Ageing and embedded instrument monitoring of analogue/mixed-signal IPS

With an increasing number of SoCs being used in safety-critical applications like automotive, highly dependable circuits become an important research topic. However, most of the effort until now was spend on pure digital blocks. The most critical part, the analogue front-ends are hardly being dealt with. Therefore, the focus of this thesis is on dependable Analogue/mixed-signal Front-Ends in safety-critical applications like automotive. In this thesis, an overview of the dependability of CMOS AMS circuits is provided. Emphasis is put on the reliability phenomena of nano-meter CMOS transistors (65nm and below), especially on the dominating NBTI reliability effects. Since this thesis is dominated by NBTI simulations, NBTI physical mechanisms, modelling and simulations are treated in detail. The target AFE in the thesis is also introduced. Two main directions to improve dependability are discussed. Two original works are described, dealing with models. One original contribution is a NBTI compact model, which is later used to simulate NBTI degradation of analogue/mixed-signal circuits. Another original result is the MOS drain-current model which is used to build an on-chip Vth0 measurement Embedded Instrument and gather a large amount of NBTI degradation data which is more convenient to design as well as featuring low costs. After setting up the reliability model and simulation method, different analogue IP blocks are simulated and discussed to make the analogue IPs dependable. An offset and gain Embedded Instrument for OpAmp IPs is subsequently designed based on a new measurement theory. Several active filters and a 10-bits fully differential SAR ADC are designed in 65nm CMOS technology. Three extra embedded instruments are introduced to detect bandwidth error in OTA-C filters and timing as well as offset errors in the SAR ADCs. Based on the information above, some general conclusions are drawn. Limitations of the current and future research are also addressed. At the end of the thesis, all publications written by the author are listed.