90results about "Limiting amplitude using diodes" patented technology

A preamplifier having extremely high input impedance amplifies the electrical signal output from an electret condenser microphone (ECM) without suffering from the effects of a DC leakage current at the input. The preamplifier circuit includes a pair of cross-coupled PN junction diodes setting the input impedance, a PMOS device, and a load resistor configured similarly to a conventional preamplifier. A capacitor is placed between the input and the cross-coupled diodes such that a DC path no longer exists to bias the cross-coupled diodes. Therefore, leakage currents are prevented from upsetting the DC operating point of the preamplifier and biasing the cross-coupled diodes. Consequently, small signal gain distortion, excessive demodulation products and increased noise can be avoided.

A circuit and method provides for the protection of transducers from over excursion, particularly for the protection of transducers for audio loudspeakers. A frequency dependent excursion limiter circuit has an initial summing stage followed by a shaping filter stage. A clamping function is provided at the summing stage, or at a separate stage between the summing stage and the shaping filter stage, for clamping the driving signal at a predetermined maximum voltage if the driving signal exceeds the predetermined maximum voltage level. The shaping filter stage provides a frequency response shaping function based on a predetermined frequency response shaping criteria which is related to the frequency dependent excursion limits of the transducers being protected from mechanical overload. An inverse shaping filter function is provided at the initial summing stage by providing feedback from the shaping filter stage, thus eliminating the need for a separate inverse shaping filter circuit before clamping. The inverse shaping filter function allows low level signals below clamping to pass through the circuit unaffected.

A frequency dependent excursion limiter circuit is also provided in the closed loop circuit of servo feedback system for protecting transducers in a servo feedback system from over excursion.

A system for limiting audio output which in one embodiment includes an audio source, headphones coupled to the audio source, and a limiting circuit coupled to the headphones thereby reducing the power output at the headphones to a safe hearing level. The limiting circuit in one embodiment is integrated into the headphones and can not be disabled.

The invention discloses a low-cost, low-power consumption and high-performance automatic Q value adjustment amplitude limiting circuit, which comprises a rectification filter unit, a voltage detection unit and a drain unit, wherein the rectification filter circuit samples antenna voltage, and performs shaping processing to form sampled voltage VLM; the voltage detection unit compares the sampled voltage VLM with set internal reference voltage to obtain a drain control signal VC1; and the drain unit controls the current of a low-impedance path from an antenna to the ground according to the drain control signal VC1. The rectification filter unit of the circuit samples the voltage at the two ends of the antenna by utilizing a sampling diode and a sampling capacitor, the introduction of the sampling diode is favorable for reducing the influence of the amplitude limiting circuit on antenna resonance, and the adoption of the sampling capacitor greatly reduces pulse noises produced when the amplitude limiting circuit works; and a voltage division diode of the voltage detection unit adopts a diode connection method for P-channel metal oxide semiconductor (PMOS) transistors, and by the method, a territory area can be reduced and the influence of bulk effects on the circuit can be eliminated.

The invention discloses a gallium arsenide (GaAs) PIN tube limiter monolithic circuit with microwave high power and low clipping level, which adopts three-level structure design, wherein the first level adopts the geminate transistor structure of six same GaAs PIN diodes, wherein the cathodes and the anodes of three GaAs PIN diodes are connected in series, the anodes are connected with a microwave signal transmission line, the cathodes are grounded, the cathodes and the anodes of the other three GaAs PIN diodes are connected in series, the cathodes are connected with the microwave signal transmission line, and the anodes are grounded; the second level and the third level adopt the transistor structure of the same diode, wherein the anode of one GaAs PIN diode is connected with the microwave signal transmission line, and the cathode thereof is grounded, the cathode of the other GaAs PIN diode is connected with the microwave signal transmission line, and the anode thereof is grounded. The invention has the advantages that the signal of the monolithic limiter has large signal-passing power and small leaked level and is convenient to apply. The invention can be obtained in volume production by a three-inch GaAs PIN diode monolithic technology and has good consistency and low cost.

A power limiter for limiting power of high frequency signals at an input to a receiver comprises a plurality of transmission line sections connected in succession. Each section has a series inductance coupling an input to an output of the section, and a shunt capacitance constituted by capacitance of at least one pair of oppositely-poled Schottky diodes coupled at the output of the section to limit voltage of the signal at the output. Individual diodes can be replaced by series-connected diodes, or by an array of parallel and series-connected diodes, in different sections for improved performance of the limiter. The limiter can be integrated with a GaAs low noise amplifier of the receiver.

A radio frequency power amplifier and corresponding methods are arranged and configured to drive or provide a radio frequency signal to a resonant load. The amplifier includes a radio frequency switching stage with an output that is coupled to a resonant circuit and configured to provide an output signal with amplitude modulation corresponding to amplitude modulation of an input signal when powered from a fixed voltage power supply and a feedback control system coupled to the input signal and the output signal. The feedback control system includes a sequencer configured to provide a sequencer output that is used to drive the radio frequency switching stage, where the sequencer output has an OFF state that begins at a variable time corresponding to the input and output signal.

In a portable radio transceiver, a power amplifier system includes a saturation detector that detects power amplifier saturation in response to duty cycle of the amplifier transistor collector voltage waveform. The saturation detection output signal can be used by a power control circuit to back off or reduce the amplification level of the power amplifier to avoid power amplifier control loop saturation.

A limiter circuit passes, from input signal voltages, only a signal voltage component contained in a range between the input signal voltage and the upper limit signal voltage by the switching action of a pair of transistors. In this circuit, since the pair of transistors compare the input signal voltage and a threshold signal voltage and switch lines, simultaneously, there is no influence of the propagation delay speed and no switching noise occurs when switching lines. Moreover, since no diode is used, a high-speed limiter circuit can be fabricated.

The invention relates to a wide-band low-temperature radio-frequency microwave power amplitude limiter with extremely-low insertion loss and belongs to the technical field of audio-frequency microwave power amplitude limiters. The amplitude limiter comprises four Pin amplitude-limiting diodes, two radio-frequency microwave blocking capacitors C1 and C2 and a quarter-wavelength micro-strip line, wherein the two capacitors are respectively connected with a radio-frequency microwave input-output end; the four Pin amplitude-limiting diodes are respectively connected inversely to form two groups of Pin amplitude-limiting diode pairs; the end I of the first group of Pin amplitude-limiting diode pair is connected with the end I of the quarter-wavelength micro-strip line and the end II of the capacitor C1, the end II of the Pin amplitude-limiting diode pair is connected with the ground; the end I of the second group of Pin amplitude-limiting diode pair is connected with the end II of the quarter-wavelength micro-strip line and the end I of the capacitor C2, and the end II of the Pin amplitude-limiting diode pair is connected with the ground. The amplitude limiter has an ultra-wide working band and extremely-low leakage potential, can be used for protecting a high-temperature super-conduction filter system working under a low-temperature vacuum environment from being burned out by strong signals.

The present invention relates to an electromagnetic signal power limiter and its design method. The power limiter for an electromagnetic signal includes at least one transmission line for the signal. The transmission line is made up of a number of passive micro-diodes with ballistic electron transport. The micro-diodes are distributed on the transmission line, and are implemented in a controlled atmosphere. The invention applies notably to radiofrequency or hyperfrequency waves received by detection and communication devices.

A radio frequency power amplifier and corresponding method is arranged and configured to drive a resonant load. The radio frequency power amplifier includes a radio frequency switching stage with an output that is coupled to a resonant circuit. The switching stage is configured to provide an output signal with amplitude modulation corresponding to amplitude modulation of an input signal when powered from a fixed voltage power supply. The amplifier further includes a feedback control system coupled to the input signal and the output signal, where the feedback control system includes a sequencer configured to provide a sequencer output that is used to drive the radio frequency switching stage. The amplifier also includes an amplitude control system coupled to the output of the radio frequency switching stage and configured to limit an amplitude of the output signal and in some embodiments a power recovery system.

The invention provides a novel broadband power limiter having improved frequency characteristics and power capacity, suitable for use with GaAs low-noise amplifier circuits. The power limiter includes a shunt diode circuit and two impedance transformers. The first transformer is a step-down impedance transformer connected between the shunt diode circuit and the input to the limiter, and the second transformer is a step-up impedance transformer connected between the shunt diode circuit and the output of the limiter. The invention further provides a method for limiting the power of an input signal, comprising the steps of: transforming the input signal from the input impedance to an intermediate impedance; shunting a portion of the input signal to ground; and transforming a remaining portion of the input signal from the intermediate impedance to an output impedance. The invention further provides a novel impedance transformer suitable for use in the broadband power limiter and a method for providing such an impedance transformer.

A stacked diode limiter, which can suppress and eliminate a malicious high-power electromagnetic pulse signal and an Intentional Electromagnetic Interference (IEMI) signal that are input to the antenna line of a wireless system and that include a communication service frequency component having a power of several kW or more, includes a stacked diode unit including one or more diode stack parts formed on a center electrode of a coaxial line formed between an input connector and an output connector, each diode stack part being configured such that a plurality of diodes are arranged in series and stacked on top of one another, and an impedance matching unit for configuring dielectrics between the connectors and the coaxial line as heterogeneous dielectrics and matching impedances between the connectors and the coaxial line.

The invention relates to an electronic device comprising an RF-LDMOS transistor (1) and a protection circuit (2) for the RF-LDMOS transistor. The protection circuit (2) comprises: i) an input terminal (Ni) coupled to a drain terminal (Drn) of the RF-LDMOS transistor (1); ii) a clipping node (Nc); iii) a clipping circuit (3) coupled to the clipping node (Nc) for substantially keeping the voltage on the clipping node (Nc) below a predefined reference voltage, wherein the predefined reference voltage is designed to be larger than the operation voltage on the drain terminal (Drn) and lower than a trigger voltage of a parasitic bipolar transistor (100) that is inherently present in the RF-LDMOS transistor; iv) a capacitance (Ct) coupled between the clipping node (Nc) and a further reference voltage terminal (Gnd), and v) a rectifying element (D1, D2) connected with its anode terminal to the input terminal (Ni) and with its cathode terminal to the clipping node (Nc). The invention provides an RF-LDMOS transistor having an improved RF ruggedness, while not, or at least to a much lesser extent, compromising the RF performance of the RF-LDMOS transistor.

A circuit for voltage limitation is provided in a transponder with a resonant circuit, which comprises at least one inductor, a capacitor, a depletion layer component with an input, output, and a control input, a first resonant circuit terminal, which is connected to the input of the depletion layer element, and a second resonant circuit terminal, which is connected to the output of the depletion layer element, whereby there is a connection between the control input of the depletion layer component and the first resonant circuit terminal and the second resonant circuit terminal. A method for voltage limitation in a transponder is provided, whereby for voltage limitation in the transmitting and receiving resonant circuit, the control terminal of the depletion layer element is driven by the voltage of the first and second resonant circuit terminal.

A limiting circuit includes an input transconductance stage, an output transconductance stage, a feedback transconductance stage, first and second resistive loads, and a level limiting circuit. The input transconductance stage is operably coupled to convert an input voltage signal into an input current signal. The first resistive load is operably coupled to convert the input current signal and a feedback current signal into an intermediate output voltage signal. The output transconductance stage is operably coupled to convert the intermediate output voltage signal into an output current signal. The second resistive load is operably coupled to convert the output current signal into an output voltage signal. The feedback transconductance stage is operably coupled to produce the feedback current signal based on the output voltage signal. The level limiting module is operably coupled to limit at least one voltage level of the feedback transconductance stage.

Provided is a feedback amplifier. The feedback amplifier includes: an amplification circuit unit amplifying a bust packet signal inputted from an input terminal and outputting the amplified voltage to an output terminal; a feedback circuit unit disposed between the input terminal and the output terminal and controlling whether to apply a fixed resistance value to a signal outputted to the output terminal; a packet signal detection unit detecting a peak value of a bust packet signal from the output terminal and controlling whether to apply the fixed resistance value; and a bias circuit unit generating a bias voltage, wherein the feedback circuit unit determines a feedback resistance value to change the fixed resistance value in response to at least one control signal and adjusts a gain by receiving the bias voltage.

An RF power limiter and ESD protection circuit has a set of two CMOS FETs each configured to perform a diode function with a defined forward voltage and arranged in an anti-parallel configuration and coupled between the input terminal and the ground terminal. When an RF signal is applied symmetrically to the input terminal and ground terminal it becomes symmetrically attenuated when the signal level exceeds the defined forward voltage of the diode configured CMOS FETs. In the ESD protection mode one of the CMOS FETs acts as a grounded gate NMOS transistor with SCR action to provide for mitigation of voltage and current over-stress of transistors utilized in RF transceiver circuits. Generally, the circuit architectures allow input power levels to be limited to an extent that reliable operation can be maintained.

The invention provides an L-frequency band miniature chip type high-power amplitude limiter. The limiter comprises a high-thermal-conductivity high-frequency microwave printed circuit substrate, the high-thermal-conductivity high-frequency microwave printed circuit substrate is provided with the components of a coupling circuit which is used for carrying out power coupling on an input signal; a detection circuit which is used for carrying out power detection on the coupling signal; a direct-current bias circuit which is used for carrying out accelerated response on the amplitude limiting circuit, a high-power amplitude limiting circuit which is used for carrying out amplitude limiting on an input high-power signal, an impedance matching circuit A and an impedance matching circuit B for carrying out standing wave improvement on each element of the amplitude limiter, and a high-isolation amplitude limiting circuit for carrying out deep amplitude limiting on an output signal. The printedcircuit substrate adopts a ceramic printed circuit board, the purposes of high heat dissipation and small size of the amplitude limiter are achieved through the characteristics of the ceramic printedcircuit board and the dual-purpose mode of one board, the defects of small passing power and low response speed are overcome through combined connection between circuits, and the amplitude limiter with super power is achieved by combining the ceramic printed circuit board and the miniature sheet type size limiter on the miniature substrate.

a limiting amplifier with a power detection circuit (100) comprises an amplification section having a plurality of amplification inverters (INV1-INVn+1), a detection inverter (INV0) taking in and inverting an output potential of any of the amplification inverters, a diode (170) having an anode connected to an output of the detection inverter, and a detection resister (180) and a capacitor (190) connected in parallel between a cathode of the diode and a ground line. The output voltage of the inverter (INV0) is not reduced by a schottky current and, therefore, an output potential of the inverters INVn-1 is sufficiently amplified and the precise power detection is performed even if an amplitude of an input signal is high.

The invention discloses a microwave absorption type limiter. The microwave absorption type limiter comprises a microwave signal transmission line and a first capacitor connected on the microwave signal transmission line in series, and further comprises a coupling detection network and an amplitude limiting network which are connected with the microwave signal transmission line, wherein the first capacitor, the coupling detection network and the amplitude limiting network are orderly arranged between an input end and an output end of the microwave signal transmission line, a PIN amplitude limiting diode is arranged in the amplitude limiting network, the coupling detection network outputs a direct current signal, and the direct current signal is used for controlling on or off of the PIN amplitude limiting diode. In the microwave absorption type limiter provided by the invention, a 3dB electric bridge used in the conventional absorption type limiter is not used, thus, electric bridge losscan be avoided, and volume loss also can be reduced.

In an oscillator, a FET, an output matching circuit having a diode, an LC series resonant circuit having a capacitor and an inductor, a transmission line, and a source inductor are arranged on one surface of a substrate consisting of a semiconductor material. The source of the FET is grounded through a source inductor. The drain of the FET is connected to the anode of the diode of the output matching circuit through a transmission line. The FET amplifies a high-frequency signal input to the gate, and outputs the high-frequency signal from the drain to an output matching circuit. The diode regulates an oscillation power.