Forward stage and backward stage switching method for pipelined successive approximation analog-to-digital converter

Abstract

The invention discloses a forward stage and backward stage switching method for a pipelined successive approximation analog-to-digital converter, and relates to the fields of microelectronics and solid-state electronics, in particular to the pipelined successive approximation analog-to-digital converter. An additional operational amplifier does not need to be introduced to perform noise shaping, any correction algorithm does not need to be introduced, and Dither does not need to be introduced. Accumulation of errors of capacitor mismatch on the same code word can be avoided only by exchange of a first successive approximation analog-to-digital converter and a second successive approximation analog-to-digital converter between two conversions. Compared with a conventional correction method for increasing DNL / INL (Differential Nonlinearity / Integral Nonlinearity) based on the noise shaping, the correction algorithm or the Dither, the forward stage and backward stage switching method has the effects of simpler structure, smaller chip occupation area and higher easiness in on-chip implementation.

Description

technical field [0001] The invention relates to the fields of microelectronics and solid electronics, in particular to a pipelined successive approximation analog-to-digital converter. Background technique [0002] In recent years, with the continuous development of technologies such as portable medical instruments, communications industry, security inspection systems, high-performance computing, biomedicine, and digital signal processing, the requirements for analog-to-digital converters are also increasing, driving the development of analog-to-digital converters. To the direction of high speed, high precision and low power consumption. The field of mobile communication generally requires the resolution of the analog-to-digital converter to be above 10 bits and the speed to be greater than 100MHZ. The United States imposes export controls on my country in the field of high-speed and high-precision analog-to-digital converters. Therefore, research on high-performance analog...

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Problems solved by technology

The ADC with noise shaping function comprehensively utilizes the advantages of Nyquist ADC and oversampling ADC, but it needs to use high-performance operational amplifier to construct the transfer function to realize the function of noise shaping, which greatly increases the power consumption; literature [Y.S.Shu , B.S.Song, "A15-bitlinear20-MS / spipelinedADC digitally calibrated with signal-dependent dithering", IEEE Journal of Solid-State Circuits, pp.342--350, 2008, 43(2).] The proposed Dither technology can enhance the signal-to-noise of traditional Nyquist ADC Ratio, improve the linearity of the ADC, but Dither technology requires an ultra-high-precision DAC to convert Dither into an analog signal, introduce it into the ADC input and superimpose the input signal. Therefore, in order to avoid overflow, the amplitude range of the input signal will be reduced, and Dither technology requires the design of ultra-high-precision DAC, which becomes another bottleneck, which limits the application of Dither technology; literature [W.Liu, P.Huang, Y.Chiu, "A12-bit, 45-MS / s, 3- mWRedundantSuccessiveApproximationRegisteranalog-to-DigitalConverterWithDigitalCalibration”, IEEE Journal of Solid-State Circuits, pp.2661--2672, 2011, 46(11).] The proposed background LMS correction algorithm converts the same input voltage twice, and the LMS algorithm converts the result twice according to the ADC Different, the capacitor mismatch error is calculated and corrected. Although this algorithm does not require an accurate reference source, converting the same input voltage twice results in a half of the sampling rate, which seriously sacrifices speed.

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