Didac Gómez

Process and Temperature Compensation for RF Low-Noise Amplifiers and Mixers

Temperature and process variations have become key issues in the design of integrated circuits using deep submicron technologies. In RF front-end circuitry, many characteristics must be compensated in order to maintain acceptable performance across all process corners and throughout the temperature range. This paper proposes a new technique consisting of a compensation circuit that adapts and generates the appropriate bias voltage for LNAs and mixers so that the variability with temperature and process corners of their main performance metrics (S-parameters, gain, noise figure, etc.) is minimized.

On-Chip MOSFET Temperature Sensor for Electrical Characterization of RF Circuits

This letter proposes a new sensor circuit to measure on-chip low-frequency temperature changes that have information about electrical high-frequency figures of merit of a radio frequency (RF) circuit. The proposed sensor circuit uses a metal-oxide-semiconductor field-effect transistor (MOSFET) as a temperature sensing device, which is then connected to a band-pass filter that amplifies the low-frequency temperature signal generated by the RF circuit under test (CUT). Simulations in 65 nm CMOS technology show that such a sensor circuit can extract the center frequency (2.47 GHz) of a RF power amplifier (PA) by measuring on-chip temperature changes at 1 kHz.

DC temperature measurements for power gain monitoring in RF power amplifiers

In this paper we demonstrate that the steady state temperature increase due to the power dissipated by the circuit under test can be used as observable to test the gain of a 2GHz linear class A Power Amplifier. As a proof of concept, we use two strategies to monitor the temperature: a temperature sensor embedded within the same silicon die, which can be used for a BIST approach, and an Infra Red camera, with applications to failure analysis and product debugging.

Survey of Robustness Enhancement Techniques for Wireless Systems-on-a-Chip and Study of Temperature as Observable for Process Variations

Built-in test and on-chip calibration features are becoming essential for reliable wireless connectivity of next generation devices suffering from increasing process variations in CMOS technologies. This paper contains an overview of contemporary self-test and performance enhancement strategies for single-chip transceivers. In general, a trend has emerged to combine several techniques involving process variability monitoring, digital calibration, and tuning of analog circuits. Special attention is directed towards the investigation of temperature as an observable for process variations, given that thermal coupling through the silicon substrate has recently been demonstrated as mechanism to monitor the performances of analog circuits. Both Monte Carlo simulations and experimental results are presented in this paper to show that circuit-level specifications exhibit correlations with silicon surface temperature changes. Since temperature changes can be measured with efficient on-chip differential temperature sensors, a conceptual outline is given for the use of temperature sensors as alternative process variation monitors.

On the Use of Static Temperature Measurements as Process Variation Observable

In this paper we present the use of static temperature measurements as process variation observable. Contrary to previously published thermal testing methods, the proposed methodology does not need an excitation signal, thus reducing test cost and improving built-in capabilities of thermal monitoring. The feasibility of the technique and a complete test methodology is presented using a narrowband LNA as example. Finally, a complete electro-thermal co-simulation test bench between the LNA and a differential temperature sensor embedded in the same silicon die is presented in order to validate the results. Results prove that RF figures of merit can be extracted from DC temperature measurements done without loading or exciting the RF circuit under test.

A 75 pJ/bit all-digital quadrature coherent IR-UWB transceiver in 0.18 µm CMOS

In this paper a 75 pJ/b all-digital quadrature coherent impulse radio ultra-wideband transceiver in 0.18 μm CMOS is presented. It consumes 42 mW operating at a 560 Mbps datarate. The receiver and transmitter share most of the components reducing the area. This design is optimal for low-power low-cost short-range high-speed communications.

A low-power RF front-end for 2.5 GHz receivers

This paper presents a low power and low cost front end for a direct conversion 2.5 GHz ISM band receiver composed of a 16 kV HBM ESD protected LNA, differential Gilbert-cell mixers, and high-pass filters for DC offset cancellation. The whole front-end is implemented in a 2P6M 0.18 mum RFCMOS process. It exhibits a voltage gain of 24dB and a SSB noise figure of 8.4 dB which make it suitable for most of the 2.5 GHz wireless short-range communication transceivers. The achieved power consumption is only 1.06 mW from a 1.2V power supply.

Electro-thermal characterization of a differential temperature sensor in a 65 nm CMOS IC: Applications to gain monitoring in RF amplifiers

This paper reports on the design solutions and the different measurements we have done in order to characterize the thermal coupling and the performance of differential temperature sensors embedded in an integrated circuit implemented in a 65 nm CMOS technology. The on-chip temperature increases have been generated using diode-connected MOS transistors behaving as heat sources. Temperature measurements performed with the embedded sensor are corroborated with an infra-red camera and a laser interferometer used as thermometer. A 2 GHz linear power amplifier (PA) is as well embedded in the same silicon die. In this paper we show that temperature measurements performed with the embedded temperature sensor can be used to monitor the PA DC behavior and RF activity.

On line monitoring of RF power amplifiers with embedded temperature sensors

In the present paper we analyze that DC temperature measurements of the silicon surface can be used to monitor the high frequency status and performances of class A RF Power Amplifiers. As a proof of concept, we present experimental results obtained with a 65 nm CMOS IC that contains a 2 GHz linear class A Power Amplifier and a very simple differential temperature sensor. Results show that the PA output power can be tracked from DC temperature measurements.