Single-MOSFET DC thermal sensor for RF-amplifier central frequency extraction

© 2017 Elsevier B.V. A DC thermal sensor based on a single metal-oxide-semiconductor field-effect transistor (MOSFET) is proposed to extract high-frequency electrical features of embedded circuits. The MOSFET sensor is monolithically integrated with the circuit under test (CUT) and then monitors by thermal means the DC power dissipated by the CUT, which carries high-frequency electrical information. After explaining the theory behind this testing approach, the paper demonstrates the feasibility of the proposed MOSFET sensor through simulations and experiments. These are carried out using a radio-frequency (RF) power amplifier as a CUT and thermally extracting its central frequency (440 MHz). The MOSFET sensor results are assessed using an infrared camera as a reference. The main advantage of the proposed sensing method is that the impact on the integrated circuit (IC) layout area is minimum, which is crucial when testing RF-ICs. Moreover, in comparison with previous works, the cost and complexity of the required instrumentation is lower.Postprint (author's final draft

MOSFET dynamic thermal sensor for IC testing applications

This paper analyses how a single metal-oxide-semiconductor field-effect transistor (MOSFET) can be employed as a thermal sensor to measure on-chip dynamic thermal signals caused by a power-dissipating circuit under test (CUT). The measurement is subjected to two low-pass filters (LPF). The first LPF depends on the thermal properties of the heat-conduction medium (i.e. silicon) and the CUT-sensor distance, whereas the second depends on the electrical properties of the sensing circuit such as the bias current and the dimensions of the MOSFET sensor. This is evaluated along the paper through theoretical models, simulations, and experimental data resulting from a chip fabricated in 0.35 mu m CMOS technology. Finally, the proposed thermal sensor and the knowledge extracted from this paper are applied to estimate the linearity of a radio-frequency (RF) amplifier. (C) 2016 Elsevier B.V. All rights reserved.Peer ReviewedPostprint (author's final draft

BPF-based thermal sensor circuit for on-chip testing of RF circuits

A new sensor topology meant to extract figures of merit of radio-frequency analog integrated circuits (RF-ICs) was experimentally validated. Implemented in a standard 0.35 µm complementary metal-oxide-semiconductor (CMOS) technology, it comprised two blocks: a single metaloxide-semiconductor (MOS) transistor acting as temperature transducer, which was placed near the circuit to monitor, and an active band-pass filter amplifier. For validation purposes, the temperature sensor was integrated with a tuned radio-frequency power amplifier (420 MHz) and MOS transistors acting as controllable dissipating devices. First, using the MOS dissipating devices, the performance and limitations of the different blocks that constitute the temperature sensor were characterized. Second, by using the heterodyne technique (applying two nearby tones) to the power amplifier (PA) and connecting the sensor output voltage to a low-cost AC voltmeter, the PA’s output power and its central frequency were monitored. As a result, this topology resulted in a low-cost approach, with high linearity and sensitivity, for RF-IC testing and variability monitoring.This research was funded by Spanish AEI–Agencia Estatal de Investigación–grant number PID2019-103869RB-C33. (X.P.) has also received founds from the Spanish Ministry of Science, Innovation and Universities through Agencia Estatal de Investigación (AEI) (projects: HIPERCELLS, RTI2018-098392B-I00, and “Fiabilidad Inteligente”, PCI2020-112028).Peer ReviewedPostprint (published version

Study of heat sources interacting in integrated circuits by laser mirage effect

This work exploits the mirage effect to analyze multiple heat sources thermally interacting in an integrated circuit (IC) by means of a probe IR laser beam, which strikes on the die lateral walls and passes through the die substrate. Under such conditions, the criteria for locating such hot spots, as well as their relative power dissipation, are discussed on the basis of a theoretical model inferred in this work. Finally, the technique feasibility is shown in a real application scenario, obtaining 5-mu m spatial lateral resolution and an error in power dissipation measurements below 5%. This method may become a practical alternative to usual off-chip techniques for inspecting hot spots in ICs and to experimentally characterize heat flow in the semiconductor substrate. (C) 2014 AIP Publishing LLC.Peer Reviewe

Study of heat sources interacting in integrated circuits by laser mirage effect

This work exploits the mirage effect to analyze multiple heat sources thermally interacting in an integrated circuit (IC) by means of a probe IR laser beam, which strikes on the die lateral walls and passes through the die substrate. Under such conditions, the criteria for locating such hot spots, as well as their relative power dissipation, are discussed on the basis of a theoretical model inferred in this work. Finally, the technique feasibility is shown in a real application scenario, obtaining 5-mu m spatial lateral resolution and an error in power dissipation measurements below 5%. This method may become a practical alternative to usual off-chip techniques for inspecting hot spots in ICs and to experimentally characterize heat flow in the semiconductor substrate. (C) 2014 AIP Publishing LLC.Peer Reviewe

Thermal phase lag heterodyne infrared imaging for current tracking in radio frequency integrated circuits

With thermal phase lag measurements, current paths are tracked in a Class A radio frequency (RF) power amplifier at 2 GHz. The amplifier is heterodynally driven at 440 MHz and 2 GHz, and its resulting thermal field was inspected, respectively, at 1013 and 113 Hz with an infrared lock-in thermography system. The phase lag maps evidence with a higher sensitivity than thermal amplitude measurements an input-output loop due to a substrate capacitive coupling. This limits the amplifier’s performance, raising the power consumption in certain components. Other information relative to local power consumption and amplifier operation is also inferred. This approach allows the local non-invasive testing of integrated systems regardless of their operating frequency.Peer Reviewe

Thermal phase lag heterodyne infrared imaging for current tracking in radio frequency integrated circuits

With thermal phase lag measurements, current paths are tracked in a Class A radio frequency (RF) power amplifier at 2 GHz. The amplifier is heterodynally driven at 440 MHz and 2 GHz, and its resulting thermal field was inspected, respectively, at 1013 and 113 Hz with an infrared lock-in thermography system. The phase lag maps evidence with a higher sensitivity than thermal amplitude measurements an input-output loop due to a substrate capacitive coupling. This limits the amplifier’s performance, raising the power consumption in certain components. Other information relative to local power consumption and amplifier operation is also inferred. This approach allows the local non-invasive testing of integrated systems regardless of their operating frequency.Peer Reviewe

MOSFET dynamic thermal sensor for IC testing applications

This paper analyses how a single metal-oxide-semiconductor field-effect transistor (MOSFET) can be employed as a thermal sensor to measure on-chip dynamic thermal signals caused by a power-dissipating circuit under test (CUT). The measurement is subjected to two low-pass filters (LPF). The first LPF depends on the thermal properties of the heat-conduction medium (i.e. silicon) and the CUT-sensor distance, whereas the second depends on the electrical properties of the sensing circuit such as the bias current and the dimensions of the MOSFET sensor. This is evaluated along the paper through theoretical models, simulations, and experimental data resulting from a chip fabricated in 0.35 mu m CMOS technology. Finally, the proposed thermal sensor and the knowledge extracted from this paper are applied to estimate the linearity of a radio-frequency (RF) amplifier. (C) 2016 Elsevier B.V. All rights reserved.Peer Reviewe

Temperature sensors and measurements to test analogue circuits: questions and answers

We have been working in the field of temperature sensors and temperature measurements to test analogue circuits during the past 10 years. As we have presented different works in many conferences, we have collected many interesting questions, some of them collected more than once!. Here you have some of them. Our goal in this paper is to introduce temperature measurements and temperature sensors to test analog circuits from the highest level of abstraction. This paper has been written with the goal to provide basic understanding and present some of the possibilities of temperature sensors and measurements to test integrated circuits in general, analog in particular.Peer ReviewedPostprint (published version

Single-MOSFET DC thermal sensor for RF-amplifier central frequency extraction

© 2017 Elsevier B.V. A DC thermal sensor based on a single metal-oxide-semiconductor field-effect transistor (MOSFET) is proposed to extract high-frequency electrical features of embedded circuits. The MOSFET sensor is monolithically integrated with the circuit under test (CUT) and then monitors by thermal means the DC power dissipated by the CUT, which carries high-frequency electrical information. After explaining the theory behind this testing approach, the paper demonstrates the feasibility of the proposed MOSFET sensor through simulations and experiments. These are carried out using a radio-frequency (RF) power amplifier as a CUT and thermally extracting its central frequency (440 MHz). The MOSFET sensor results are assessed using an infrared camera as a reference. The main advantage of the proposed sensing method is that the impact on the integrated circuit (IC) layout area is minimum, which is crucial when testing RF-ICs. Moreover, in comparison with previous works, the cost and complexity of the required instrumentation is lower