40results about How to "High loop gain" patented technology

A phase locked loop, PLL, is described with multiple parallel charge pumps that are selectively disabled as phase lock is approached. A lock detection circuit is described that enabled reference currents to be fed to the parallel charge pumps. The error signal from a phase detector is arranged as UP and a DOWN signals that are averaged in the lock detector. When the average error is large, all the reference currents feed the charge pumps that provide a high loop gain to reduce the lock time. As the lock becomes closer selective reference currents are disabled to reduce loop gain so that a smooth transition to lock is made. Selectively switching currents into a low pass filter that usually follows a charge pump in a PLL circuit automatically reduces switching noise by the operation of the low pass filter.

A fuzzy logic control arrangement is provided for an impedance match network of the type that is typically employed between a source of RF power at a given impedance, e.g., 50 ohms, and a non-linear load whose impedance can vary in magnitude and phase, e.g., an RF plasma. The fuzzy logic controller fuzzifies the phase and the magnitude error signals. The error signals are applied to a fuzzy logic interference function based on a number of fuzzy sets. The values of the error signals enjoy some degree of membership in one or more fuzzy sets. Fuzzy logic rules are applied to the phase and magnitude error signals. In a defuzzification stage, drive signal values are obtained for moving the tuning elements of the variable impedances. The drive signal values are weighted according to respective fuzzy inference functions for which the error signals enjoy membership. Then the weighted drive signal values are combined to produce output drive signals.

The invention is suitable for the field of integrated circuits and provides a power compensation circuit and a power supply chip of a switching power supply. The power compensation circuit comprises a sampling logic unit, a sampling retaining unit, an operational amplification unit, an energy accumulation unit, a comparator and a clamping unit, wherein the sampling logic unit is used for generating a sampling control signal according to a logic control signal; the sampling retaining unit is used for outputting a sampling processing unit according to the sampling control signal; the operational amplification unit is used for outputting an error amplification signal according to the sampling processing signal and a reference signal; the energy accumulation unit is used for charging and discharging according to the error amplification signal so as to adjust the voltage of the error amplification signal; the comparator is used for comparing a sampling voltage with the adjusted error amplification signal and outputting a compensation control signal so as to compensate peak current of a primary inductor and further compensate power; and the clamping unit is used for clamping the error compensation signal. In the invention, the peak current of the primary inductor is controlled through a negative feedback loop, and the loop gain is increased, thus the sampling time point is precisely optimized, and the output power is compensated on the basis that chip pins are not additionally increased and system efficiency is reduced.

The invention discloses a cascode fully integrated low-dropout linear voltage regulator circuit. According to the invention, a ascode current source is introduced to replace a conventional single transistor current source in a Cascoded Flipped Voltage Follower-Low-dropout (CAFVF-LDO) circuit, which increases the loop gain of the CAFVF-LDO circuit under heavy load condition; at the same time based on the structure features of the Cascode Current Source (CCS), a cascode compensation technology is introduced. Compared with the conventional CAFVF-LDO, the circuit of the invention, by means of a very small on chip compensation capacitor, realizes stable operation under a much lower load current, and a cascode compensation capacitor also expands the Unity-Gain-Frequency (UGF) of the LDO circuit under heavy load condition, and further improves load transient response of the circuit. The cascode fully integrated low-dropout linear voltage regulator circuit can be widely applied to the field of integrated circuits.

The invention discloses a linear voltage stabilizer with a low pressure differential and Sink and Source current capabilities. The voltage stabilizer comprises a reference voltage source, an error amplifier, two biasing circuits, a first N channel MOS (Metal Oxide Semiconductor) tube and a sample collecting and current limiting circuit of the first N channel MOS tube, a second N channel MOS tube and a sample collecting and current limiting circuit of the second N channel MOS tube and a compensating unit of the whole circuit. The voltage stabilizer works by the working principle that: the error amplifier detects the connecting way of the output resistor; when the output resistor is grounded, the loop controls the first N channel MOS tube to pass through the Source current; when the output resistor is connected with the power supply, the loop controls the second N channel MOS tube to pass through the Sink current. The linear voltage stabilizer disclosed by the invention is creative in designing concept, convenient to use and wider in application due to larger load capacity.

Disclosed are methods and circuits for providing a bandgap reference in an electronic circuit having a supply voltage and ground. The methods include steps for generating a bandgap reference current, mirroring the bandgap reference current, summing the mirrored currents, and modulating and outputting a bandgap reference voltage from the sum. Representative preferred embodiments are disclosed in which the methods of the invention are used in providing under-voltage protection and in providing a regulated output voltage. Circuits are disclosed for a bandgap reference voltage generator useful for providing a bandgap reference voltage in a circuit. A first current mirror for provides current from a supply voltage. A bandgap reference current circuit between the first current mirror and ground is configured for deriving a bandgap current proportional to absolute temperature. A second current mirror and control circuit are provided for summing the mirrored currents and modulating a bandgap reference voltage output. Preferred embodiments of the invention include a bandgap under-voltage detection circuit using a comparator and a voltage regulator circuit having a regulated voltage output capability.

An apparatus and method of automatic gain control (AGC) useful for a detector of a digital radio providing rapid settling and minimal distortion is described. The automatic gain control includes a plurality of modular AGC elements each having a unique bias. The AGC elements may also be switched from an open loop operating mode with a unique initial gain voltage to a closed loop operating mode. A matched filter is applied to the output of each of the AGC elements to filter out all but the signal constituents that match the reference symbol. The output of the matched filters having the greatest signal to noise ratio is the selected as the detector output. The output with the greatest signal to noise ratio corresponds to the output of the AGC element that has settled with the least distortion.

The invention discloses a high-linearity sigma-delta closed loop accelerometer interface circuit and belongs to the field of MEMS inertial components. The problems that an existing sigma-delta closed loop accelerometer interface circuit is low in loop gain, a sensitive structural weight block is large in displacement, so that charge voltage converting nonlinearity is increased, and an output signal harmonic component is enhanced are solved. A micro-machine accelerometer sensitive structure is connected with a phase compensation circuit, a first-level integrator circuit, a second-level integrator circuit, a summing circuit and a comparator through a charge detecting / correlated double sampling hold circuit. An output end of the comparator is connected with a weight block feedback end of the micro-machine accelerometer sensitive structure. The output end of the comparator outputs a system bit stream signal. Compared with a traditional feedback structure, system loop gain is greatly improved, static feedback force is increased, weight block displacement is reduced, nonlinearity of a signal detecting and processing circuit is lowered, and the performance of the sigma-delta closed loop accelerometer interface circuit is improved.

Disclosed are methods and circuits for providing a bandgap reference in an electronic circuit having a supply voltage and ground. The methods include steps for generating a bandgap reference current, mirroring the bandgap reference current, summing the mirrored currents, and modulating and outputting a bandgap reference voltage from the sum. Representative preferred embodiments are disclosed in which the methods of the invention are used in providing under-voltage protection and in providing a regulated output voltage. Circuits are disclosed for a bandgap reference voltage generator useful for providing a bandgap reference voltage in a circuit. A first current mirror for provides current from a supply voltage. A bandgap reference current circuit between the first current mirror and ground is configured for deriving a bandgap current proportional to absolute temperature. A second current mirror and control circuit are provided for summing the mirrored currents and modulating a bandgap reference voltage output. Preferred embodiments of the invention include a bandgap under-voltage detection circuit using a comparator and a voltage regulator circuit having a regulated voltage output capability.

Described herein are several configurations of Class-D audio amplifiers, including a single-ended and a bridge-tied load (BTL) configuration, in which voltage-mode control and average current-mode control circuitry in feedback loops can be included to control the outputs of the Class-D amplifier to reduce open-loop errors and maintain a relatively high loop gain over an expected audio frequency range. The average current-mode control circuitry monitors current through a resistor common to both a current flow into a positive terminal of a loudspeaker associated with the amplifier and a current flow into a negative terminal of the loudspeaker. The voltage-mode control circuitry works with the average current-mode control circuitry in controlling the output of the Class-D audio amplifier.

The invention discloses a low quiescent current off-chip capacitor-free LDO with a dynamic optimization power supply rejection ratio. An LDO circuit comprises an LDO main module and a PSR optimization module; the LDO main module is used for providing a stable output voltage when a load current or an input voltage changes; and the PSR optimization module injects a frequency-related compensation current into a grid electrode of a power tube in the LDO main module and is used for optimizing the intermediate-frequency PSR of the LDO. According to the low-quiescent-current off-chip capacitor-free LDO with the dynamic optimization power supply rejection ratio, a power tube copy tube is not needed, and the advantage of low quiescent current is achieved; and the feed-forward compensation current is dynamically adjusted by monitoring the working state of the power tube, so that the flexibility is higher.

A control system of a peak value current type cuk switch converter is characterized in that the system includes a cuk type switch power source power level circuit, a voltage loop control circuit, a current loop control circuit and a duty ratio generation circuit; the voltage loop control circuit acquires signals VEA_OUT through detecting error signals of output voltage Vo and reference voltage VREF; the current loop control circuit acquires Vc through detecting and adding power tube current VSEN_OUT and slope signals VRAMP together; the duty ratio generation circuit compares VEA_OUT with Vc and thus generates duty ratio signals for controlling the switching on and switching off of a power tube MN1 of a cuk type switch power source. The invention can provide comparatively high loop gain, can effectively improve system load modulation rate and a compensation network is simple and effective.

Disclosed are systems implementing an implicit Feed-Forward Compensated (FFC) op-amp, where the main FFC port is realized by the P-side of the CMOS input structure of the 2nd and 3rd stages of the op-amp, while the main signal path is through the N-side. According to some embodiments, to balance the relative strengths of the main path and feed-forward paths, the 2nd-stage NMOS input pair is split into two pairs, one is used to route the main path while the other is used for auxiliary FFC. The disclosed implicit FCC op-amp is unconditionally stable with adequate phase lead. According to some embodiments, the disclosed op-amp, which may be a wide-band op-amp, can be used in highly linear applications operative at intermediate frequency (IF), such as signal buffers for high-performance data converters or radio-frequency (RF) modulators and demodulators, continuous-time (CT) filters or sigma-delta data converters.

The invention discloses a driving method of a laser. A single chip microcomputer is adopted to control a PWM converter to realize adjustment of the working current of the laser; the adjustment is simple and convenient, the control efficiency is high, and the flexibility is greatly improved; working current change of the laser is collected by a sampling resistor; the collected current signal changes are converted into voltage signal changes; the voltage signal is amplified by an error amplifying circuit and then transmitted to the single chip microcomputer; the single chip microcomputer outputs a digital control signal to the error amplifying circuit according to the voltage signal input by the error amplifying circuit; the error amplifying circuit adjusts the output voltage and transmits to the PWM converter; and the PWM converter adjusts output duty ratio so as to adjust the working current of the whole laser. Meanwhile, the invention provides a driving circuit of the laser and an application of the driving circuit in a pump laser.

The invention provides a CMOS capacitor neutralization active mixer, and belongs to the field of mixers. The active mixer comprises a transconductance input stage, a switch mixing stage and an outputload stage, and received radio frequency voltage signals are converted into intermediate frequency voltage signals through the mixer to be output. According to the invention, two capacitor cross coupling circuit units are used in the transconductance input stage in an improved manner, a low noise index is generated, and the two capacitor cross coupling circuit units are connected through an NMOS / PMOS stacked structure, so that the power consumption of the circuit is effectively saved; the bandwidth is effectively enhanced by designing a passive matching network; capacitance neutralization techniques are used for compensating for source-drain electrode parasitic effect of transconductance input stages and loop gain of enhanced transconductance stages, so that the isolation degree and the linearity of the mixer are improved.

The present invention provides an optical transmitter that prevent the overshoot and undershoot appeared in the emission wavelength caused by the fluctuation of the temperature of the laser diode installed therein. The optical transmitter includes a TEC driver, and a master controller. The TEC driver, by comparing the monitored temperature with the target temperature, outputs the error signal to the master controller, which enables the LD-Driver only when the error signal continuously stays within a convergent range by a preset period.

The invention discloses a phase discriminator circuit applied to clock data recovery. The circuit is used for respectively carrying out phase discrimination on a random data signal and a random data delay signal by utilizing a clock signal, judging whether the rising edge of the clock signal is in the midpoint of the rising edges of the random data signal and the random data delay signal so as tooutput a phase advance or lag mark signal and finally realizing the clock data recovery and ensuring that the clock signal after circuit recovery is in an optimal sampling point relative to the recovered data signal; in addition, the phase discriminator performs phase discrimination on two data edges simultaneously by utilizing the clock edges, and the gain of the phase discriminator is two timesmore than that of the common phase discriminator, therefore the loop gain of a clock data recovery circuit is increased, the locking and capturing range is broadened, the locking time is shortened, and the performance of the clock data recovery circuit is improved.

The invention provides a PWM-based TEC driving circuit and a method for improving the driving ability of the driving circuit. The PWM-based TEC driving circuit comprises a laser, wherein the laser includes an NTC resistor and a TEC. The PWM-based TEC driving circuit is characterized in that the PWM-based TEC driving circuit further comprises an error amplification circuit which is in electric control connection with the NTC resistor and is used for converting the change of the resistance value of the NTC resistor caused by temperature change into the change of voltage signals and amplifying the change of voltage signals, a PWM driving circuit which is in electric control connection with the error amplification circuit and the TEC and receives the voltage signals of the error amplification circuit to control the TEC and make the same perform temperature adjustment. The invention also provides a method for improving the driving ability of the PWM-based TEC driving circuit.

The present invention provides an optical transmitter that prevent the overshoot and undershoot appeared in the emission wavelength caused by the fluctuation of the temperature of the laser diode installed therein. The optical transmitter includes a TEC driver, and a master controller. The TEC driver, by comparing the monitored temperature with the target temperature, outputs the error signal to the master controller, which enables the LD-Driver only when the error signal continuously stays within a convergent range by a preset period.

A self-oscillating amplifier system is disclosed. The system comprises a pulse modulator, a switching power amplification stage and a demodulation filter. Moreover, the system comprises a compensator including a forward filter which is a high order filter including a second order pole pair and a second order zero pair. Hereby it is possible to decrease the phase turn at low frequencies for better stability and increasing the gain of the control loop within the desired bandwidth.

Described herein are several configurations of Class-D audio amplifiers, including a single-ended and a bridge-tied load (BTL) configuration, in which voltage-mode control and average current-mode control circuitry in feedback loops can be included to control the outputs of the Class-D amplifier to reduce open-loop errors and maintain a relatively high loop gain over an expected audio frequency range. The average current-mode control circuitry monitors current through a resistor common to both a current flow into a positive terminal of a loudspeaker associated with the amplifier and a current flow into a negative terminal of the loudspeaker. The voltage-mode control circuitry works with the average current-mode control circuitry in controlling the output of the Class-D audio amplifier.

The invention discloses a wide voltage trans-impedance amplifier. The trans-impedance amplifier is suitable for the field of low-voltage radio frequency receivers and other low-voltage and wide-voltage analog circuits, current-to-voltage conversion is achieved, the trans-impedance amplifier monitors input voltage through a common-gate amplifier, trans-conductance enhancement is achieved on an input tube through a current mirror, and meanwhile high loop gain is guaranteed. Compared with a trans-impedance amplifier of a traditional structure, the power supply voltage of the structure is reducedby the magnitude of threshold voltage, and the structure can work under lower power supply voltage. The circuit has the characteristics of wide power supply range, low minimum working voltage, low input impedance, high output impedance and the like.

In a line driver an input current (IINN) feeds a node (K1) which is connected to an input on an amplifier (OTA1). A further input on the amplifier (OTA1) has a reference voltage (VSGND) applied to it. The amplifier (OTA1) controls a current source (MN1) which outputs an output current (IOUTN). A current / voltage converter (R1) is connected between the node (K1) and the current source (MN1). A voltage / current converter (R2) is connected between the current source (MN1) and a ground (VSS).

The amplifier according to the present invention serves to amplify an input signal to an output signal and includes a signal path and a negative feedback connection. The signal path includes a modulator which is suitable for receiving the input signal and for generating a switching signal in response to the received input signal. The signal path further includes a switched output stage, which is connected to a supply voltage, wherein the switched output stage contains a switch that is switched according to the switching signal generated by the modulator, wherein the switched output stage generates an output signal the amplitude of which depends on the supply voltage.

The invention relates to a low-dropout power supply ripple suppression linear voltage regulator, which is characterized by comprising a linear voltage stabilizer main body circuit and a power supply ripple suppression circuit, wherein the linear voltage stabilizer main body circuit is responsible for providing a stable direct-current output voltage and suppressing low-frequency disturbance of theoutput voltage, and the enhanced power supply ripple suppression circuit compensates for loop gain of medium and high frequency bands by introducing a self-bias current multiplexing common-gate amplifier at a load end. According to the low-dropout power supply ripple suppression linear voltage regulator, a rapid feedback loop is constructed at the load end, output voltage changes are dynamically monitored, and fluctuations of the output voltage is compensated by rapidly adjusting grid voltage of a driving tube.

The invention provides an X-band satellite-borne phase-locked receiver. The X-band satellite-borne phase-locked receiver comprises a receiving link front end, a main phase discriminator, a loop filter and a voltage-controlled oscillator and further comprises a loop gain control device, wherein the receiving link front end is used for inputting a received signal, performing down-conversion of the received signal according to a frequency conversion reference signal output by the voltage-controlled oscillator, and outputting an intermediate-frequency signal; the main phase discriminator is used for receiving the intermediate-frequency signal and the frequency conversion reference signal, performing phase discrimination of the intermediate-frequency signal according to the frequency conversion reference signal, and outputting a direct-current voltage signal and an alternating-current difference beat signal to the loop filter; the loop filter is used for removing the alternating-current difference beat signal by filtration and outputting the direct-current voltage signal to the voltage-controlled oscillator; the voltage-controlled oscillator is used for outputting the frequency conversion reference signal under the control of the direct-current voltage signal; and the loop gain control device is used for performing phase discrimination of the phase-shift intermediate-frequency signal according to the frequency conversion reference signal, and controlling the direct-current gain of the loop filter to be increased when phases are same. By means of the X-band satellite-borne phase-locked receiver disclosed by the invention, the problems that the nondeterminacy of the selective static frequency of the X-band phase-locked receiver is relatively high and the scanning time of a ground measurement and control station is relatively long in the existing aerospace vehicle can be solved.

The power supply is composed of operational amplification circuit (OAC) and power amplification circuit (PAC). The output end of OAC is connected to PAC. Output from complementary symmetry circuit of dual power supplies is adopted in PAC, which uses diode as bias circuit. Being connected to feedback resistance, the push pull amplification circuit is connected to the input end of OAC. Features are: high loop gain, small waveform distortion, capable of carrying out linear power amplification with high fidelity for inputted AC signal. Using AC inverse feedback to guarantee independence between outputted current and load, the invention is especially suitable to power supply with high requirement of waveform.

The invention discloses a cascode fully integrated low-dropout linear voltage regulator circuit. According to the invention, a ascode current source is introduced to replace a conventional single transistor current source in a Cascoded Flipped Voltage Follower-Low-dropout (CAFVF-LDO) circuit, which increases the loop gain of the CAFVF-LDO circuit under heavy load condition; at the same time based on the structure features of the Cascode Current Source (CCS), a cascode compensation technology is introduced. Compared with the conventional CAFVF-LDO, the circuit of the invention, by means of a very small on chip compensation capacitor, realizes stable operation under a much lower load current, and a cascode compensation capacitor also expands the Unity-Gain-Frequency (UGF) of the LDO circuit under heavy load condition, and further improves load transient response of the circuit. The cascode fully integrated low-dropout linear voltage regulator circuit can be widely applied to the field of integrated circuits.