Analog SET Analysis For Intergrated Circuits Of CMOS Amplifiers And Comparators

The space radiation environment is potentially harmful to microelectroniccircuits and systems which are used in the aerospace. In recent years，as thetechnology scale of the integrated circuits decreases，a new kind of single-eventeffects has been studied by the researchers in our country and abroad，that is thesingle-event transients(SET) in analog circuits. The researchers found that when ahigh energy article hit a circuit or a device，a set of movements will be appear in thatcircuit or device and this process is applicable to analog circuits。When a heavy ionpasses through the sensitive region of a transistor，the movable charge caused by theheavy ion will result in a voltage drift which finally will affect the output voltage ofthe circuits.The SET effect is studied in linear CMOS analog integrated circuits in thisthesis，mainly including single-transistor amplifier with resistive load, differentialamplifier and the comparator used in a successive approximation (SAR) ADC. Firstof all, the SET effect in analog integrated circuits is analyzed, then the TechnologyComputer-aided Design (TCAD) and circuit simulation softwares are used to carryout the SET sensitivity analysis of these analog integrated circuits. For the formertwo kinds of circuits, a mixed model simulation of circuit and device level is takenplace. While for the simulation of the comparator studied in this thesis, we used anindependent current source substitutes the transient current pulse generated by themixed model simulation to simulate the particle radiation effects. The circuitsstudied and the device model parameters used in the thesis are both based on SMIC0.18μm technology.In this article the effects in several commonly used analog circuits caused bySET are analyzed and the simulation results show that the transient current pulse isrelied on the input voltage of the CS amplifier and the energy of the incidenceparticle. With the increase of the input voltage the amplitude of the transient currentpulse decreases，while when the energy of the incidence particle is up to a certainrange the current pulse won’t suitable for the double exponential model, which laidthe foundation for later circuit level simulation. Then through analyzing thesensitive node of SET effect in the comparator we obtained that the most sensitivenodes are the drain of the input transistors. as the differential input voltageincreases,the output transient voltage pulse width decreases.