scholarly journals A Statistic-Based Calibration Method for TIADC System

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Kuojun Yang ◽  
Shulin Tian ◽  
Peng Ye ◽  
Peng Zhang ◽  
Yuanjin Zheng
Keyword(s):  
Sampling Rate ◽  
Calibration Method ◽  
Wide Frequency Range ◽  
Accurate Estimation ◽  
Analog To Digital ◽  
Average Value ◽  
Gain Error ◽  
Sampling Points ◽  
Interleaved Adc ◽  
Time Interleaved

Time-interleaved technique is widely used to increase the sampling rate of analog-to-digital converter (ADC). However, the channel mismatches degrade the performance of time-interleaved ADC (TIADC). Therefore, a statistic-based calibration method for TIADC is proposed in this paper. The average value of sampling points is utilized to calculate offset error, and the summation of sampling points is used to calculate gain error. After offset and gain error are obtained, they are calibrated by offset and gain adjustment elements in ADC. Timing skew is calibrated by an iterative method. The product of sampling points of two adjacent subchannels is used as a metric for calibration. The proposed method is employed to calibrate mismatches in a four-channel 5 GS/s TIADC system. Simulation results show that the proposed method can estimate mismatches accurately in a wide frequency range. It is also proved that an accurate estimation can be obtained even if the signal noise ratio (SNR) of input signal is 20 dB. Furthermore, the results obtained from a real four-channel 5 GS/s TIADC system demonstrate the effectiveness of the proposed method. We can see that the spectra spurs due to mismatches have been effectively eliminated after calibration.

An Encoder Used in an Ultra High-Speed Folding and Interpolating ADC

2014 ◽  
Vol 1049-1050 ◽  
pp. 687-690
Author(s):  
Yu Han Gao ◽  
Ru Zhang Li ◽  
Dong Bing Fu ◽  
Yong Lu Wang ◽  
Zheng Ping Zhang
Keyword(s):  
High Speed ◽  
Binary Code ◽  
Sampling Rate ◽  
Gray Code ◽  
Cmos Technology ◽  
Careful Consideration ◽  
Analog To Digital ◽  
Interleaved Adc ◽  
Time Interleaved ◽  
Error Suppression

High speed encoder is the key element of high speed analog-to-digital converter (ADC). Therefor the type of encoder, the type of code, bubble error suppression and bit synchronization must be taken into careful consideration especially for folding and interpolating ADC. To reduce the bubble error which may resulted from the circuit niose, comparator metastability and other interference, the output of quantizer is first encoded with gray code and then converted to binary code. This high speed encoder is verified in the whole time-interleaved ADC with 0.18 Bi-CMOS technology, the whole ADC can achieve a SNR of 45 dB at the sampling rate of 5GHz and input frequency of 495MHz, meanwhile a bit error rate (BER) of less than 10-16 is ensured by this design.

NEW SAMPLING METHOD TO IMPROVE THE SFDR OF WIDE BANDWIDTH ADC DEDICATED TO NEXT GENERATION WIRELESS TRANSCEIVER

2004 ◽  
Vol 13 (06) ◽  
pp. 1183-1201
Author(s):  
KAMAL EL-SANKARY ◽  
ALI ASSI ◽  
MOHAMAD SAWAN
Keyword(s):  
High Speed ◽  
Sampling Method ◽  
Dynamic Range ◽  
Sampling Rate ◽  
Analog To Digital ◽  
Wireless Transceiver ◽  
Spurious Free Dynamic Range ◽  
Interleaved Adc ◽  
Time Interleaved ◽  
Free Dynamic

Modern wireless communication standards that support high rates of voice and video streaming need high-speed Analog-to-Digital Converters (ADCs) with wide Spurious-Free Dynamic Range (SFDR). Conventional time-interleaved ADCs suffer from spurious components that seriously affect the SFDR. In this paper, we present the mathematical background describing the effect of randomizing the samples among the interleaved ADCs and we propose a digitally oriented method based on this analysis to randomize the mismatches among the ADC channels. Analyses and simulations show the effectiveness of the proposed approach in multi-channel ADCs with arbitrary bit resolution, channel's number and sampling rate. For a 10-bit 500 MS/s ADC, the SFDR achieved using the proposed randomizing method can be as wide as 75 dB, which is an enhancement of more than 26 dB comparing to the conventional time interleaved ADC.

scholarly journals Automatic Calibration Method of Channel Mismatches for Wideband TI-ADC System

Electronics ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 56 ◽  
Author(s):  
Jingyu Li ◽  
Jiameng Pan ◽  
Yue Zhang
Keyword(s):  
Dynamic Range ◽  
Dynamic Performance ◽  
Sampling Rate ◽  
Calibration Method ◽  
Perfect Reconstruction ◽  
Automatic Calibration ◽  
Sampling System ◽  
Analog To Digital ◽  
Large Bandwidth ◽  
Time Interleaved

Time-interleaved analog-to-digital converter (TI-ADC) technology can increase the sampling rate without changing resolution. But, the dynamic performance of TI-ADC system is seriously deteriorated by channel mismatches. Under the condition of large bandwidth, gain mismatch and timing mismatch vary with the frequency, which cannot be regarded as fixed values. To improve the dynamic performance of the TI-ADC system, an automatic calibration method of channel mismatches for wideband TI-ADC system is proposed in this article. Frequency-dependent channel mismatches are estimated by the algorithm based on sine fitting, and compensated by the means based on perfect reconstruction. The entire sampling and calculation process is automated and tedious operation is simplified. A 6.8-GS/s 12-bit wideband TI-ADC system is implemented. This sampling system can achieve SNDR (signal-to-noise and distortion ratio) above 49 dB and SFDR (spurious-free dynamic range) above 57 dB for an input signal from 100 MHz to 3300 MHz. The proposed calibration method improves the SNDR over 10 dB and the SFDR over 15 dB. The dynamic performance of the sampling system is close to that of its sub-ADC.

Timing Skew Calibration Method for TIADC-Based 20 GSPS Digital Storage Oscilloscope

2015 ◽  
Vol 25 (02) ◽  
pp. 1650007 ◽  
Author(s):  
Kuojun Yang ◽  
Jiali Shi ◽  
Shulin Tian ◽  
Wuhuang Huang ◽  
Peng Ye
Keyword(s):  
Input Signal ◽  
Sampling Rate ◽  
Calibration Method ◽  
Signal Frequency ◽  
Accurate Estimation ◽  
Storage Oscilloscope ◽  
Digital Storage ◽  
Digital Storage Oscilloscope ◽  
Time Interleaved ◽  
Timing Skew

Time-interleaved technique is widely used to increase the sampling rate of analog-to-digital converter (ADC). However, the channel mismatches degrade the performance of time-interleaved ADC (TIADC). When input signal frequency is very high, timing skews have significant effect on distortion. Therefore, a new timing skew calibration method is proposed in this paper. This method is based on the truth that timing skews are related to the product of the outputs of sub-ADCs. After timing skews are estimated, the digital controlled delay elements (DCDE) in ADC and phase locked loop (PLL) are utilized to calibrate timing skews. No auxiliary circuit and digital filter are needed for this calibration method. Simulation results show that the proposed method can estimate timing skew accurately. It is also proved that an accurate estimation can be obtained even the signal to noise ratio (SNR) of input signal is 20[Formula: see text]dB. The proposed method is employed to calibrate timing skews in a 16-channel TIADC-based 20[Formula: see text]GSPS digital storage oscilloscope (DSO). The experiment results demonstrate the usefulness of the proposed method. We can see that after timing skews are calibrated, the spectrum spurs have been effectively eliminated.

scholarly journals A 3GSps 12-bit Four-Channel Time-Interleaved Pipelined ADC in 40 nm CMOS Process

Electronics ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 1551 ◽  
Author(s):  
Jianwen Li ◽  
Xuan Guo ◽  
Jian Luan ◽  
Danyu Wu ◽  
Lei Zhou ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Cmos Process ◽  
Pipelined Adc ◽  
Least Significant Bit ◽  
Analog To Digital ◽  
Capacitor Mismatch ◽  
Gain Error ◽  
Spurious Free Dynamic Range ◽  
Time Interleaved ◽  
Free Dynamic

This paper presents a four-channel time-interleaved 3GSps 12-bit pipelined analog-to-digital converter (ADC). The combination of master clock sampling and delay-adjusting is adopted to remove the time skew due to channel mismatches. An early comparison scheme is used to minimize the non-overlapping time, where a custom-designed latch is developed to replace the typical non-overlapping clock generator. By using the dither capacitor to generate an equivalent direct current input, a zero-input-based calibration is developed to correct the capacitor mismatch and inter-stage gain error. Fabricated in a 40 nm CMOS process, the ADC achieves a signal-to-noise-and-distortion ratio (SNDR) of 57.8 dB and a spurious free dynamic range (SFDR) of 72 dB with a 23 MHz input tone. It can achieve an SNDR above 52.3 dB and an SFDR above 61.5 dB across the entire first Nyquist zone. The differential and integral nonlinearities are −0.93/+0.73 least significant bit (LSB) and −2.8/+4.3 LSB, respectively. The ADC consumes 450 mW powered at 1.8V, occupies an active area of 3 mm × 1.3 mm. The calculated Walden figure of merit reaches 0.44 pJ/step.

scholarly journals Mismatch error correction for time interleaved analog-to-digital converter over a wide frequency range

2018 ◽  
Vol 89 (8) ◽  
pp. 084709
Author(s):  
Zouyi Jiang ◽  
Lei Zhao ◽  
Xingshun Gao ◽  
Ruoshi Dong ◽  
Jinxin Liu ◽  
...  
Keyword(s):  
Error Correction ◽  
Wide Frequency Range ◽  
Analog To Digital Converter ◽  
Digital Converter ◽  
Frequency Range ◽  
Mismatch Error ◽  
Analog To Digital ◽  
Time Interleaved

A Time-Interleaved Statistically-Driven Two-Step Flash ADC for High-Speed Wireline Applications

2017 ◽  
Vol 26 (07) ◽  
pp. 1750118 ◽  
Author(s):  
Dengbao Liu ◽  
Lin He ◽  
Fujiang Lin ◽  
Ting Li ◽  
Yu-Kai Chou
Keyword(s):  
Probability Distribution ◽  
Input Signal ◽  
High Speed ◽  
Small Probability ◽  
Flash Adc ◽  
Analog To Digital ◽  
Second Stage ◽  
Large Probability ◽  
Interleaved Adc ◽  
Time Interleaved

This paper presents a statistically-driven two-step flash sub-analog-to-digital converter (ADC) to construct the high-speed time-interleaved ADC in wireline communication applications. The comparators in the flash sub-ADC are divided into the large probability first stage and the small probability second stage to take advantage of the nonuniform probability distribution of the input signal. At the first step of operation, the large probability first stage is activated while the small probability second stage is suspended. If the input signal is beyond the input range of the first stage, the segment selection signal will trigger proper segment in the second stage. Feed-forward equalization is proposed to manipulate the probability distribution of the ADC input signal. A possible implementation of the proposed ADC as well as the modulation and equalization scheme is presented to comply with the IEEE 802.3ap 10[Formula: see text]G Ethernet standard. In the case of a PAM-4 pseudorandom signal, the proposed solution achieves [Formula: see text] reduction on the average number of activated comparators compared to a conventional flash ADC.

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