circuit. The feedback circuit includes a second differential amplifier for detecting a potential difference between a node of a stage previous to the CR circuit and a node of a stage subsequent to the CR circuit with reference to the potential of the node of the subsequent stage to the CR circuit to amplify the potential difference.