Abstract: In an automatic level controlling circuit, an output from a full-wave rectifying circuit 12 is supplied to a first and a second time constant circuit. The first time constant circuit includes a first amplifier 22 and a capacitor 15. The second time constant circuit includes a second amplifier 23 and the capacitor 15. The first amplifier 22 operates when the output V1 from the full-wave rectifying circuit 12 is larger than a DC level VDC. In this configuration, the attack times when an input signal is switched from no signal into a middle level signal and when the input signal is switched from the middle signal into a high level signal can be set at optimum values, respectively.

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 power amplifier circuit for amplifying an input signal includes an amplifying transistor and a power detection circuit. The power detection circuit includes a circuit for generating a signal which is directly proportional to the power level in the amplifying transistor. This may-be accomplished by generating a voltage proportional to the square of a current in the amplifying transistor and then averaging that voltage. In this manner, a more accurate indication of the power level in the amplifying transistor is obtained.

Abstract: A method and arrangement for controlling the power of a transmission amplifier reliably within as wide a power band as possible, for a desired transmission power level which is less than a predetermined limit value. In the present invention, a portion of the power emitted from the transmission amplifier is output through a switching device in addition to the power which is output through a directional coupler, and is used to control the transmission amplifier.

Abstract: A circuit for controlling the characteristics of a power amplifier including first and second inputs, a first amplitude detection circuit for producing a first output signal indicative of the amplitude of an input signal received from the first input, and a second amplitude detection circuit for producing a second output signal indicative of the amplitude of an input signal received from the second input. The circuit also includes a phase detection circuit for producing a phase signal indicative of the relative phase between the input signals supplied to the first and second inputs, an amplitude control circuit for receiving the outputs of the first and second amplitude detection circuits and producing an amplitude control signal therefrom, and a phase control circuit for receiving the output of the phase detection circuit and producing a phase control signal therefrom.

Abstract: The present invention presents a closed loop system that utilizes a non-linear reference to control a power amplifier's output power in order to obtain a linear transfer function of dB per adjustment step of a reference input. The closed loop system demonstrates that each non-linear stage/step in an automatic gain control system can create a linear closed loop system when using a non-linear reference. The closed loop system of the present invention eliminates the need for a linearization circuit for the system's power detector. The closed loop system may be used with most power amplifiers when linear control in terms of dB vs. adjustment setting of the input reference signal is desired. Output power in terms of dBms can be accurately set in linear steps where power control over a wide dynamic range is desired.

Abstract: An circuit and method are provided for amplifying RF input signal to produce RF output signals with third-order intermodulation distortion products. The circuit and method use a feedback signal to control the bias voltage of the amplifier, such that the output third-order intermodulation distortion product increases monotonically with the RF input signal power. Specifically, the third-order intermodulation distortion product responds over a predetermined output power range by increasing three decibels in response to each one-decibel increase in input power.

Abstract: Circuits for continuously varying the gain control for a low noise amplifier (LNA) of a wireless receiver are described. The gain, input third order intercept point (IIP3) and noise figure (NF) of an LNA are continuously varied according to the received power levels, causing the receiver to utilize less current at different power levels. At high gain levels the IIP3and NF are at a minimum, while at low gain levels the IIP3and the NF are at a maximum. By continuously varying the gain of an LNA throughout the operational range, the present invention achieves wider dynamic range and higher power efficiency. According to one aspect, the present invention includes a power coupler and a power detector which are utilized to produce a rectified voltage which is proportional to the input power or output power of an LNA. The rectified voltage is utilized by a control circuit which produces a signal which controls the gain, IIP3and NF of the LNA.

Abstract: A temperature-compensated diode rectifier circuit is coupled to the outside of an HF amplifier (PA) to derive a rectified voltage (UD) from an HF output signal (RFOUT) with a rectifier input (IR) via a directional coupler (D-CO) with secondary connections (1, 2), and has a rectifier output (OR) for the rectified voltage (UD), a rectifier diode (D1), a charging capacitor (C1) and a ballast resistor (R2). To stabilize the rectified voltage against temperature influences, the rectifier input (IR) is connected to a d.c. input voltage (UIN), and a compensating diode (D2) is in series with the ballast resistor (R2), and a dropping resistor (R1) is in series with the rectifier diode (D1). According to the invention the rectifier diode (D1), the compensating diode (D2), the dropping resistor (R1), the ballast resistor (R2) and the directional coupler (D-CO) are connected to the d.c. input voltage (UIN) so that the voltage amplitude of the decoupled HF output signal (RFOUT) is added to the d.c. input voltage (UIN).

Abstract: A linearized traveling wave tube amplifier with average power limiter is disclosed. The device includes an average power limiter for the purpose of preventing a TWT from operating at output powers higher than the required operating point. The device includes a detector for dynamically producing a detector signal proportional to an average power of an input signal and substantially independent from a peak power of the input signal, and an attenuator, in communication with the detector and the amplifier, for dynamically attenuating the input signal according to the detector signal. The limiter allows the TWTs to be optimized for performance at the required operating point, resulting in higher efficiency, and eliminates the need to size the amplifier for a power level any larger than the required operating point which reduces the cost and complexity of the system.

Abstract: In an automatic level controlling circuit, an output from a full-wave rectifying circuit 12 is supplied to a first and a second time constant circuit. The first time constant circuit includes a first amplifier 22 and a capacitor 15. The second time constant circuit includes a second amplifier 23 and the capacitor 15. The first amplifier 22 operates when the output V1 from the full-wave rectifying circuit 12 is larger than a DC level VDC. In this configuration, the attack times when an input signal is switched from no signal into a middle level signal and when the input signal is switched from the middle signal into a high level signal can be set at optimum values, respectively.

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 first output stage outputs current to an output terminal via current-mirror circuits based on a voltage difference input to non-inverting and inverting terminals. A second output stage comprises current providing transistors connected with the current-mirror circuits of the first output stage in a current-mirror manner for providing current, and outputs the current to the output terminal via rectifying components and switches.

Abstract: RF power detectors having a linear variation in differential output with the output power in dBm of a power amplifier. The detectors include a rectifying diode sensing the peak RF signal coupled thereto. Additional circuitry adds additional incremental loads to the detector output at various increased power amplifier outputs to maintain a substantially linear variation in detector output with the output power in dBm of the power amplifier. The second output of the differential output of the detector is referenced to the same number of forward conduction diode voltage drops as the output from the rectifying diode, so that the differential output of the detector is substantially temperature independent A resonant circuit may be used to enhance the sensitivity of the detector circuit.

Abstract: A detector comprises a first diode for detecting a high-frequency signal applied to the detector, a bias unit for supplying a predetermined bias voltage to the first diode; a first resistor having an end connected to the bias unit and another end connected to the first diode, a second diode connected in series with the first diode and having a same characteristic as the first diode, a second resistor having an end connected to the second diode and another end connected to a ground, and a detected voltage output terminal directly connected to a junction between the first diode and the second diode. The sum of a detected voltage generated by the first diode and a DC offset voltage caused by the bias voltage appears at the detected voltage output terminal. The first resistor has a resistance value different from that of the second resistor, and those resistance values are set to compensate for variations in the detected voltage with temperature.

Abstract: A diode detector that is stable and linear over a wide range of variations in both temperature and power supply voltage and can be used to regulate a.c. signals produced by devices that are responsive to control signals includes a detector diode and a first resistor in series, a capacitor connected between the junction of first resistor and the detector diode and a reference potential, and a compensator diode and a second resistor in series with each other and with the detector diode and first resistor. An input a.c. signal is provided to a first terminal of the detector diode, and a rectified signal is provided at the junction of the detector diode, the first resistor, and the capacitor. The detector diode and the compensator diode have temperature coefficients that are substantially the same, and those diodes have the same polarities.

Abstract: A suitable power amplification path is selected from at least one amplification path in a power amplifier, according to at least a signal modulated in one modulation mode, to reduce the size and the efficiency of the power amplifier. The power amplifier in accordance with the present invention comprises a bias voltage control terminal, an output change-over switch, a non-linear amplification path, and a linear amplification path. The non-linear amplification path includes a variable gain amplifier whose gain is set at predetermined gain, and a linear amplifier and a non-linear amplifier which amplify the output of the variable gain amplifier by controlling the bias voltage thereof with the output of a bias voltage control circuit. In the linear amplification path, the bias voltage of the linear amplifier is set constant and the gain of the variable gain amplifier before the linear amplifier is adjusted by controlling the bias voltage thereof, whereby the output level of the power amplifier is controlled.

Abstract: A power amplifier system is used for numerous types of audio equipment, and prevents output distortion of the amplifier from deteriorating, under any condition, by controlling a voltage-controlled amplifier in response to fluctuation of an input signal and a power supply voltage. The power amplifier system includes a limiter that extracts a signal at a point of connection between a voltage amplifier and a power amplifier, converts the signal into a d.c. voltage with an integrating circuit after passing it through a voltage comparator, and varies the degree of amplification of a voltage control amplifier, so as to maintain an output voltage at a constant distortion ratio by application of a voltage limited according to an output level of the power amplifier.

Abstract: The invention relates to a method for transmitter power control and a control arrangement employed for transmitter power control. The control arrangement comprises a control element (1) controlled by a control signal, a sampling means (3) for taking samples of a signal from the control element (1). The control arrangement further comprises a detector (4), an adder (5) and a loop filter (6). The adder (5) and loop filter (6) form a controller for receiving a signal which is transmitted by the detector (4) and forms part of a feedback signal for controlling the control element (1). Between the input and output of the controller, the control arrangement comprises a parallel loop which, when being activated, keeps the feedback loop closed when the sample signal is outside the dynamic range of the detector (4). Keeping the feedback loop closed enables transmitter power control without discontinuities.

Abstract: A signal compressing apparatus is disclosed, which controls output signal in case of exceeding input signal to increase transmission efficiency and obtains stable output due to temperature compensation. The signal compressing apparatus includes an amplifier for amplifying an input signal applied through an input resistor connected to an input terminal at a constant gain, and a gain controller for rectifying only a specific band signal of output signals of the amplifier between the input terminal of the amplifier and an output terminal thereof, compensating temperature of the rectified signal, and outputting a control signal to allow the gain of the amplifier to be constant.

Abstract: The diode detector for detecting an RF signal has an input on which the RF signal is received, and an output on which a DC signal corresponding to the RF signal is emitted. The diode detector comprises a detector diode, a compensator diode, and a voltage divider configuration which, in addition to the detector diode and the compensator diode, comprises two resistors, and which form part of a DC path across which a DC bias, V.sub.batt, is applied. The input and output of the diode detector are connected to respective terminals of the detector diode in said DC path. A discharge capacitor ensures that the compensator diode does not receive the RF signal.

Abstract: An automatic microwave gain control device comprises a signal amplifier, a directional coupler coupled to one terminal of the signal amplifier for receiving a portion of an amplified microwave signal power, a microwave detection diode connected to one end of the directional coupler, a bias supply circuitry supplying an adjustable D.C. bias voltage to the microwave detection diode, a D.C. amplifier for amplifying a voltage derived from an addition of a microwave detection output voltage of the microwave detection diode and the bias voltage of the bias supply circuitry, and a variable attenuator provided at another side of the terminals of the signal amplifier, wherein the variable attenuator controls an output power outputted from an output terminal to be constant power by way of controlling a magnitude of attenuation of the signal at the another terminal of the signal amplifier according to an output voltage of the D.C. amplifier.

Abstract: An AGC circuit includes an amplifier, a first detector, a pulse generator, a second detector, a switching circuit, and a gain controller. The amplification factor of the amplifier for an input signal is controlled by a gain control voltage. The first detector detects the output level of the amplifier. The pulse generator generates a variable-width pulse signal on the basis of an output from the first detector. The second detector detects the presence/absence of an input signal. The switching circuit switches between an output from the pulse generator and an output from the first detector and outputs the switched output in accordance with a detection output from the second detector. The gain controller outputs the gain control voltage to the amplifier on the basis of an output from the switching circuit.

Abstract: A high-frequency power amplifier comprises a transistor for high-frequency power which operates and whose current-voltage characteristics greatly change when positive voltage is supplied on its input terminal, an input bias circuit, an output bias circuit, an input impedance matching circuit, an output impedance matching circuit, and a positive voltage generation circuit. The positive voltage generation circuit comprises a detection circuit which detects part of the high-frequency power which is entered to or outputted from the transistor for high-frequency power, a rectification circuit which rectifies the part of the high-frequency power outputted from the detection circuit and outputs pulsating positive voltage, and a smoothing circuit which smoothes the pulsating positive voltage outputted from the rectification circuit and outputs positive voltage.

Abstract: A monolithic RF amplifier circuit (10) suitable for use in the 0.8-2 GHz frequency range comprises, on-chip (12'), a gateable oscillator (24) running at about 2-5 times the amplifier input frequency or higher, coupled to a rectifier (30) and a low pass filter (34) for producing a DC signal which is fed via a bias/gain control circuit (46) to a bias/gain inputs (56, 58) of one or more amplification stages (60, 62) (e.g. GaAs FET) to provide bias therefore to ensure safe operation, and a priority control circuit (42) responsive to the bias. The priority control circuit (42) operates a power switch (18) that couples the amplification stages (60,62) to a power supply, only when bias is present on their bias/gain inputs (56,58) This protects the amplification stages (60,62) against overcurrent operation. A separate external port (68) to the bias/gain control circuit (46) adjusts the magnitude of the bias to permit amplifier gain and power output to be adjusted.

Abstract: An envelope level of an output of a variable gain power amplifier is detected by a detector. An envelope level of an output of the variable gain power amplifier detected by the detector and a waveform of a reference signal which is generated from a reference signal generator are compared. A gain of the variable gain power amplifier is controlled in accordance with a comparison output. Upon leading of a transmission output, the reference signal is raised from a grounding level to a rest value of the detector or more and is maintained at a value higher than the rest value of the detector. After the reference signal enters a response range of a negative feedback loop, it is smoothly raised along a cosine square wave. Upon trailing of the transmission output, the reference signal is smoothly reduced to a value near the rest value of the detector along a cosine square wave and is maintained at a value near the rest value of the detector.

Abstract: A detector for a portable telephone or the like samples RF transmit power, detects the sampled signal using a Schottky diode and uses a logarithmic amplifier to apply a compressive function to the post-detection signal. The compressive function emphasizes power level changes at the low end of the transmission spectrum and de-emphasizes power level changes at the high end of the transmission spectrum. In this way, the range of detected powers required to be processed by subsequent circuitry is reduced, thereby simplifying the design of the circuit. To improve stability of the detector with respect to temperature fluctuations, the semiconductor element in the amplifier which provides its logarithmic characteristics is temperature-compensated, as is the detector diode.

Abstract: A circuit for automatically limiting fluctuations in the output power level of a transmitter by providing a feedback control signal which is based on the output power level. An RF signal (100) is input to a terminal of the RF detector (200). When the RF signal (100) is more negative than a bias voltage (209), a capacitor (208) begins charging. When the RF signal (100) becomes more positive than the bias voltage (209), the voltage in the charged capacitor (208) is added to the RF signal (100) and then averaged by the capacitors (214 and 206) to form voltage VE. Voltage VE in conjunction with the current setting circuitry (230) establishes a tail current (235) which is comprised of transistor (216) current (225) and the current from the RF detector (200). The tail current (235) tends to remain constant whereas the transistor current (225) is responsive to power changes in the RF signal (100) and represents the difference between the output power level of the RF power amplifier and the specified reference (110).

Abstract: A method for obtaining a rectified signal from a first alternating current signal. The method includes the step of inputting the first alternating current signal into a variable gain amplifier to obtain a second alternating current signal. The second alternating current signal has a substantially constant peak-to-peak voltage irrespective of a power level of the first alternating current signal. The method further includes the step of rectifying the second alternating current signal, using a power detector circuit, to obtain the rectified signal, whereby a direct current level of the rectified signal is substantially proportional to the power level of the first alternating current irrespective of the power level of the first alternating current. The rectified signal may then be employed in, for example, a feedback control circuit to control the amount of power output by an RF signal source.

Abstract: A circuit for controlling the output level of a power amplifier is disclosed. A current comparator (230) compares a reference current with a sensed current which is representative of the power amplifier current state. The reference current is used not only for comparison with the sensed current but also for setting the power amplifier (104). The current comparator (230) provides an output, based on the comparison, that is coupled to the power amplifier so that the power amplifier current is maintained at an optimum level for minimizing temperature dependent variations and substantially leveling the power of the power amplifier.

Abstract: The object of the invention is a circuit for monitoring the power of a transmitter amplifier. In the solution according to the invention, the detected DC voltage level (V.sub.det) corresponding to the output power is compressed at high output levels by using as the coupling capacitance a capacitance diode (7) such that the capacitance of this component, and thereby the tightness of the coupling, diminishes as the detected voltage level increases. The invention can be employed, for example, in the power control of a mobile phone's transmitter.

Abstract: A compressor which is capable of compressing an input signal having an extremely large magnitude, without the signal being distorted and without the necessity of a additional circuit element such as an automatic level controller external thereto. The compressor includes a summing amplifier, a full-wave rectifier, an active limiter, and a gain controller. The summing amplifier compresses an input signal and produces a compressed output signal which is a compressed version of the input signal. The full-wave rectifier full-wave rectifies the compressed output signal and converts the rectified compressed output signal to a DC voltage output, and converts the DC voltage output to a first DC output. The active limiter compares the DC voltage output with a prescribed limit voltage, and is only enabled when the DC voltage output is greater than the limit voltage to produce a second DC output which is proportional to the difference between the DC voltage output and the limit voltage.

Abstract: Control circuitry for maintaining the magnitude of an RF signal from an RF signal amplifier at a predetermined level includes a detector which is supplied with a signal indicative of the power level of the output from the amplifier and outputs a signal which is dependant upon the input signal. A detector (100) is provided with a negative feedback loop (200) which supplies a biasing voltage Vb to the input of the detector, whereby the biasing voltage Vb decreases if the magnitude of the signal (P) input and hence the output signal (Vr), increases, thus serving to decrease the output voltage (Vr), and vice versa. This has the advantage of increasing the dynamic range of the detector.

Abstract: An amplifying circuit with a small current consumption which is used for a portable radio, personal stereo systems or the like. The operating current of a differential amplifier, which is the main component of the amplifying circuit, is controlled by a first current circuit, which is a fixed constant-current source, and a second current circuit, which is a variable current source. The current of the second current circuit is controlled by an input audio signal with the voltage subjected to full-wave rectification. As a result, when the amplitude of the input signal is small, only a slight operating current is consumed by the first current circuit, thereby saving electricity. On the other hand, when the amplitude of an input audio signal is large, the current of the second current circuit also increases therewith, so that the amplifier flows a sufficiently large output current.

Abstract: A circuit for providing DC bias voltage to an RF power amplifier transistor where the DC bias voltage is derived from the RF input signal.

Abstract: A compressor with a DC bias control circuit is provided. The DC bias control circuit provides a predetermined DC current to a variable gain stage of the compressor circuit such that when the input signal to the compressor is substantially equal to zero, the variable gain stage is biased by the DC current and provides a DC feedback path for the compressor.

Abstract: The invention provides an amplifier having a feed-back path into which either of two different value resistances may be switched in dependance upon the level of the amplifier output.

Abstract: A circuit for automatically controlling the gain-bandwidth product of operation amplifiers, where gain-bandwidth product (G*B) of one of the amplifiers placed on the same chip as the amplifiers to be controlled is measured and the resulting signal is used to control through a bias circuit the gain-bandwidth products of all the amplifiers, the value of these products being presettable through the frequency of a control signal sent to the circuit input. The reference amplifier is highly compensated for and placed in the configuration of voltage follower.

Abstract: A controlled-output amplifier is provided whose output power level may be set to any of a number of predetermined levels and maintained substantially constant. The amplifier includes a detector which senses the output power level and produces a signal indicative of the magnitude thereof. The detector includes a single detector diode which may be biased to any of a number of preselected bias states by a bias control unit. The bias control unit increases the dynamic range of the detector diode while eliminating the need for a conventional temperature compensation diode.

Abstract: In a varactor diode tunable receiver supplied with operating current from batteries, the invention proposes to insert a blocking diode between the supply terminal of the playback amplifier and the input of the stabilizing circuit producing a stabilized tuning supply voltage for the varactor diodes, and to arrange a storage capacitor of suitable capacity in parallel with the input of the stabilizing circuit. This measure prevents the receiver from becoming detuned during voltage changes on the battery caused by the high modulation peaks of the playback amplifier. The battery can be used until the intended point of complete discharge is reached, without any considerable detunings of the receiver having to be feared.

Abstract: Circuitry for compensating for the effects of changes in ambient temperature on an automatic gain control arrangement in a missile-borne receiver is shown to include an operational amplifier responsive only to the level of the output signal from an automatic gain detector and amplifier, such end being effected by using temperature sensitive elements in the input and feedback circuits of the operational amplifier.

Abstract: A fast-attack circuit is employed in an A.C. amplifier automatic gain control circuit to temporarily apply a D.C. gain control signal immediately to the amplifier circuit in response to a sudden signal increase in excess of a predetermined threshold level to avoid the problems of over-attack and pinch-down which might otherwise arise during the period required for the AGC loop to achieve stabilized control following the inception of the signal increase.