154 results about "Open-loop gain" patented technology

A polar-loop wireless communication apparatus includes, on a forward path between an amplitude detector and a power amplifier which constitute an amplitude control loop, a variable gain amplifier and a switch to change characteristics of a loop filter to output a frequency bandwidth of the amplitude control loop to an order less than an order for normal operation. The system is operated with the characteristics set to the lower order to measure outputs from the power amplifier to calibrate the output power of the power transmitter, and the register is operated with the characteristics set to the higher order to measure the open loop gain of the amplitude control. According to results of the calculation, data to correct gain characteristics of the variable gain amplifier with respect to an output control signal is stored in a nonvolatile memory of a baseband circuit.

A telephonic handset comprises an active noise reduction (ANR) system. The ANR system comprises a reference microphone and an IIR filter. The IIR filter is receivingly coupled to the reference microphone with respect to noise reference signals, and it is transmittingly coupled to the receiver transducing element of the handset. The ANR system is configured as a fixed feed-forward noise cancellation system. Preferably, the IIR filter has a transfer function derived, in part, from the open-loop gain of a feedback noise cancellation system.In specific embodiments of the invention, the noise reference microphone is situated so as to sample the ambient noise field near the front face of the receiver, but without directly sampling the noise field on the front face.

The present invention comprises a method and apparatus for continuously, controlling a gain of an amplifier circuit while switching between open-loop and closed-loop power control. A control circuit controls the gain of the amplifier circuit during open-loop and closed-loop power control modes based on selected references. Before the switch from open-loop to closed-loop power control, the control circuit determines a closed-loop reference based on a power measured at the amplifier circuit output before the switch. After the switch, the control circuit controls the gain of the amplifier circuit based on the determined closed-loop reference. Before switching from closed-loop to open-loop power control, the control circuit generates a difference between a current open-loop reference and a previous open-loop reference. After the switch, the control circuit controls the gain of the amplifier circuit based on an open-loop gain control signal generated by applying the difference to a previous closed-loop gain control signal.

The operating frequency of a ballast is sufficiently far from resonance that, when a compact fluorescent lamp is dimmed to about one percent light output level, the ballast is operating with an open loop gain below a predetermined level, such as, for example, 15, and is operating with an output impedance greater than a predetermined level, such as, for example, the absolute value of the maximum negative incremental impedance of the lamp, and more preferably, greater than twice the absolute value of the maximum negative incremental impedance of the lamp. By changing the frequency to 85 kHz from 80 kHz, for example, the gain is maintained about the same whether the light output is at five percent or one percent, for example. This provides a stable control loop. In this manner, compact fluorescent lamps can be dimmed below about one percent light output, without dropping out and without observable flicker.

A polar-loop wireless communication apparatus includes, on a forward path between an amplitude detector and a power amplifier which constitute an amplitude control loop, a variable gain amplifier and a switch to change characteristics of a loop filter to output a frequency bandwidth of the amplitude control loop to an order less than an order for normal operation. The system is operated with the characteristics set to the lower order to measure outputs from the power amplifier to calibrate the output power of the power transmitter, and the register is operated with the characteristics set to the higher order to measure the open loop gain of the amplitude control. According to results of the calculation, data to correct gain characteristics of the variable gain amplifier with respect to an output control signal is stored in a nonvolatile memory of a baseband circuit.

The invention belongs to the technical field of controlling of power converters of driving motors, and relates to a current control method for improving the output torque of a permanent magnet synchronous motor overmodulation area. The method includes the steps that a PI controller is adopted to a rotating speed loop; a current controller based on resonance control is used for a dq shaft electric current loop, and parameter setting is carried out on the current controller; the PI controller is adopted in a field-weakening control link, and output of the PI controller serves as a d shaft current set value through an amplitude limiting link; according to set voltage vector dq shaft components output by the current controller, the duty ratio is calculated through an SVPWM overmodulation link, and a PWM signal driving motor is produced. The method suppresses current harmonics caused by flux weakening overmodulation, open-loop gains of the current loop are increased, and current, harmonic and torque fluctuation caused by overmodulation can be effectively suppressed.

The present invention comprises a method and apparatus for continuously, controlling a gain of an amplifier circuit while switching between open-loop and closed-loop power control. A control circuit controls the gain of the amplifier circuit during open-loop and closed-loop power control modes based on selected references. Before the switch from open-loop to closed-loop power control, the control circuit determines a closed-loop reference based on a power measured at the amplifier circuit output before the switch. After the switch, the control circuit controls the gain of the amplifier circuit based on the determined closed-loop reference. Before switching from closed-loop to open-loop power control, the control circuit generates a difference between a current open-loop reference and a previous open-loop reference. After the switch, the control circuit controls the gain of the amplifier circuit based on an open-loop gain control signal generated by applying the difference to a previous closed-loop gain control signal.

A low-dropout linear regulator includes an error amplifier which includes a cascaded arrangement of a differential amplifier and a gain stage. The gain stage includes a transistor driven by the differential amplifier to produce at a drive signal for an output stage of the regulator. The transistor is interposed over its source-drain line between a first resistive load included in a RC network creating a zero in the open loop gain of the regulator, and a second resistive load to produce a drive signal for the output stage of the regulator. The second resistive load is a non-linear compensation element to render current consumption linearly proportional to the load current to the regulator. The first resistive load is a non-linear element causing the frequency of said zero created by the RC network to decrease as the load current of the regulator decreases.

The invention discloses a method and a device for precisely measuring temperatures of platinum resistors. The scheme for measuring the temperatures of the micro-current-drive four-wired Pt100 platinum resistors includes that the device for precisely measuring the temperatures of the platinum resistors comprises a constant-current source drive circuit, a four-wired platinum resistor interface circuit, an instrument amplifier circuit, an anti-aliasing filter circuit, a sampling hold circuit, an A / D (analog / digital) sampling circuit and a single chip microcomputer system. A constant-current source comprises two low-noise and low-offset bipolar operational amplifiers OP07CD with high open-loop gain; the four-wired platinum resistor interface circuit is divided into a constant-current source power lead and a voltage drive lead; the instrument amplifier circuit comprises a double-stage differential amplifier circuit; the anti-aliasing filter circuit is an RC low-pass filter circuit; an A / D converter is a 24-bit high-resolution A / D converter CS5550. The method and the device have the advantage that the measurement precision is high, calibrated temperature measurement errors are smaller than + / -0.03 DEG C, and requirements of industrial production procedures on high temperature measurement precision can be met.

An improved Smith predicting controlling algorithm comprises the following steps: designing a fuzzy adaptive PID controller to replace an original PID controller, wherein the fuzzy adaptive PID controller mainly comprises a PID control regulator and a fuzzy inference engine, and modifying a PID control parameter according to a fuzzy control rule in real time by using an error e and the change rate ec of the error as the input of the controller and the kp, ki and kd of the PID control parameter as the output, so as to meet the requirements of e and ec for the self-regulation of the PID parameter at different moments; adding an inner feedback loop, sending a feedback signal to a predicting model and an input end of an actually-controller object by the inner feedback loop at the same time, comparing the feedback signal with the output of a main controller, using the difference as an input signal of the actually-controlled object and the predicting model and introducing an adaptive regulator. Therefore, the problem of deviation caused by the change of an open-loop gain parameter is solved by changing the value of a proportional controller continuously.

An open loop gain adjustment method and apparatus are provided for adjusting the gain of a TIA of an optical RX module based on measurements of the BER of the optical link in which the optical RX module is employed. The gain of the TIA is adjusted until a determination is made that a satisfactory or optimum link BER has been achieved.

An operational amplifier includes a transfer circuit, a cascode control circuit, and a slew rate boost circuit. The transfer circuit is configured to apply a transfer function to a received input signal and the application of the transfer function to the received input signal is effective to create an output signal. The cascode circuit is coupled to the transfer circuit. The cascode circuit is configured to increase an open loop gain of the operational amplifier. The slew rate boost circuit is coupled to the cascode circuit. The slew rate boost circuit is configured to increase the slew rate of the operational amplifier without necessarily increasing the power consumption of the operational amplifier.

The invention relates to the technical field of spacecraft control and particularly discloses an integrated analyzing and setting method for control parameters of a three-loop automatic pilot. The integrated analyzing and setting method comprises the following steps of: firstly, establishing a control loop model of the three-loop automatic pilot; secondly, setting a pitching motion relative damping coefficient after compensating an attitude angular velocity feedback circuit to acquire an attitude angular velocity control parameter and the open-loop cross-over frequency of the attitude angular velocity feedback circuit; thirdly, acquiring an open-loop gain system of a control system according to an open-loop transmission function of the control system and acquiring a closed-loop transmission function which is inputted to a guidance spacecraft by an overload instruction after correction and is outputted in an overload manner; and fourthly, acquiring the attitude angular velocity control parameter, an overload feedback control parameter and an overload instruction correction parameter. According to the integrated analyzing and setting method, the solving of a nonlinear equation is avoided; in addition, attitude stability and attitude control precision of the guidance spacecraft can be maintained by the acquired parameter under various single deviations and combined deviation and the balancing state of the spacecraft required by the guidance instruction is quickly realized.

A system provides closed-loop gain control in a WCDMA mode and open loop control in an EDGE / GSM mode. Gain control is distributed across analog devices and a digital sealer in a wireless receiver. In the WCDMA mode, a loop filter generates an error signal that is forwarded to analog and digital control paths. The analog control path includes a first adder, a programmable hysteresis element, and a lookup table. The analog control signal is responsive to thresholds, which when used in conjunction with a previous gain value determine a new gain value. The digital control path includes a second adder, a programmable delay element, and a converter. A control word is responsive to a difference of the error signal, a calibration value, and the analog control signal. Blocker detection is provided in the WCDMA mode of operation. A controller sets system parameters using a state machine.

The present invention refers, inter alia, to pixel circuits. The pixel circuit according to embodiments of the invention may include a photo-sensitive device having charge storage capability connected to a sense node. The pixel circuit may further include an inverting amplifier which is able to amplify a voltage from the sense node to a voltage on an output node of the amplifier, when being operated in open-loop configuration; and a reset switch being able to connect the input and output nodes of the inverting amplifier and thus to reset the inverting amplifier to an operating point providing high open loop gain by temporarily establishing negative feedback. Moreover, the pixel circuit may include a low-pass filter at the output node of the inverting amplifier for limiting the signal frequencies passing to the readout node to those frequencies that contain useful signal information. Additional and alternative embodiments are specified and claimed.

The invention relates to a pipelined-successive approximation register analog-to-digital converter applying an open-loop gain stage. A signal channel is formed by connecting a first-level successive approximation register analog-to-digital converter circuit, a voltage gain which is used for amplifying a surplus voltage output by the first-level successive approximation register analog-to-digital converter circuit, a tunable gain for carrying out gain calibration on the voltage gain, and a second-level successive approximation register analog-to-digital converter circuit in sequence. The pipelined-successive approximation register analog-to-digital converter also comprises a pseudo-random number generator and a background calibration engine circuit, which are used for calibrating various simulation mismatches of the signal channel. The voltage gain is the open-loop gain stage. According to the converter, a relatively high signal to noise ratio can be obtained, a signal conversion speed and resolution can be improved, the system power consumption can be reduced, and the system robustness can be improved.

The invention discloses a voltage regulation method applicable to a frequency conversion alternating-current generator, and belongs to the technical field of three-level type frequency conversion alternating-current generators. According to the voltage regulation method, a one-level DC-DC converter is additionally arranged between a permanent magnet pilot exciter and an alternating-current exciter, the input-output characteristic curve of the DC-DC converter is designed, and when the voltage of the no-load end of the generator is a reference voltage at any rotating speed of the generator, the duty ratio of an excitation main power tube is constant. Meanwhile, open-loop gain of a forward path of a voltage regulation system can not be affected by the rotating speed of the generator.

An electronic amplifier circuit comprising an operational amplifier circuit, such as a two-stage operational amplifier circuit, in tandem with a operational transconductance amplifier. The electronic amplifier circuit has high open-loop gain and high gain-bandwidth while maintaining stability over a wide range of operating parameters.

A technique for calibrating the open-loop transmit power of a wireless communication device overcomes the inherent nonlinearities in the gain control input of a variable gain amplifier (VGA). In one embodiment, a feedback circuit generates a signal indicative of the transmit power. This signal is compared with a desired transmit power level, which comprises an open-loop gain component and a closed-loop gain component. The desired transmit power level is compared with the actual transmit power level and an error signal is generated. The error signal is used to alter the gain of the VGA in the transmitter to thereby adjust the actual transmit power level to correspond with the desired transmit power level. In alternative embodiment, the receiver portion, which also contains a VGA, is pre-calibrated in a conventional manner. During a transmitter calibration process, the transmitter is coupled to the receiver input through a mixer and filter. The pre-calibrated receiver determines the actual transmit power level. The difference is used to generate error correction data to adjust for non linearities in the gain control input of the transmitter VGA.

A linear voltage regulator includes a Miller frequency compensation having a movable zero, which tracks the frequency of the load pole as the load condition changes. The compensated voltage regulator maintains stability under variable load conditions. Because of the Miller effect, DC open-loop gain and bandwidth are not sacrificed for stability. The compensated voltage regulator can therefore maintain high power supply rejection ratio (PSRR).

A method and apparatus of mitigating multipath coupling interference in a wireless repeater system 10 includes measuring an error signal E(z) in a signal path of the repeater which contains the desired communication signals and the multipath coupling interference and determining a cepstrum cee[n] of the error signal E(z), wherein the cepstrum cee[n] is reflective of the open-loop gain G(z) of the system. The method further includes extracting the impulse response of the open-loop gain G(z) from the cepstrum cee[n] of the error signal E(z), calculating a plurality of cancellation filter coefficients using the extracted impulse response, and adaptively applying the plurality of filter coefficients to an adjustable filter to generate the cancellation signal necessary to mitigate the multipath coupling interference.

The present invention provides a flyback power converter, a secondary side control circuit, and a control method thereof. The flyback power converter converts an input voltage to an output voltage, and provides a load current to a load circuit. The flyback power converter includes: a transformer circuit, a power switch circuit, a switch current sense circuit, a primary side control circuit, and a secondary side control circuit. The secondary side control circuit adaptively adjusts a frequency of a zero of a compensator gain function and / or a mid-frequency gain of the compensator gain function according to the load current, such that a number of poles of a system open loop gain function of the flyback power converter is at most more than a number of zeroes of the system open loop gain function by one under a crossover frequency.

The invention relates to a dynamic compensation method and a related device of a programmable gain amplifier. The programmable gain amplifier includes: an operational amplifier connected to a plurality of resistors, so that the operational amplifier can realize closed feedback control and has a closed-loop gain as the right formula; wherein, β is a feedback factor, which can be determined by the plurality of resistors The resistance value is determined, and A(s) is the open-loop gain of the operational amplifier, and the operational amplifier includes a first-stage amplifying circuit and a second-stage amplifying circuit, and a variable compensation capacitor is provided in the first-stage amplifying circuit Between the output end of the second-stage amplifying circuit and the output end of the second-stage amplifying circuit, the main pole of the open-loop gain of the operational amplifier can be changed as the capacitance value of the variable compensation capacitor changes. The invention can adjust the bandwidth of the operational amplifier by changing the equivalent capacitance value of the variable compensation capacitor.

The invention provides a low dropout (LDO) constant voltage control circuit, which belongs to the field of semiconductor integrated circuits. For the problem of poor overall performance of an LDO system which has large open loop gain, unstable loop and small open loop gain in the prior art, the LDO constant voltage control circuit comprises a reference voltage module, an error amplifier module, a driving tube P1, a divider resistor R1 and a divider resistor R2, wherein the error amplifier module comprises a first-stage amplifier, a second-class amplifier and a second-class amplifier and a compensation circuit which is connected with the second-class amplifier in parallel; and the first-class amplifier is connected with the parallel circuit of the compensation circuit and the second-class amplifier in series. The LDO constant voltage control circuit is applied to portable electronic equipment.

The present invention implements a servo system which can support changes of the higher resonance frequencies of the actuator with a simple configuration at low cost. The servo system comprises a head 3 which at least reads a disk 1, a carriage 5 which drives the head 3 to the track position of the disk 1, a detection circuit 9 which detects a positional error with respect to the track from the read output of the head, and the servo control unit 11 which controls the carriage such that the head follows up the track according to the positional error, wherein the servo control unit 11 further comprises a digital filter for increasing gain so that the open loop characteristic of the tracking servo system by the servo control unit has a gain higher than the open loop gain of the phase cross-over frequency f6 in a frequency area which is higher than the phase cross-over frequency f6 but lower than the higher resonance frequency f9 of the carriage and where the gain does not becomes OdB or more at a frequency where phase is (−180+360×N)°. Since gain is increased, phase margin is increased.

It should be possible to quickly and effectively adjust a hearing aid even in the high-frequency range above 8 kHz. For this purpose it is provided that an open-loop gain measurement is carried out in the upper frequency range and a maximum amplification or a frequency-dependent maximum amplification curve is fixed. This maximum amplification in the high-frequency range should not be exceeded. The hearing aid wearer can then optionally select one of a plurality of amplification curves located there below. In the low-frequency range a conventional amplification adjustment is carried out for example by a prescriptive audiogram-based formula. A hybrid adjustment procedure that is easy to carry out is thereby provided for the entire frequency range.

A device capable of receiving one or more digital stimulus signals and accurately measuring an open-loop gain of an amplifier comprises: a digital charge converter (DCC), a charge integrator, an A / D converter, a control logic circuit and an arithmetic logic unit (ALU). The DCC and the charge integrator are composed of a plurality of switches, one or more sampling capacitor, at least one integrating capacitor and an operational amplifier under test (OPAUT) with a single-ended output or differential-ended outputs. The DCC, the charge integrator, and the A / D converter are controlled by control signals generated by the logic control circuit and can be reconfigured as a first-order Sigma-Delta modulator capable of receiving at least one of the digital input stimulus signals. The ALU calculates the open-loop gain of the OPAUT with single-ended output or differential-ended outputs according to the digital stimulus signals and the digital output of the first-order Sigma-Delta modulator.