A 10-bit 100-Msps low power time-interleaved ADC using OTA sharing

A high performance 10-bit 100-MS/s two-channel time-interleaved pipelined ADC is designed for intermediate frequency 3G receivers,and OTA is shared among the channels for low power dissipation.Offset mismatch, gain mismatch and time skew mismatch are overcome by OTA sharing,increasing the accuracy of each channel and global passive sampling respectively.The linearity deterioration caused by the charge injection of the output switch and the crosstalk of the off-switch capacitor is removed by modifying the...     

10bit 100M低功耗时间交织运放共享模数转换器设计

本文设计了一个应用于3G接收机中频的10比特100兆采样率的双通道时间交织流水线模数转换器,为了降低功耗,运放在两通道间共享。针对通道间的直流失调失配,增益失配以及采样时间偏差,设计分别采用共享运放,增加每个通道转换精度以及全局采样技术来加以解决。通过改变时序,消除了输出开关电荷注入以及断开开关的电容造成的串扰,从而提高了整个模数转换器的线性度。整个模数转换器的供电电压为3.3V,功耗为70毫瓦,采用了180纳米CMOS工艺,面积为3×2mm2,在奈奎斯特频率以内,其杂散无失真动态范围大于70dB,其信杂比大于56dB。     

A 14b 100-MS/s Time-Interleaved A/D Converter

This article presents a 14-bit, 100-MS/s time-interleaved pipeline ADC, which samples input signal from 210-MHz IF-band. Digital self-calibration is employed to compensate gain mismatch and offset between time-interleaved channels as well as mismatches arise from a single ADC channel. A timing skew-insensitive parallel S/H circuit is utilized in order to avoid timing skew between parallel ADC channels. The ADC, fabricated in a 0.35-μm BiCMOS (SiGe) takes an area of 10.2 mm², reaches an ENOB of 11.4 bits with a 79.9-dB SFDR at 192.5-MHz input and draws 1.4 W from a 3.0-V supply.     

A 25-GS/s 6-bit time-interleaved SAR ADC with design-for-test memory in 40-nm low-leakage CMOS

This paper presents a 25-GS/s 6-bit time-interleaved (TI) SAR ADC in a 40-nm CMOS low-leakage (LL) process. The prototype utilizes 4 × 12 hierarchical sampling architecture to reduce the complexity of track-and-hold circuits and the timing skew calibration. The single-channel SAR ADC adopts asynchronous processing with two alternate comparators. A partially active reference voltage buffer is designed to reduce the power consumption. The method based on sinusoidal signal approximation is employed to calibrate timing skew errors. To characterize the ultra-high-speed ADC, an on-chip design-for-test memory is designed. At 25 GS/s, the ADC achieves the SNDR of 32.18 dB for low input frequency and 27.28 dB for Nyquist frequency. The chip consumes 800 mW and occupies 1.3 × 2.6 mm², including the TI ADC core and memory.     

Dual Time-Interleaved Successive Approximation Register ADCs for an Ultra-Wideband Receiver

Ultra-wideband radio requires Nyquist sampling rates of at least 500 MS/s with low resolutions. While flash is the traditional choice for these specifications, a comparative energy model is used to show the potential energy savings of the time-interleaved successive approximation register architecture, which requires only a linear number of comparisons versus exponential for flash. A dual 500-MS/s, 5-bit ADC chip is implemented in a 0.18-mum CMOS process, with both ADCs synchronized for use in an I/Q UWB receiver. Each ADC uses a 6-way time-interleaved SAR topology with full custom logic, self-timed bit-cycling, and duty cycling of the comparator preamplifiers to enable 500-MS/s operation with 7.8 mW power consumption. The output resolution is adjustable down to the 1-bit level for additional power savings     

A 40 Gs/s Time Interleaved ADC Using SiGe BiCMOS Technology

The search for high speed, high bandwidth A/D converters is ongoing, and techniques to push the envelope are constantly being developed. In this paper an open loop, scalable, time-interleaved ADC architecture is presented, as well as a 60 GHz Colpitts oscillator. With the use of double-sampling, the timing skew requirements between channels is greatly relaxed, allowing sampling rates of up to 40 Gs/s at 4-bits of accuracy. This circuit is implemented using the IBM 8HP SiGe technology, with fT of 210 GHz. The performance of the 8HP ADC is validated by measurement. In addition, simulations with an experimental 8XP transistor model provided by IBM with a 350 GHz fT suggest that 30% more circuit speed is possible by just swapping the transistors.      

采用环型运放的12-bit 40-MS/s采样保持电路设计实现

为了保证模数转换器转换速度和精度,本文基于0.18微米工艺,设计实现了一款应用于12-bit 40-MS/s流水线ADC前端的采样保持电路.所采用的环型结构运放,可以简化设计、且占用面积小;同时,采用绝缘体上硅工艺,可以消除栅压自举开关中开关管的衬偏效应,改善开关的线性度,提高采样保持电路的性能.采样保持电路面积是0.023平方毫米.测试结果表明：在1.5V供电电压下,采样保持电路功耗是3.5mW;在1MHz输入频率、40MHz采样频率下,该采样保持电路无杂散动态范围可以达到76.85dB,满足12-bit 40-MS/s流水线模数转换器应用需求.     

500-MS/s 5-bit ADC in 65-nm CMOS With Split Capacitor Array DAC

A 500-MS/s 5-bit ADC for UWB applications has been fabricated in a 65-nm CMOS technology using no analog-specific processing options. The time-interleaved successive approximation register (SAR) architecture has been chosen due to its simplicity versus flash and its amenability to scaled technologies versus pipelined, which relies on operational amplifiers. Six time-interleaved channels are used, sharing a single clock operating at the composite sampling rate. Each channel has a split capacitor array that reduces switching energy, increases speed, and has similar INL and decreased DNL, as compared to a conventional binary-weighted array. A variable delay line adjusts the instant of latch strobing to reduce preamplifier currents. The ADC achieves Nyquist performance, with an SNDR of 27.8 and 26.1 dB for 3.3and 239 MHz inputs, respectively. The total active area is 0.9mm², and the ADC consumes 6 mW from a 1.2-V supply     

一种应用于流水线ADC采样保持电路的设计

介绍了一种应用于12位、10MS/s流水线模数转换器前端的高性能采样保持（SH）电路的设计。该电路采用全差分电容翻转型结构及下极板采样技术,有效地减少噪声、功耗及电荷注入误差。采用一种改进的栅源电压恒定的自举开关,极大地减小电路的非线性失真。运算放大器为增益增强型折叠式共源共栅结构,能得到较高的带宽和直流增益。该采样保...     

A silicon bipolar 4-bit 1-Gsample/s full Nyquist A/D converter

A four-bit silicon bipolar analog-to-digital converter (ADC) which is operational at the full Nyquist input frequency up to 1 Gsample/s (Gs/s) is discussed. The effective bit number at 1 Gs/s reduces to 3.5 bits on Nyquist conditions. The 3-dB large-signal analog bandwidth is 800 MHz and the maximum sampling rate reaches 2 Gs/s and beyond. The converter is built up by stacking of two three-bit subcircuits. The ADC architecture relies on a balanced structure mixing conventional flash-converter elements with analog encoding. Total power consumption is 2.4 W. Standard silicon bipolar technology is used without self-alignment     

A 1.8-V 22-mW 10-bit 30-MS/s Pipelined CMOS ADC for Low-Power Subsampling Applications

This paper describes a 10-bit 30-MS/s subsampling pipelined analog-to-digital converter (ADC) that is implemented in a 0.18 mum CMOS process. The ADC adopts a power efficient amplifier sharing architecture in which additional switches are introduced to reduce the crosstalk between the two opamp-sharing successive stages. A new configuration is used in the first stage of the ADC to avoid using a dedicated sample-and-hold amplifier (SHA) circuit at the input and to avoid the matching requirement between the first multiplying digital-to-analog converter (MDAC) and flash input signal paths. A symmetrical gate-bootstrapping switch is used as the bottom-sampling switch in the first stage to enhance the sampling linearity. The measured differential and integral nonlinearities of the prototype are less than 0.57 least significant bit (LSB) and 0.8 LSB, respectively, at full sampling rate. The ADC exhibits higher than 9.1 effective number of bits (ENOB) for input frequencies up to 30 MHz, which is the twofold Nyquist rate (fs/2), at 30 MS/s. The ADC consumes 21.6 mW from a 1.8-V power supply and occupies 0.7 mm², which also includes the bandgap and buffer amplifiers. The figure-of-merit (FOM) of this ADC is 0.26 pJ/step.     

A Time-Interleaved $DeltaSigma$-DAC Architecture Clocked at the Nyquist Rate

This paper describes a delta–sigma ( $DeltaSigma$) digital-to- analog converter (DAC) architecture that combines a polyphase decomposition of the interpolation filter and a time-interleaved error-feedback $DeltaSigma$ modulator. Noise-shaped oversampling is achieved while clocking the digital circuitry at the Nyquist rate. The design of a third-order 4-bit modulator with eight times oversampling using the architecture is presented. Results from a prototype current-DAC driven by a VHDL simulation of the digital design at 2.66 GHz show that 56-dB linearity is achievable in 90-nm CMOS within a 1-V supply over a 155-MHz signal bandwidth making the architecture suitable for emerging ultra-wide-band and 60-GHz radio applications.      

An 8-bit 200-MSample/s Pipelined ADC With Mixed-Mode Front-End S/H Circuit

This paper describes an 8-bit pipelined analog-to-digital converter (ADC) using a mixed-mode sample-and-hold (S/H) circuit at the front-end. The mixed-mode sampling technique reduces signal swings in pipelined ADCs while maintaining the signal-to-noise ratio. The reduction of signal swings relaxes the operational amplifier (opamp) gain, slew rate, bandwidth, and capacitor-matching requirements in pipelined ADCs. Due to the mixed-mode S/H technique, the single-stage opamps and small capacitor sizes can be used in this pipelined ADC, leading to a high speed and low-power consumption. Fabricated in a 0.18- $mu{hbox {m}}$ CMOS process, the 8-bit pipelined ADC consumes 22 mW with 1.8-V supply voltage. When sampling at 200 MSample/s, the prototype ADC achieves 54-dB spurious free dynamic range and 45-dB signal-to-noise and distortion ratio. The measured integral nonlinearity and differential nonlinearity are 0.34 LSB and 0.3 LSB, respectively.      

A 10-bit 50-MS/s sample-and-hold circuit with low distortion sampling switches

A fully-differential switched-capacitor sample-and-hold (S/H) circuit used in a 10-bit 50-MS/s pipeline analog-to-digital converter (ADC) was designed and fabricated using a 0.35-μm CMOS process. Capacitor fliparound architecture was used in the S/H circuit to lower the power consumption. In addition, a gain-boosted operational transconductance amplifier (OTA) was designed with a DC gain of 94 dB and a unit gain bandwidth of 460 MHz at a phase margin of 63 degree, which matches the S/H circuit. A novel double-side bootstrapped switch was used, improving the precision of the whole circuit. The measured results have shown that the S/H circuit reaches a spurious free dynamic range (SFDR) of 67 dB and a signal-to-noise ratio (SNR) of 62.1 dB for a 2.5 MHz input signal with 50 MS/s sampling rate. The 0.12 mm2 S/H circuit operates from a 3.3 V supply and consumes 13.6 mW.     

A 100-dB SFDR 80-MSPS 14-Bit 0.35-$ muhbox m$BiCMOS Pipeline ADC

This paper describes a 14-bit 80-MSPS ADC with 100-dB SFDR at 70-MHz input frequency in a 0.35-$muhbox m$single-well BiCMOS technology drawing 1.2 W from a dual 3.3 V/5.0 V supply. Key barriers to high dynamic range in pipeline ADCs at high clock rates and some methods to overcome these barriers will be presented. These methods include a sampling front-end without the use of a designated Sample and Hold (S/H). A BiCMOS switching input buffer is used along with the strategic use of BiCMOS design techniques. Also, calibration is combined with capacitor shuffling to maximize linearity with minimal noise impact.     

An 8-b 300MS/s folding and interpolating ADC for embedded applications

A 1.4-V 8-bit 300-MS/s folding and interpolating analog-to-digital converter (ADC) is proposed. Fabricated in the 0.13-μm CMOS process and occupying only 0.6-mm2 active area, the ADC is especially suitable for embedded applications. The system is optimized for a low-power purpose. Pipelining sampling switches help to cut down the extra power needed for complete settling. An averaging resistor array is placed between two folding stages for power-saving considerations. The converter achieves 43.4-dB signal-to-noise and distortion ratio and 53.3-dB spurious-free dynamic range at 1-MHz input and 42.1-dB and 49.5-dB for Nyquist input. Measured results show a power dissipation of 34 mW and a figure of merit of 1.14 pJ/convstep at 250-MHz sampling rate at 1.4-V supply.     

一种高速高精度采样/保持电路

介绍了一种用于12bit,100MS/s流水线模数转换器前端的采样/保持电路的设计.该电路在3V电源电压100MHz采样频率时,输入直到奈奎斯特频率仍能够达到108dB的无杂散动态范围(SFDR)和77dB的信躁比(SNR).论文建立了考虑开关之后的采样保持电路的分析模型,并详细研究了电路中开关组合对电路性能的影响,同时发现了传统的栅源自举开关(bootstrapped switch)中存在的漏电现象并对其进行了改进,极大地减小了漏电并提高了电路的线性性能.     

A Novel Low Power 1 GS/s S&H Architecture With Improved Analog Bandwidth

A new sample-and-hold (S&H) architecture is proposed for time-interleaved analog-to-digital converter (ADC). The use of this S&H circuit in front-end of a time-interleaved ADC system eliminates the need for sample-time calibration. Using the techniques of precharging and output capacitor coupling along with a new sampling technique called middle-plate-sampling can mitigate the stringent performance requirements for the opamp and sampling switches, resulting in low power consumption and allowing very high sampling rate. Simulated by HSPICE with a standard BSIM3v3 0.18 $mu{hbox{m}}$ technology, the S&H achieves 10-12 bits resolution for a 1.6-${hbox{V}}_{ rm{pp}}$ output at 1-GHz sampling rate. The S&H dissipates 12 mW from a 1.8-V supply.      

A 12-bit 1.0/2.0 GS/s Pipeline ADC in 0.18 µm SiGe BiCMOS

A 12-bit time-interleaved 1.0/2.0 GS/s pipeline analogue–digital converter (ADC) is presented and implemented in 0.18 µm SiGe BiCMOS. Such an ADC consists of two identical channels, each of which can operate at 1 GS/s. The two same channels can be interleaved to achieve 2 GS/s speed. In one-channel ADC, four lanes of pipeline ADCs with 250 MS/s are interleaved to realise 1 GHz conversion. To avoid the timing skew-induced error among the four lanes, a dedicated T/H is adopted in one channel. A clock buffer with low jitter is presented to provide a low-voltage swing clock for the T/H by using SiGe devices. The proposed timing system generates the phases needed accurately. A single reference buffer is employed in one-channel ADC to avoid the gain mismatches among the four lanes. An analogue mux with the proposed switch chooses the mode of interleaving or non-interleaving. A trimming digital–analogue converter is employed to eliminate the gain mismatches between the two channels. The measured SNDR and SFDR for one-channel ADC @ 1 GS/s are 60 and 76 dB with Nyquist input. For the interleaved two channels @ 2 GS/s, SNDR and SFDR can achieve 58 and 61 dB with Nyquist input.     

A 10-bit 50-MS/s subsampling pipelined ADC based on SMDAC and opamp sharing

This paper describes a 10-bit,50-MS/s pipelined A/D converter(ADC) with proposed area- and power-efficient architecture.The conventional dedicated sample-hold-amplifier(SHA) is eliminated and the matching requirement between the first multiplying digital-to-analog converter(MDAC) and sub-ADC is also avoided by using the SHA merged with the first MDAC(SMDAC) architecture,which features low power and stabilization.Further reduction of power and area is achieved by sharing an opamp between two successive pi...