An experimental technique is described for observing the effects of switching transients in digital MOS circuits that perturb analog circuits integrated on the same die by means of coupling through the substrate Various approaches to reducing substrate crosstalk (the use of physical separation of analog and digital circuits, guard rings, and a low-inductance substrate bias) are evaluated experimentally for a CMOS technology with a substrate comprising an epitaxial layer grown on a heavily doped bulk wafer Observations indicate that reducing the inductance in the substrate bias is the most effective Device simulations are used to show how crosstalk propagates via the heavily doped bulk and to predict the nature of substrate crosstalk in CMOS technologies integrated in uniform, lightly doped bulk substrates, showing that in such cases the substrate noise is highly dependent on layout geometry A method of including substrate effects in SPICE simulations for circuits fabricated on epitaxial, heavily doped substrates is developed >

Experimental Results and Modeling Techniques for Substrate Noise in Mixed-Signal Integrated Circuits

In this paper key design issues and considerations of a low-cost 3-D Cu-TSV technology are investigated. The impact of TSV on BEOL interconnect reliability is limited, no failures have been observed. The impact of TSV stress on MOS devices causes shifts, further analysis is required to understand their importance. Thermal hot spots in 3-D chip stacks cause temperature increases three times higher than in 2-D chips, necessitating a careful thermal floorplanning to avoid thermal failures. We have monitored for ESD during 3-D processing and have found no events take place, however careful further monitoring is required. The noise coupling between two tiers in a 3-D chip-stack is 20 dB lower than in a 2-D SoC, opening opportunities for increased mixed signal system performance. The impact on digital circuit performance of TSVs is accurately modeled with the presented RC model and digital gates can directly drive signals through TSVs at high speed and low power. Experimental results of a 3-D Network-on-Chip implementation demonstrate that the NoC concept can be extended from 2-D SoC to 3-D SoCs at low area (0.018 ) and power (3%) overhead.

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Design Issues and Considerations for Low-Cost 3-D TSV IC Technology

This paper presents a tutorial overview of ΣΔ modulators, their operating principles and architectures, circuit errors and models, design methods, and practical issues. A review of the state of the art on nanometer CMOS implementations is described, giving a survey of cutting-edge ΣΔ architectures, with emphasis on their application to the next generation of wireless telecom systems.

Sigma-Delta Modulators: Tutorial Overview, Design Guide, and State-of-the-Art Survey

This paper presents a MUlti-SEnsor biomedical IC (MUSEIC). It features a high-performance, low-power analog front-end (AFE) and fully integrated DSP. The AFE has three biopotential readouts, one bio-impedance readout, and support for general-purpose analog sensors The biopotential readout channels can handle large differential electrode offsets ( ${\pm} $ 400 mV), achieve high input impedance ( ${>}$ 500 M $\Omega$ ), low noise ( ${ 620 nVrms in 150 Hz), and large CMRR ( ${>}$ 110 dB) without relying on trimming while consuming only 31 $\mu$ W/channel. In addition, fully integrated real-time motion artifact reduction, based on simultaneous electrode-tissue impedance measurement, with feedback to the analog domain is supported. The bio-impedance readout with pseudo-sine current generator achieves a resolution of 9.8 m $\Omega$ / $\surd$ Hz while consuming just 58 $\mu$ W/channel. The DSP has a general purpose ARM Cortex M0 processor and an HW accelerator optimized for energy-efficient execution of various biomedical signal processing algorithms achieving 10 $\times$ or more energy savings in vector multiply-accumulate executions.

A 345 µW Multi-Sensor Biomedical SoC With Bio-Impedance, 3-Channel ECG, Motion Artifact Reduction, and Integrated DSP

An overview of through-silicon-via technology and manufacturing challenges

Wireless environments, high data rates and increased digitization require A/D converters with high dynamic range and large bandwidth at the lowest possible power consumption. A fully flexible continuous-time (CT) Δ Σ with programmable bandwidth, resolution and power consumption in 1.2 V 90 nm CMOS is presented able to satisfy those demands. By introducing flexibility into the core building blocks, a DR of 67/72/78/83 dB is achieved in maximum performance mode for WLAN, DVB, UMTS and BT for a power consumption of 6.8/5.5/6.4/5.0 mW, respectively. GSM operation is also feasible with a DR of 87 dB. For a given bandwidth, the flexibility allows to obtain the lowest power consumption for a desired performance. The overall energy efficiency is reached with a single-bit CT Δ Σ modulator avoiding high speed DEM circuits. Its low power consumption especially for high bandwidths is realized thanks to architecture and circuit level optimization. Linearity enhanced integrators, a threshold configurable comparator enabling loop delay compensation and optimized DAC implementations for jitter and avoiding signal dependency in the feedback pulses due to a large voltage swing are employed to increase the performance. The respective FOM equals 0.24/0.27/0.41/0.85 pJ per conversion.

A Single-Bit 500 kHz-10 MHz Multimode Power-Performance Scalable 83-to-67 dB DR CTΔΣ for SDR in 90 nm Digital CMOS

Communication in the unlicensed frequency band around 60GHz requires a very fast ADC with low resolution. We present a four-way interleaved converter, of which one channel is shown in Fig. 16.3.1, for these requirements. Dynamic pipelined conversion enables low power quantization at high speed with low input capacitance but requires calibration. A folding front-end halves the required calibration effort.

A 2.6mW 6b 2.2GS/s 4-times interleaved fully dynamic pipelined ADC in 40nm digital CMOS

This paper shows that multirate processing in a cascaded discrete-time ΔΣ modulator allows to reduce the power consumption by up to 35%. Multirate processing is possible in a discrete-time ΔΣ modulator by its adaptibility with the sampling frequency. The power reduction can be achieved by relaxing the sampling speed of the first stage and increasing it appropriately in the second stage. Furthermore, a cascaded ΔΣ modulator enables the power efficient implementation of multiple communication standards.@The advantages of multirate cascaded ΔΣ modulators are demonstrated by comparing the performance of single-rate and multirate implementations using behavioral-level and circuit-level simulations. This analysis has been further validated with the design of a multirate cascaded triple-mode discrete-time ΔΣ modulator. A 2-1 multirate low-pass cascade, with a sampling frequency of 80 MHz in the first stage and 320 MHz in the second stage, meets the requirements for UMTS. The first stage alone is suitable for digitizing Bluetooth and GSM with a sampling frequency of 90 and 50 MHz respectively. This multimode ΔΣ modulator is implemented in a 1.2 V 90 nm CMOS technology with a core area of 0.076 mm2. Measurement results show a dynamic range of 66/77/85 dB for UMTS/ Bluetooth/GSM with a power consumption of 6.8/3.7/3.4 mW. This results in an energy per conversion step of 1.2/0.74/2.86 pJ.

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Multirate Cascaded Discrete-Time Low-Pass ΔΣ Modulator for GSM/Bluetooth/UMTS

A 2.2 GS/s 4×-interleaved 6b ADC in 40 nm digital CMOS is presented. Each ADC slice consists of a 1b folding stage followed by a pipelined binary-search sub-ADC using dynamic nonlinear amplifiers for low power consumption and high speed. The folding stage samples the input, removes its common-mode component and rectifies the differential voltage. The pipelined binary-search sub-ADC leverages threshold calibration to correct for amplifier and comparator imperfections, which allows the use of inherently nonlinear dynamic amplifiers. The prototype achieves 31.6 dB SNDR at 2.2 GS/s with a 2 GHz ERBW for 2.6 mW power consumption in an area of 0.03 mm2.

A 2.6 mW 6 bit 2.2 GS/s Fully Dynamic Pipeline ADC in 40 nm Digital CMOS

A 0.4mm2 low-power fully-reconfigurable continuous-time (CT) feedforward ΔΣ ADC for 4G radios is implemented in 90nm CMOS. By reconfiguring the topology architecture, quantizer bits, biasing current and component parameters, optimal power consumption can be achieved for every mode. The modulator achieves a DR of 85/78/76/72/58dB for GSM/BT/UMTS/DVB-H/WLAN with 2.8/2.6/3.6/4.9/8.5mW from 1V supply. The FOM is 0.68/0.5/0.28/0.27/0.41pJ/conv.

Geert Van der Plas

Papers

A Single-Bit 500 kHz-10 MHz Multimode Power-Performance Scalable 83-to-67 dB DR CTΔΣ for SDR in 90 nm Digital CMOS

A 2.6mW 6b 2.2GS/s 4-times interleaved fully dynamic pipelined ADC in 40nm digital CMOS

Multirate Cascaded Discrete-Time Low-Pass ΔΣ Modulator for GSM/Bluetooth/UMTS

A 2.6 mW 6 bit 2.2 GS/s Fully Dynamic Pipeline ADC in 40 nm Digital CMOS

A 2.8-to-8.5mW GSM/bluetooth/UMTS/DVB-H/WLAN fully reconfigurable CTΔΣ with 200kHz to 20MHz BW for 4G radios in 90nm digital CMOS