In this paper, an analysis of the methodologies proposed in the past years to automate the synthesis of radio-frequency (RF) integrated circuit blocks is presented. In the light of this analysis, and to avoid nonsystematic iterations between sizing and layout design steps, a multiobjective optimization-based layout-aware sizing approach with preoptimized integrated inductor(s) design space is proposed. An automatic layout generation from netlist to ready-to-fabricate prototype is carried in-the-loop for each tentative sizing solution using an RF-specific module generator, template-based placer and evolutionary multinet router with preoptimized interconnect widths. The proposed approach exploits the full capabilities of the most established computer-aided design tools for RF design available nowadays, i.e., RF circuit simulator as performance evaluator, electromagnetic simulator for inductor characterization, and layout extractor to determine the complete circuit layout parasitics. Experiments are conducted over a widely used circuit in the RF context, showing the advantages of performing complete layout-aware sizing optimization from the very initial stages of the design process.

Journal Paper - IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, vol. 38, no. 6, pp 989-1002, 2019 IEEE
DOI: 10.1109/TCAD.2018.2834394    ISSN: 0278-0070    » doi

Random Telegraph Noise (RTN) has attracted increasing interest in the last years. This phenomenon introduces variability in the electrical properties of transistors, in particular in deeply-scaled CMOS technologies, which can cause performance degradation in circuits. In this work, the dependence of RTN parameters, namely current jump amplitude and emission and capture time constants, on the bias conditions, both V_G and V_D, has been studied on a set of devices, with a high granularity in a broad voltage range. The results obtained for the V_G dependences corroborate previous works, but suggest a unique trend for all the devices in a V_G range that goes from the near-threshold region up to voltages over the nominal operation bias. However, different trends have been observed in the parameters dependence for the case of V_D. From the experimental data, the probabilities of occupation of the associated defects have been evaluated, pointing out large device-to-device dispersion in the V_D dependences.

Journal Paper - Microelectronic Engineering, vol. 215, article 111004, 2019 ELSEVIER
DOI: 10.1016/j.mee.2019.111004    ISSN: 0167-9317    » doi

This special issue of the IEEE Transactions on Circuits and Systems-Part II: Express Briefs ( TCAS-II ) follows the successful co-publication initiative started last year by the IEEE Circuits and Systems Society (CASS) to publish a selection of the best papers accepted for presentation at the IEEE International Symposium on Circuits and Systems (ISCAS), held this year in Sapporo, Japan, on May 26-29. As TCAS-II only publishes five-page briefs, and hence both conference and journal versions of selected works would be largely overlapped, the papers included in this issue represent the only record published in IEEE Xplore and they will not appear in the Proceedings of IEEE ISCAS , which will however contain DOI links to the corresponding TCAS-II papers. Similar to other IEEE societies, IEEE-CASS intends to shift the role of IEEE conferences toward networking events as well as a scientific discussion opportunity, rather than putting the emphasis on the conference paper publication itself.

Journal Paper - IEEE Transactions on Circuits and Systems II: Express Briefs, vol. 66, no.5, pp 717-717, 2019 IEEE
DOI: 10.1109/TCSII.2019.2909179    ISSN: 1549-7747    » doi

Process variability and time-dependent variability have become major concerns in deeply-scaled technologies. Two of the most important time-dependent variability phenomena are Bias Temperature Instability (BTI) and Hot-Carrier Injection (HCI), which can critically shorten the lifetime of circuits. Both BTI and HCI reveal a discrete and stochastic behavior in the nanometer scale, and, while process variability has been extensively treated, there is a lack of design methodologies that address the joint impact of these two phenomena on circuits. In this work, an automated and timeefficient design methodology that takes into account both process and time-dependent variability is presented. This methodology is based on the utilization of lifetime-aware Pareto-Optimal Fronts (POFs). The POFs are generated with a multi-objective optimization algorithm linked to a stochastic simulator. Both the optimization algorithm and the simulator have been specifically tailored to reduce the computational cost of the accurate evaluation of the impact on a circuit of both sources of variability.

Conference - Design Automation and Test in Europe DATE 2019

Bias Temperature Instability has become a critical issue for circuit reliability. This phenomenon has been found to have a stochastic and discrete nature in nanometerscale CMOS technologies. To account for this random nature, massive experimental characterization is necessary so that the extracted model parameters are accurate enough. However, there is a lack of automated analysis tools for the extraction of the BTI parameters from the extensive amount of generated data in those massive characterization tests. In this paper, a novel algorithm that allows the precise and fully automated parameter extraction from experimental BTI recovery current traces is presented. This algorithm is based on the Maximum Likelihood Estimation principles, and is able to extract, in a robust and exact manner, the threshold voltage shifts and emission times associated to oxide trap emissions during BTI recovery, required to properly model the phenomenon.

Conference - Design Automation and Test in Europe DATE 2019