Stefano Pietri

A differential switched-capacitor amplifier with programmable gain and output offset voltage

The design of a low-power differential Switched-Capacitor (SC) amplifier for processing a fully-differential input signal coming from a pressure sensor interface is reported. The circuit is intended to amplify the input signal, convert it to single ended mode and shift its output by an offset voltage; gain and output offset voltage are digitally programmable. The differential SC amplifier employs an Operational Transconductance Amplifier (OTA) error cancellation technique without requiring its output to slew to analog ground each cycle. Circuit topology is very insensitive to low OTA gain and allows attaining 9-bit linearity. A SC Common-Mode Feedback (CMFB) configuration with symmetric loading of the differential mode loop has been adopted to reduce charge injection and leakage current errors, as well as to settle faster than traditional CMFB circuits. The circuit has been successfully integrated into a SoC device which measures pressure sensor pre-processed signal with a 10-bit Analog-to-Digital Converter (ADC). Implemented in a standard 4-metal single-poly 0.25um CMOS process, the module occupies a silicon area of 0.115 mm2, operates down to 1.8V and its 3-V typical current consumption is 40uA.

Power management controller for automotive MCU applications in 90nm CMOS technology

This paper describes the design and test of a Power Management Controller (PMC) for microcontroller unit (MCU) automotive applications in 90nm CMOS technology. The requirements for the PMC include a small, robust architecture with low I/O pin count and flexible extended features, no power sequence dependence and real-time monitoring of critical analog signals. The PMC contains circuitry to generate an internal 3.3V regulated supply voltage and to control the regulation of 1.2V supply with external NPN ballast transistor. It also comprises Low Voltage Detector (LVD) and Power-on Reset (POR) circuits for the 1.2V, 3.3V, 3.3V/5V supply of the closest I/O segment, and the unregulated 5V supply. A three way switch circuit is used to bias the N-well of both voltage regulators. This is required to guarantee correct bias and functioning over all start-up conditions and effective power down for both regulators. The circuit has been fabricated in 90nm CMOS technology and silicon results are provided.

An ultra low-power low-voltage programmable temperature detection circuit

The design of a low-power low-voltage programmable temperature detection circuit is described. The circuit provides a digital output that signals over-temperature and under- temperature conditions when die temperature rises above or falls below the programmed temperature thresholds. The output is obtained from the comparison between two temperature- related signals; the former has a CTAT with fixed thermal coefficient and the latter has an adjustable (PTAT, ZTAT or CTAT) thermal coefficient. The circuit design employs current as the main variable, based on the concept of inversion level. The circuit has been implemented in a 0.25μm standard CMOS process, operates down to 1.5V, occupies an area of 0.0235mm2, consumes 750nA including bias circuitry, and has ±5% accuracy for threshold temperatures ranging from -40°C to 150°C.

Safety oriented automotive MCU power management

The new generation of Power Management Controller (PMC) for Microcontroller Units (MCU) in the automotive application field is targeting increased modularity and flexibility of use, aiming to simplify board design and reduce external components as well as to reduce both development time and high volume production cost. A structural PMC design approach is followed by breaking the Intellectual Property (IP) system into several fundamental building blocks. Each block has a well defined set of features to cover the most demanding applications but allowing for scalability and flexible use, and speed up overall system design. In this paper we present a scalable architecture for a 5V PMC in CMOS 55nm technology. It includes a novel bandgap voltage reference with high noise immunity and improved curvature trimming based on bipolar ratio, a set of Low Voltage Detectors (LVDs) working sequentially during rising/falling supply edges, High Voltage Detectors (HVD), and an auxiliary back-up 1.2V regulator able to support fast load transitions, while the main 1.2V regulator is dedicated to supply most of the power consumption. The PMC IP has been integrated in automotive MCUs, with area from 0.6 to 1.2mm2, and Si results indicate modular architecture provides excellent trade-off among system complexity, power, wide safety specification features, low risk, and time to market.

A versatile low-dropout voltage regulator for automotive applications

In an effort to build versatile automotive Micro Controller Units (MCUs), power management has been integrated into the last generation SoC, with the additional benefits of simplifying board design and lowering the cost of bill of materials. In this paper we present a novel architecture for a 5 V to 3.3 V linear voltage regulator which can operate in dual mode: regulator controller, when an external ballast transistor is present; regulator mode, when a compensating capacitor is present. The circuit is being fabricated in CMOS 55 nm technology with non volatile memory process extension, occupies 0.05 mm2, and dissipates 1 mA current plus load.