An 11b 70-MHz 1.2-mm/sup 2/ 49-mW 0.18-/spl mu/m CMOS ADC with on-chip current/voltage references

This work proposes an 11b 70-MHz CMOS pipelined analog-digital converter (ADC) as one of core circuit blocks for very high speed digital subscriber line system applications. The proposed ADC for the internal use has the strictly limited number of externally connected I/O pins while the ADC employs on-chip CMOS current/voltage references and a merged-capacitor switching technique to improve ADC performances. The ADC implemented in a 0.18-/spl mu/m 1P4M CMOS technology shows the maximum signal-to-noise distortion ratio (SNDR) of 60 dB at 70 MSample/s. The ADC maintains the SNDR of 58 dB and the spurious-free dynamic resistance of 68 dB for input frequencies up to the Nyquist rate at 60 MSample/s. The measured differential and integral nonlinearities of the ADC are within /spl plusmn/0.63 and /spl plusmn/1.21 LSB, respectively. The active chip area is 1.2 mm/sup 2/ and the ADC consumes 49 mW at 70 MSample/s at 1.8 V.     

A 5-b 10-GSample/s a/D converter for 10-gb/s optical receivers

A 5-b flash A/D converter (ADC) is developed in an 0.18-/spl mu/m SiGe BiCMOS that supports sampling rates of 10 Gsample/s. The ADC is optimized to operate in digital equalizers for 10-Gb/s optical receivers, where the ADC has to deliver over three effective number of bits (ENOBs) at Nyquist. A fully differential flash ADC incorporating a wide-band track-and-hold amplifier (THA), a differential resistive ladder, an interpolation technique, and a high-speed comparator design is derived to resolve the aperture jitter and metastability error. The ADC achieves better than 4.1 effective bits for lower input frequencies and three effective bits for Nyquist input at 10 GS/s. The ADC dissipates about 3.6 W at the maximum clock rate of 10 GS/s while operating from dual -3.7/-3V supplies and occupies 3/spl times/3mm/sup 2/ of chip area.     

An 8/10 bit 200/100MS/s configurable asynchronous SAR ADC

This paper presents an asynchronous 8/10 bit configurable successive approximation register analog-to-digital converter (ADC). The proposed ADC has two resolution modes and can work at a maximal sampling rate of 200 and 100MS/s for 8 bit mode and 10 bit mode respectively. The ADC uses a custom-designed 1 fF unit capacitor to reduce the power consumption and settling time of capacitive DAC, a dynamic comparator with tail current to minimize kickback noise and improve linearity. Moreover, asynchronous control technique is utilized to implement the ADC in a flexible and energy-efficient way. The proposed ADC is designed in 90 nm CMOS technology. At 100MS/s and 1.0 V supply, the ADC consumes 1.06 mW and offers an ENOB of 9.56 bit for 10 bit mode. When the ADC operates at 8 bit mode, the sampling rate is 200MS/s with 1.56 mW power consumption from 1.0 supply. The resulted ENOB is 7.84 bit. The FOMs for 10 bit mode at 100MS/s and 8 bit mode at 200MS/s are 14 and 34 fJ/conversion-step respectively.     

A continuous-time /spl Sigma//spl Delta/ ADC with increased immunity to interferers

Receivers are being digitized in a quest for flexibility. Analog filters and programmable gain stages are being exchanged for digital processing at the price of a very challenging ADC. This paper presents an alternative solution where the filter and programmable gain functionality is integrated into a /spl Sigma//spl Delta/ ADC. The novel filtering ADC is realized by adding a high-pass feedback path to a conventional /spl Sigma//spl Delta/ ADC while a compensating low-pass filter in the forward path maintains stability. As such, the ADC becomes highly immune to interferers even if they exceed the maximum allowable input level for the wanted channel. As a consequence, the ADC input range can be programmed dynamically to the level of the wanted signal only. This results in an input-referred dynamic range of 89 dB in 1-MHz bandwidth and an intentionally moderate output signal-to-noise-and-distortion ratio of 46-59 dB (depending on the programmed gain). The merged functionality enables a better overall power/performance balance for the receiver baseband. The design consumes less than 2 mW and active area is 0.14 mm/sup 2/ in a 0.18-/spl mu/m digital CMOS technology.     

嵌入式折叠内插式CMOS模/数转换器设计

基于折叠内插式 ADC结构 ,采用分段式结构、两级折叠、主动内插技术和非线性误差补偿技术 ,采用TSMC0 .35 μm CMOS工艺设计实现了 8位 40 MS/s ADC。基于 BSIM3V3模型 ,采用 Cadence Spectre仿真器对 8位折叠内插式 ADC进行了系统仿真 ,采用 MPW计划对 ADC进行了流片验证 ,仿真和测试结果表明该ADC具有较低的非线性误差和良好的频域特性 ,证明了误差补偿技术的有效性。该 ADC的有效面积为 0 .6mm2 ,适合嵌入式应用。     

一种12位50MS/s CMOS流水线A/D转换器

采用TSMC 0.18μm 1P6M工艺设计了一个12位50 MS/s流水线A/D转换器（ADC）。为了减小失真和降低功耗,该ADC利用余量增益放大电路（MDAC）内建的采样保持功能,去掉了传统的前端采样保持电路;采用时间常数匹配技术,保证输入高频信号时,ADC依然能有较好的线性度;利用数字校正电路降低了ADC对比较器失调的敏感性。使用Cadence Spectre对电路进行仿真。结果表明,输入耐奎斯特频率的信号时,电路SNDR达到72.19 dB,SFDR达到88.23 dB。当输入频率为50 MHz的信号时,SFDR依然有80.51 dB。使用1.8 V电源电压供电,在50 MHz采样率下,ADC功耗为128 mW。     

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 9 b/12 b 50 MS/s experimental ADC with continuous approximation architecture in 65 nm CMOS

A 9 bits 50 MS/s 0.5 mW continuous approximation mixed successive approximation (CAR&SAR) ADC is presented. A 12 bits 50 MS/s 0.6 mW CAR&CAR ADC is presented. In the field of low power and high performance ADC, CAR is a new architecture different from SAR. It is faster and easier to get high accuracy. Here we will introduce CAR and its circuit implementation, and the 9 bits experimental ADC is designed to verify CARADC''s feasibility. Meanwhile, its resolution can be extended to 12 bits with adding an extra CAR, and then the performance is raised to 0.6 mW 50 MS/s 72 dB SNDR at TT corner and the Walden FOM is 3.6 fj/conv-step. The 9 b ADC was fabricated by using TSMC 1P9M 65 nm CMOS technology. The ADC achieves 50 dB SNDR and the realized Walden FOM is 34 fj/conv-step. The simulation and measurement results prove that CAR is available in the low power and high performance ADC and it even outperforms SAR. The ADC core occupies an active area of 0.045 mm².     

7位80MS/s电流模式折叠分级式模数转换器

提出了一种基于电流模式的折叠分级式A/D转换器(ADC),分析了电路原理和结构,阐述了如何提高ADC的性能。测试表明,电路已达到相关性能指标。转换速率为80MS/s,在3.0MHz输入信号下的信噪失真比(SINAD)为44.4dB,有效位数(ENOB)为7.1位。给出了已实现ADC电路的结构、测试波形和动态性能测试结果。     

A 6-Bit 1.6-GS/s Low-Power Wideband Flash ADC Converter in 0.13-$mu$ m CMOS Technology

In this work, a new termination technique for the averaging network of the flash analog-to-digital converter (ADC) input preamplifiers is devised. The proposed technique eliminates the over-range voltage headroom consumed by the dummy preamplifiers and therefore, the input capacitance and power dissipation of the ADC is reduced. This technique is applied to the design of a 6-bit 1.6-GS/s flash ADC in 0.13-$mu$ m CMOS technology. The measured peak INL and DNL are 0.42 LSB and 0.49 LSB, respectively. The ADC achieves an effective resolution bandwidth (ERBW) of 800 MHz and an SNDR of 30 dB at 1.45-GHz input signal frequency while consuming 180 mW.      

A 10-bit 5-MS/s successive approximation ADC cell used in a 70-MS/sADC array in 1.2-μm CMOS

A 10-bit 5-MS/s successive approximation ADC cell and a 70-MS/s parallel ADC array based on this cell, designed and fabricated in a 1.2-μm CMOS process, are presented. The ADC cell was designed to have an input bandwidth of more than 35 MHz and a sampling time of 14 nS at a clock rate of 70 MHz. The parallel ADC array consists of 14 such cells which are timed in one clock cycle skew successively in order to obtain digitized data every clock cycle. A two-step principle based on unsymmetrical dual-capacitor charge-redistribution-coupling has been used. With the help of a reset function, the comparator presents a fast response to the successive comparison. Each successive approximation ADC cell occupies an area of 0.6 mm² and the core of the parallel ADC array occupies an area of 2.7×3.3 mm². The power consumptions for the cell and the parallel ADC array are 18 mW and 267 mW respectively     

一种基于流水逐次逼近比较方式的模／数转换器

提出了一种新型模数转换方法——流水逐次逼近比较式模数转换法,并给出了相应的实验结果。在达到逐次逼近比较A/D转换器的相同转换时间tc的前提下,流水逐次逼近比较式A/D转换器的m和n函数关系等同于逐次逼近比较A/D转换器,而其tc和n的函数关系优于逐次逼近比较A/D转换器,并且比较流水式A/D转换器易于实现。     

一种40 MSPS 10位流水折叠分级式A/D转换器

探讨和研究基于流水线(Pipelined)技术的折叠分级式A/D转换器(ADC),理论分析了它的原理和一般结构,给出了一个具体结构的ADC框图和具体的折叠电路,并得出了实际制作的ADC的测试图。该折叠分级式ADC的输入频率可达到1 MHz,2级折叠电路产生的高2位加上子ADC产生的8位,使A/D转换器可达到10位的分辨率,采样率最大为40 MSPS。     

An 11-bit 200 MS/s subrange SAR ADC with low-cost integrated reference buffer

This paper presents an 11-bit 200 MS/s subrange SAR ADC with an integrated reference buffer in 65 nm CMOS. The proposed ADC employs a 3.5-bit flash ADC for coarse conversion, and a compact timing scheme at the flash/SAR boundary to speed up the conversion. The flash decision is used to control charge compensating for the reference voltage to reduce its input-dependent fluctuation. Measurement results show that the fabricated ADC has achieved significant improvement by applying the reference charge compensation. In addition, the ADC achieves a maximum signal-to-noise-and-distortion ratio of 59.3 dB at 200 MS/s. It consumes 3.91 mW from a 1.2 V supply, including the reference buffer.     

A 12-bit 200-MS/s pipelined A/D converter with sampling skew reduction technique

This paper presents a 12-bit 200-MS/s dual channel pipeline analog-to-digital converter (ADC). The ADC is featured with a digital timing correction for reducing a sampling skew and the capacitor swapping for suppressing nonlinearities at the first stage in the pipelined ADC. The prototype ADC occupies 0.8×1.4 mm² in a 65-nm CMOS technology. The differential nonlinearity is less than 1.0 least significant bit with a 200 MHz sampling frequency. With a sampling frequency of a 200-MS/s and an input of a 2.4 MHz, the ADC, respectively, achieves a signal to noise-and-distortion ratio and a spurious-free dynamic range of 61.49 dB–70.71 dB while consuming of 112 mW at a supply voltage of 1.1 V.     

An all-digital analog-to-digital converter with 12-/spl mu/V/LSB using moving-average filtering

A compact, high-resolution analog-to-digital converter (ADC) especially for sensors is presented. The basic structure is a completely digital circuit including a ring-delay-line with delay units (DUs), along with a frequency counter, latch, and encoder. The operating principles are: (1) the delay time of the DU is modulated by the analog-to-digital (A/D) conversion voltage and (2) the delay pulse passes through a number of DUs within a sampling (= integration) time and the number of DUs through which the delay pulse passes is output as conversion data. Compact size and high resolution were realized with an ADC having a circuit area of 0.45 mm/sup 2/ (0.8-/spl mu/m CMOS) and a resolution of 12 /spl mu/V (10 kS/s). Its nonlinearity is /spl plusmn/0.1% FS per 200-mV span (1.8-2.0 V), for 14-b resolution. Sample holds are unnecessary and a low-pass filter function removes high-frequency noise simultaneously with A/D conversion. Thus, the combination of this ADC and a digital filter that follows can eliminate an analog prefilter to prevent the aliasing before A/D conversion. Also, both this ADC can be shrunk and operated at low voltages, so it is an ideal means to lower the cost and power consumption. Drift errors can be easily compensated for by digital processing.     

A 65-fJ/Conversion-Step 0.9-V 200-kS/s Rail-to-Rail 8-bit Successive Approximation ADC

An 8-bit successive approximation (SA) analog-to- digital converter (ADC) in 0.18 mum CMOS dedicated for energy-limited applications is presented. The SA ADC achieves a wide effective resolution bandwidth (ERBW) by applying only one bootstrapped switch, thereby preserving the desired low power characteristic. Measurement results show that at a supply voltage of 0.9 V and an output rate of 200 kS/s, the SA ADC performs a peak signal-to-noise-and-distortion ratio of 47.4 dB and an ERBW up to its Nyquist bandwidth (100 kHz). It consumes 2.47 muW in the test, corresponding to a figure of merit of 65 f J/conversion-step.     

A 12-b, 60-MSample/s cascaded folding and interpolating ADC

This paper describes the analysis, design, and experimental results of a 12-b, 60-MSample/s analog-to-digital converter (ADC). This ADC is based on a cascaded folding and interpolating architecture. The ADC is optimized for digital telecommunication applications. The cascaded folding and interpolating ADC architecture is introduced, optimizing the overall performance of this converter. The integrated track and hold amplifier enables an SNR>66 dB and a THD<72 dB, measured over an analog input signal bandwidth of 70 MHz. The ADC is realized in a 13-GHz, 1-μm BiCMOS process and measures 7 mm² , while dissipating 300 mW from a single 5.0 V supply     

A 6-b, 4 GSa/s GaAs HBT ADC

A GaAs-AlGaAs heterojunction bipolar transistor (HBT) process was developed to meet the speed, gain, and yield requirements for analog-to-digital converters (ADC's). The HBT has current gain of over 100 and f_T and f_MAX of over 50 GHz. A 6-b, 4 GSa/s (4 giga-samples/s) ADC was designed and fabricated in this process. The ADC uses an analog folding architecture, includes an on-chip master-slave track-and-hold (T/H) circuit, and provides Gray-encoded digital outputs. The ADC achieves 5.6 effective bits at 4 GSa/s, a faster clock rate than any noninterleaved semiconductor ADC reported to date. It has a resolution bandwidth (the frequency at which effective bits has dropped by 0.5 b) of 1.8 GHz at 4 GSa/s, higher than any published ADC. The chip operates at up to 6.5 GSa/s. GaAs HBT IC's are especially prone to high operating temperatures. This led to reliability problems that were overcome by the use of a fast DC thermal simulator written for this project. A SPICE model for self-heating effects is also described     

采用改进型1.5位/级结构的10位100MHz流水线模数转换器

介绍了一个采用改进型1.5位/级结构的10位100MHz流水线结构模数转换器.测试结果表明,模数转换器的信噪失真比最高可以达到57dB,在100MHz输入时钟下,输入信号为57MHz的奈奎斯特频率时,信噪失真比仍然可以达到51dB.模数转换器的差分非线性和积分非线性分别为0.3LSB和1.0LSB.电路采用0.18μm混合信号CMOS工艺实现,芯片面积为0.76mm2.