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

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 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.