A sub-1-V, high precision, ultra low-power, process trimmable, resistorless voltage reference with low cost 90-nm standard CMOS technology Anass Samir • Edith Kussener • Wenceslas Rahajandraibe • Ludovic Girardeau • Yannick Bert • Herve ´ Barthe ´lemy Received: 19 September 2011 / Revised: 14 February 2012 / Accepted: 7 March 2012 / Published online: 1 April 2012 Ó Springer Science+Business Media, LLC 2012 Abstract A low power voltage reference generator operating with a supply voltage ranging from 1.6 to 3.6 V has been implemented in a 90-nm standard CMOS tech- nology. The reference is based on MOSFETs that are biased in the weak inversion region to consume nanowatts of power and uses no resistors. The maximum supply current at 3.6 V and at 125°C is 173 nA. It provides a 771 mV voltage reference. A temperature coefficient of 7.5 ppm/°C is achieved at best and 39.5 ppm/°C on aver- age, in a range from -40 to 125°C, as the combined effect of a suppression of the temperature dependence of mobility and the compensation of the threshold voltage temperature variation. Several process parameters affect the perfor- mance of the proposed voltage reference circuit, so a process adjustment aimed at correcting errors in the ref- erence voltage caused by these variations is dealt with. The total block area is 0.03 mm 2 . Keywords CMOS voltage reference  Ultra low-power  Weak inversion  Sub-threshold  Process variation  Process trimming management  Temperature compensation 1 Introduction The current trend towards low-power design is mainly driven by two reasons: the growing demand for long-life autonomous portable equipment and the technological limitations of high-performance systems. For the first cat- egory of products, low-power is the major goal for which speed and/or dynamic range might have to be sacrificed. High speed and high integration density are the objectives for the second application category, which has experienced a dramatic increase of heat dissipation that is now reaching a fundamental limit [1]. These two forces are now merging as portable equipment grows to encompass high-through- put computationally intensive products such as portable computers and cellular phones. The growing interest for such types of low-power appli- cations drives a dramatic demand for circuit building blocks operating with nanowatt power. Among them, voltage ref- erence generators are ubiquitous: they are used in almost all analog and digital systems to generate a DC voltage regardless of the supply voltage and temperature variations. Traditional Bandgap voltage references typically pro- vide a voltage around 1.2 V and therefore require a higher supply voltage (V DD [ 1.2 V). Moreover, if a low voltage reference is required to supply nanotechnologies (V DD \ 1.2 V), this constraint can be overcome by using resistive subdivision methods [2] that reduce the reference voltage but, increase current consumption. A. Samir (&)  L. Girardeau  Y. Bert STMicroelectronics, Z.I. Rousset-Peynier, B.P.2, 13106 Rousset Cedex, France e-mail: anass.samir@st.com L. Girardeau e-mail: ludovic.girardeau@st.com Y. Bert e-mail: yannick.bert@st.com E. Kussener  W. Rahajandraibe  H. Barthe ´lemy Microelectronics Department of the Institute of Materials, Microelectronics and Nanoscience of Provence University (IM2NP), UMR CNRS 6242, Marseille, Toulon, France e-mail: edith.kussener@isen.fr W. Rahajandraibe e-mail: wence@polytech.univ-mrs.fr H. Barthe ´lemy e-mail: herve.barthelemy@im2np.fr 123 Analog Integr Circ Sig Process (2012) 73:693–706 DOI 10.1007/s10470-012-9852-5