SEMICONDUCTOR INTEGRATED CIRCUITS

An S/H circuit with parasitics optimized for IF-sampling

Xuqiang Zheng1, 2, Fule Li1, , Zhijun Wang1, Weitao Li1, Wen Jia3, Zhihua Wang1 and Shigang Yue2

+ Author Affiliations

 Corresponding author: Fule Li, Email: lifule@tsinghua.edu.cn

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Abstract: An IF-sampling S/H is presented, which adopts a flip-around structure, bottom-plate sampling technique and improved input bootstrapped switches. To achieve high sampling linearity over a wide input frequency range, the floating well technique is utilized to optimize the input switches. Besides, techniques of transistor load linearization and layout improvement are proposed to further reduce and linearize the parasitic capacitance. The S/H circuit has been fabricated in 0.18-μm CMOS process as the front-end of a 14 bit, 250 MS/s pipeline ADC. For 30 MHz input, the measured SFDR/SNDR of the ADC is 94.7 dB/68. 5dB, which can remain over 84.3 dB/65.4 dB for input frequency up to 400 MHz. The ADC presents excellent dynamic performance at high input frequency, which is mainly attributed to the parasitics optimized S/H circuit.

Key words: sample-and-hold (S/H)IF-samplingbootstrapped switchesparasitics optimizationhigh linearity



[1]
Chu M, Kim B, Lee B G. A 10-bit 200-MS/s zero-crossing-based pipeline ADC in 0.13-μm CMOS technology. IEEE Trans Very Large Scale Integration Systems, 2015, 23(11):2671
[2]
Sehgal R, van der Goes F, Bult K. A 12 b 53 mW 195 MS/s pipeline ADC with 82 dB SFDR using split-ADC calibration. IEEE J Solid-State Circuits, 2015, 50(7):1592
[3]
Yin Xiumei, Wei Qi, Xu Lai, et al. A low power 12-b 40-MS/s pipeline ADC. Journal of Semiconductors, 2012, 31(3):035006
[4]
Chen Zhenhai, Qian Hongwen, Huang Songren, et al. A low power time-interleaved 10-bit 250-MSPS charge domain pipelined ADC for IF sampling. Journal of Semiconductors, 2013, 34(6):065005
[5]
Dessouky M, Kaiser A. Input switch configuration for rail-to-rail operation of switched opamp circuits. Electron Lett, 1999, 35(1):8
[6]
Zhao Nan, Luo Hua, Wei Qi, et al. A 14-bit 100-MS/s 85.2-dB SFDR pipelined ADC without calibration. Journal of Semiconductors, 2014, 35(7):075006
[7]
Luo L Lin K, Cheng L, et al. A digitally calibrated 14-bit linear 100-MS/s pipelined ADC with wideband sampling front end. IEEE European Solid-State Circuits Conference, 2009:472
[8]
Cheng C, Chang S J, Huang G Y, et al. A 10-bit 50-MS/s SAR ADC with a monotonic capacitor switching procedure. IEEE J Solid-State Circuits, 2010, 45(4):731
[9]
Jing Xin, Zhuang Yiqi, Tang Hualian, et al. A power-efficient 12-bit analog-to-digital converter with a novel constant-resistance CMOS input sampling switch. Journal of Semiconductors, 2014, 35(2):025002
[10]
Ali A, Morgan A, Dillon C, et al. A 16-bit 250-MS/s IF sampling pipelined ADC with background calibration. IEEE J Solid-State Circuits, 2010, 45(12):2602
[11]
Wang Z, Wang M, Gu W, et al. A high-linearity pipelined ADC with opamp split-sharing in a combined front-end of S/H and MDAC1. IEEE Trans Circuits Syst I:Regular Papers, 2013, 60(11):2834
[12]
Yang C, Li L, Li W, et al. An 85 mW 14-bit 150 MS/s pipelined ADC with 71.3 dB peak SNDR in 130 nm CMOS. IEEE Asian Solid-State Circuits Conference, 2013:85
Fig. 1.  Flip-around S/H circuit with bottom-plate sampling (single-ended for simplification).

Fig. 2.  Conventional bootstrapped switch.

Fig. 3.  Bulk switching with (a) non-floating well and (b) floating well.

Fig. 4.  Nonlinear load due to M4.

Fig. 5.  A technique to linearize the load effect of M4.

Fig. 6.  Simulated SFDR versus input frequency.

Fig. 7.  Layout method for feed-forward coupling cancellation.

Fig. 8.  Layout method to reduce parasitic capacitance.

Fig. 9.  Improved bootstrapped input switch.

Fig. 10.  (Color online) The chip micrograph.

Fig. 11.  16 K samples FFT spectrum at fin D 30 MHz and 403 MHz.

Fig. 12.  Measured SFDR and SNDR versus input frequency at 250 MS/s.

Table 1.   Comparison of measured performance.

ReferenceProcessResolution Sampling rate(MS/s)SFDR(dBc)SNDR(dB)
[7]CMOS 0.18-μm 14 10084.1 @ 69 MHz
74.6 @ 403 MHz
65.7 @ 69 MHz
63.1 @ 403 MHz
[10]*BICMOS 0.18-μm 16 25090.0 @ 10 MHz
NA @ IF
77.8 @ 10 MHz
BICMOS 0.18-μm1612595.0 @ 10 MHz
80.0 @ 300 MHz
NA
[11]CMOS 0.18-μm1410089.1 @ 15.5 MHz
87.3 @ 48.8 MHz
82.7 @ 220 MHz
70.2 @ 15.5 MHz
69.2 @ 48.4 MHz
66.2 @ 220 MHz
[12]CMOS 0.13-μm1415091.0 @ 30 MHz
78.4 @ 149 MHz
71.5 @ 250 MHz
71.0 @ 30 MHz
68.1 @ 149 MHz
65.0 @ 250 MHz
This workCMOS 0.18-μm 1425094.7 @ 30 MHz
89.5 @ 200 MHz
84.3 @ 403 MHz
68.5 @ 30 MHz
67.5 @ 200 MHz
65.8 @ 403 MHz
*Compared with the design without input buffer
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[1]
Chu M, Kim B, Lee B G. A 10-bit 200-MS/s zero-crossing-based pipeline ADC in 0.13-μm CMOS technology. IEEE Trans Very Large Scale Integration Systems, 2015, 23(11):2671
[2]
Sehgal R, van der Goes F, Bult K. A 12 b 53 mW 195 MS/s pipeline ADC with 82 dB SFDR using split-ADC calibration. IEEE J Solid-State Circuits, 2015, 50(7):1592
[3]
Yin Xiumei, Wei Qi, Xu Lai, et al. A low power 12-b 40-MS/s pipeline ADC. Journal of Semiconductors, 2012, 31(3):035006
[4]
Chen Zhenhai, Qian Hongwen, Huang Songren, et al. A low power time-interleaved 10-bit 250-MSPS charge domain pipelined ADC for IF sampling. Journal of Semiconductors, 2013, 34(6):065005
[5]
Dessouky M, Kaiser A. Input switch configuration for rail-to-rail operation of switched opamp circuits. Electron Lett, 1999, 35(1):8
[6]
Zhao Nan, Luo Hua, Wei Qi, et al. A 14-bit 100-MS/s 85.2-dB SFDR pipelined ADC without calibration. Journal of Semiconductors, 2014, 35(7):075006
[7]
Luo L Lin K, Cheng L, et al. A digitally calibrated 14-bit linear 100-MS/s pipelined ADC with wideband sampling front end. IEEE European Solid-State Circuits Conference, 2009:472
[8]
Cheng C, Chang S J, Huang G Y, et al. A 10-bit 50-MS/s SAR ADC with a monotonic capacitor switching procedure. IEEE J Solid-State Circuits, 2010, 45(4):731
[9]
Jing Xin, Zhuang Yiqi, Tang Hualian, et al. A power-efficient 12-bit analog-to-digital converter with a novel constant-resistance CMOS input sampling switch. Journal of Semiconductors, 2014, 35(2):025002
[10]
Ali A, Morgan A, Dillon C, et al. A 16-bit 250-MS/s IF sampling pipelined ADC with background calibration. IEEE J Solid-State Circuits, 2010, 45(12):2602
[11]
Wang Z, Wang M, Gu W, et al. A high-linearity pipelined ADC with opamp split-sharing in a combined front-end of S/H and MDAC1. IEEE Trans Circuits Syst I:Regular Papers, 2013, 60(11):2834
[12]
Yang C, Li L, Li W, et al. An 85 mW 14-bit 150 MS/s pipelined ADC with 71.3 dB peak SNDR in 130 nm CMOS. IEEE Asian Solid-State Circuits Conference, 2013:85
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    Received: 27 September 2015 Revised: 09 December 2015 Online: Published: 01 June 2016

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      Xuqiang Zheng, Fule Li, Zhijun Wang, Weitao Li, Wen Jia, Zhihua Wang, Shigang Yue. An S/H circuit with parasitics optimized for IF-sampling[J]. Journal of Semiconductors, 2016, 37(6): 065005. doi: 10.1088/1674-4926/37/6/065005 X Q Zheng, F L Li, Z J Wang, W T Li, W Jia, Z H Wang, S G Yue. An S/H circuit with parasitics optimized for IF-sampling[J]. J. Semicond., 2016, 37(6): 065005. doi: 10.1088/1674-4926/37/6/065005.Export: BibTex EndNote
      Citation:
      Xuqiang Zheng, Fule Li, Zhijun Wang, Weitao Li, Wen Jia, Zhihua Wang, Shigang Yue. An S/H circuit with parasitics optimized for IF-sampling[J]. Journal of Semiconductors, 2016, 37(6): 065005. doi: 10.1088/1674-4926/37/6/065005

      X Q Zheng, F L Li, Z J Wang, W T Li, W Jia, Z H Wang, S G Yue. An S/H circuit with parasitics optimized for IF-sampling[J]. J. Semicond., 2016, 37(6): 065005. doi: 10.1088/1674-4926/37/6/065005.
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      An S/H circuit with parasitics optimized for IF-sampling

      doi: 10.1088/1674-4926/37/6/065005
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      Poject supported by the Shenzhen Project (No. JSGG20150512162029307).

      Poject supported by the Shenzhen Project No. JSGG20150512162029307

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      • Corresponding author: Email: lifule@tsinghua.edu.cn
      • Received Date: 2015-09-27
      • Revised Date: 2015-12-09
      • Published Date: 2016-06-01

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