A Subthreshold SCL Based Pipelined Encoder for Ultra-Low Power 8-bit Folding/Interpolating ADC

The subthreshold MOS source-coupled logic (STSCL) technique is of great interest for designing ultra low power circuits. In this paper we discuss the design of a pipelined encoder for an 8-bit folding and interpolating (F&I) analog-to-digital (ADC) data converter using this technique. The encoder is designed and characterized in a conventional 0.18μm CMOS technology, and it is capable of operating over a wide frequency range (10kHz-50MHz) without the need of resizing the transistors or scaling the voltage levels. The speed and power consumption of the encoder are proportional to the bias currents of the gates. The supply voltage of the circuit can be as low as 350mV

Delay models and design guidelines for MCML gates with resistor or PMOS load

In this paper we present propagation delay models for MCML gates with resistor- or triode-PMOS-based output I–V conversion. The dependence of the parasitic capacitance of triode PMOS devices is accurately evaluated for the first time in the literature. The proposed models are able to accurately predict the propagation delay as a function of the bias current ISS in different design scenarios which require different tradeoffs between speed, area and power efficiency. The proposed models are validated against transistor level simulations referring to a 28 ​nm CMOS process showing a maximum percentage error lower than 6.5%. Based on these models, a comparative analysis is carried out and useful guidelines for the design of MCML gates are proposed

On low-power analog implementations of particle filters for target tracking

We propose a low-power, analog and mixed-mode, implementation of particle filters. Low-power analog implementation of nonlinear functions such as exponential and arctangent functions is done using multiple-input translinear element (MITE) networks. These nonlinear functions are used to calculate the probability densities in the particle filter. A bearings-only tracking problem is simulated to present the proposed low-power implementation of the particle filter algorithm

MCML D-Latch Using Triple-Tail Cells: Analysis and Design

A new low-voltage MOS current mode logic (MCML) topology for D-latch is proposed. The new topology employs a triple-tail cell to lower the supply voltage requirement in comparison to traditional MCML D-latch. The design of the proposed MCML D-latch is carried out through analytical modeling of its static parameters. The delay is expressed in terms of the bias current and the voltage swing so that it can be traded off with the power consumption. The proposed low-voltage MCML D-latch is analyzed for the two design cases, namely, high-speed and power-efficient, and the performance is compared with the traditional MCML D-latch for each design case. The theoretical propositions are validated through extensive SPICE simulations using TSMC 0.18 µm CMOS technology parameters

A methodology for automated design and implementation of complex analog and digital CMOS integrated circuits applying a genetic algorithm and a CAD tool for multiobjective optimization.

Tesis (Doctorado en Ciencias Naturales para el Desarrollo) Instituto Tecnológico de Costa Rica, Escuela de Ingeniería Electrónica, 2014.This dissertation proposes an automated methodology to design and optimize electronic integrated circuits, something that could be called simulation-driven optimization. The concept of Pareto optimality or the so called Pareto front is introduced as a useful analysis tool in order to explore the design space of such circuits. A genetic algorithm (GA) is employed to automatically detect this front in a process that efficiently finds optimal parameterizations and their corresponding values in an aggregate fitness space. Since the problem at hand is inherently a multi-objective optimization task, many different performance measures of the circuits must be able to be easily defined and computed as fitness functions. The methodology has been validated through measurements of several fabricated test cases, using MOSIS fabrication services for a standard 0.5m CMOS technology.Instituto Tecnológico de Costa Rica. Escuela de Ingeniería Electrónica

Circuitos digitais em modo de corrente

Mestrado em Engenharia Electrónica e TelecomunicaçõesEste trabalho de dissertação insere-se na área da electrónica digital, e consiste no projecto, construção e caracterização de circuitos digitais em Modo de Corrente, empregando estratégias de desenho MCML (MOS Current Mode Logic). Circuitos MCML apresentam como principais vantagens um bom compromisso entre o analógico e digital e potência dissipada constante, sendo desta forma uma boa solução para aplicações que exigem altas velocidades de operação. Neste trabalho são abordadas as principais características da lógica MCML relativas ao projecto de circuitos digitais através de uma análise detalhada do inversor MCML. É ainda efectuada uma abordagem sobre as metodologias para implementação/desenho das principais funções lógicas, bem como uma análise comparativa das suas características. Posteriormente implementa-se um conjunto de portas lógicas, analisando as diferentes topologias provenientes do método de implementação adoptado. Para analisar o desempenho de circuitos MCML, projectou-se algumas funções lógicas, em tecnologia CMOS 350nm da AMS, procedendo à sua simulação e caracterização.The present dissertation is inserted in the general subject of digital electronics, and discusses the design, layout and characterization of current-mode digital circuits using MCML design strategies. MCML circuits exhibit major advantages in digital design, like a constant power consumption, and present a good compromise for analog and digital applications. This work addresses the most important characteristics of MCML logic for the design of digital circuitry through a detailed analysis of the MCML inverter. The basic methodologies used for implementation/layout of the most important logical functions are assessed, and a comparative analysis of their characteristics is performed. Further on, the set of logic gates designed in the course of this work is presented, allowing for the analysis of different topologies from the chosen implementation methodology. Finally, in order to analyze the performance of MCML circuits, several logic functions where implemented using the AMS 350nm CMOS technology. The respective characterization and simulation results are presented and discussed

A Low Jitter Analog Circuit for Precisely Correcting Timing Skews in Time Interleaved Analog-to-Digital Converters

Time-interleaved analog-to-digital converters are an attractive architecture for achieving a high speed, high resolution ADC in a power efficient manner. However, due to process and manufacturing variations, timing skews occur between the sampling clocks of the sub ADCs within the TI-ADC. These timing skews compromise the spurious free dynamic range of the converter. In addition, jitter on the sampling clocks, degrades the signal-to-noise ratio of the TI-ADC. Therefore, in order to maintain an acceptable spurious free dynamic range and signal to noise ratio, it is necessary to correct the timing skews while adding minimal jitter. Two analog-based architectures for correcting timing skews were investigated, with one being selected for implementation. The selected architecture and additional test circuitry were designed and fabricated in a 0.18µm CMOS process and tested using a 125 MSPS 16 bit ADC. The circuit achieves a correction precision on the order of 10’s of femtoseconds for timing skews as large as approximately 180 picoseconds, while adding less than 200 femtoseconds of rms jitter

Design and modelling of clock and data recovery integrated circuit in 130 nm CMOS technology for 10 Gb/s serial data communications

This thesis describes the design and implementation of a fully monolithic 10 Gb/s phase and frequency-locked loop based clock and data recovery (PFLL-CDR) integrated circuit, as well as the Verilog-A modeling of an asynchronous serial link based chip to chip communication system incorporating the proposed concept. The proposed design was implemented and fabricated using the 130 nm CMOS technology offered by UMC (United Microelectronics Corporation). Different PLL-based CDR circuits topologies were investigated in terms of architecture and speed. Based on the investigation, we proposed a new concept of quarter-rate (i.e. the clocking speed in the circuit is 2.5 GHz for 10 Gb/s data rate) and dual-loop topology which consists of phase-locked and frequency-locked loop. The frequency-locked loop (FLL) operates independently from the phase-locked loop (PLL), and has a highly-desired feature that once the proper frequency has been acquired, the FLL is automatically disabled and the PLL will take over to adjust the clock edges approximately in the middle of the incoming data bits for proper sampling. Another important feature of the proposed quarter-rate concept is the inherent 1-to-4 demultiplexing of the input serial data stream. A new quarter-rate phase detector based on the non-linear early-late phase detector concept has been used to achieve the multi-Giga bit/s speed and to eliminate the need of the front-end data pre-processing (edge detecting) units usually associated with the conventional CDR circuits. An eight-stage differential ring oscillator running at 2.5 GHz frequency center was used for the voltage-controlled oscillator (VCO) to generate low-jitter multi-phase clock signals. The transistor level simulation results demonstrated excellent performances in term of locking speed and power consumption. In order to verify the accuracy of the proposed quarter-rate concept, a clockless asynchronous serial link incorporating the proposed concept and communicating two chips at 10 Gb/s has been modelled at gate level using the Verilog-A language and time-domain simulated