33results about How to "Reduce gain error" patented technology

A method and system in accordance with the present invention greatly reduces the gain error due to Raman gain tilt for individual channels in an optical communication system during a transient event by determining a shift in average power (and thus wavelength) and using the determined shift to alter the average gain in the optical communication system. In various embodiments of the present invention, the average gain of the optical communication system is altered by altering the average gain of an amplifier in the optical communication system. In alternate embodiments of the present invention having an in-line optical filter, the average gain of the optical communication system may be altered by altering the filtering of the optical channels in the optical communication system.

An optical amplification unit comprises at least one optical amplifier for amplifying an optical signal and a filter preceding or following the optical amplifier. The optical amplifier comprises a first measuring device for measuring a property of an input signal of the optical amplifier, a second measuring device for measuring a property of an output signal of the optical amplifier , and a control circuit for controlling a gain characteristic of the optical amplifier in dependence of said input and output signal properties. The filter exhibits a wavelength-dependent attenuation of the optical signal. The optical amplification unit is connectable to an optical fiber span and the filter is adapted to compensate for a span loss tilt caused by said optical fiber span An optical transmission system with at least one such optical amplification unit and corresponding methods.

The embodiment of the invention provides a digital control oscillator, a method for generating a quadrature carrier wave and a quadrature amplitude modulation system. The digital control oscillator comprises a DDS (Direct Digital Synthesizer) address accumulator, a phase register, a phase adder, a combining switch, a wavetable memory and a shunt switch. According to the embodiment of the invention, the generated quadrature carrier wave has strict phase orthogonality and amplitude consistency and small gain error; the carrier wave has high frequency resolution and short switching time and continuous phases; in addition, the digital control oscillator has the advantages of simple structure and low cost.

The present invention provides a pipelined successive approximation analog-to-digital converter and conversion method, including: a first-stage successive approximation analog-to-digital conversion module, a second-stage successive approximation analog-to-digital conversion module and a digital code error correction logic module; wherein, the first The stage successive approximation analog-to-digital conversion module includes a first capacitor array unit, an amplification unit, a latch comparison unit, a first register logic control unit and a control switch, and the amplification unit is multiplexed as a residual amplifier and a first-stage successive approximation analog-to-digital converter pre-amplifier for the comparator. The present invention completely eliminates the input offset voltage mismatch existing between the two by multiplexing the residual amplifier pre-amplifier, stabilizes the input swing of the residual amplifier, improves the linearity of the residual amplifier, and saves chip area ; and the gain error is obtained by multiplexing the second-stage successive approximation analog-to-digital conversion module, which reduces the gain error of the residual amplifier and improves the conversion accuracy of the entire pipelined successive approximation analog-to-digital converter.

The invention provides a linear photoelectric isolation circuit for suppressing temperature drift. The linear photoelectric isolation circuit comprises the components of a signal input source which isused for supplying an input signal; a signal conditioning unit which is connected with the signal input source and is used for converting the input signal to two signals with same amplitude, same waveform and opposite polarities; two optical coupler units which are connected with the signal conditioning unit and are used for transmitting the two signals; a differential operating unit which is connected with the optical coupler units and is used for performing operational processing on the signals that are output from the optical coupler units; and an output circuit which is connected with thedifferential operational unit and is used for outputting the signals after operational processing by the differential operating unit. The linear photoelectric isolation circuit has advantages of settling a signal gain error problem caused by the temperature drift and a waveform interference noise problem in signal isolated transmission, thereby accurate isolated transmission of the signal, and better satisfying an actual application requirement of the linear photoelectric isolation circuit in a high-voltage industrial field.

The invention provides an AC voltage commutating differential measuring device based on quantum voltage. The AC voltage commutating differential measuring device comprises a photoelectric commutated switch, two followers, two paths of voltage raising circuits, a differential driving circuit, a filtering circuit, an A / D sampling circuit, an FPGA time sequence control circuit, and an upper computerand data processing module that are connected successively. The upper computer and data processing module stores differential signals measured twice before and after commutation of the photoelectric commutated switch; a measured AC voltage is reconstructed by using the differential signal and an AC quantum voltage; and amplitudes of the AC voltage signals in two reconstruction are obtained based on FFT operation, wherein the average value of the amplitudes is the voltage amplitude of the AC voltage. Therefore, the error of the measurement system is greatly attenuated and the accuracy of the ACvoltage amplitude measurement is improved.

The invention provides a harmonic voltage measurement method based on alternating quantum voltage, which belongs to the field of measurement. The method first generates a periodic signal containing harmonics, and then determines the sampling frequency and the number of steps. Among them, the sampling frequency should be determined according to the fundamental frequency, with the goal of realizing the whole cycle sampling. The number of steps should be determined according to the number of sampling points per cycle. Next, a ladder AC quantum voltage signal is generated, and the ladder AC quantum voltage signal should be generated according to the signal to be measured. Then sample the differential signals before and after commutation, and process them separately, that is, perform data screening and recovery, perform weighted Fourier transform on the signal data, and calculate the amplitude of the fundamental wave and harmonic contained in the measured signal and phase, and finally calculate the mean value of the results obtained before and after commutation.

The invention provides a capacitance-voltage conversion circuit for a MEMS capacitive sensor, comprising: a voltage excitation source, a common-mode charge controller, and a charge-voltage conversion module; wherein, the charge-to-voltage conversion module includes: a first-stage differential amplifier, a first-stage differential amplifier, a Two-stage differential amplifier, gain error corrector, active noise canceller and charge feedback unit, because after the first-stage differential amplifier amplifies the set-up noise signal of the parasitic capacitance of the preset capacitance sensor, there are some parts connected to the first-stage differential amplifier. The source noise canceller can absorb the set-up noise signal, and the gain error corrector connected to the active noise canceller and the second-stage differential amplifier respectively can correct the gain errors generated by the first-stage differential amplifier and the second-stage differential amplifier. Corrected, thereby improving gain accuracy while reducing noise, resulting in a significant increase in energy efficiency.

The invention discloses a method for eliminating multi-channel gain errors of an EEG signal acquisition system, which comprises acquisition electrodes sequentially arranged in the channel signal flow direction, a decoupling input capacitor, an input unit, intra-channel chopping modulation, and inter-channel chopping Modulation, fully differential closed-loop amplifier unit, inter-channel chopping demodulation, intra-channel chopping demodulation, low-pass filter and output unit, said method includes intra-channel chopping modulation-multistage inter-channel chopping modulation-amplification- Process of multi-stage inter-channel chopping demodulation-intra-channel chopping demodulation-low-pass filtering. The invention eliminates the gain error between channels, ensures the accuracy of signal acquisition, and avoids the flicker noise in the amplifier.

The invention relates to a multiplication-type A / D (Analog / Digital) converter capable of correcting a limited gain error, which comprises an amplifying circuit unit and a limited gain error correcting circuit unit. According to the invention, two compensation capacitors and an amplifier constitute the limited gain error correcting circuit unit, part of output quantity is adjustably compensated into the input end of an operation amplifier, nonzero / virtual earth / is adjusted, and the limited gain error is greatly reduced; after the adoption of the limited gain error correcting circuit unit, the limited gain error of the whole streamlined A / D converter is reduced by one order of magnitude; and in the invention, gain of the amplifier is adjustable, and therefore the limited gain error causedby temperature and process changes is effectively offset. According to the invention, the limited gain error correcting circuit has the characteristics of small limited gain error, low power consumption and high reliability and is suitable for the fields of high-speed, high-precision, low power-consumption streamlined A / D converters.