A new CMOS voltage reference scheme based on Vth-difference principle

Abstract

a new CMOS voltage reference, which takes advantage of the temperature dependence of NMOS and PMOS threshold voltages, is presented. Due to the circuit architecture the mobility factor is completely cancelled. It does not use resistors and all transistors works in strong inversion. The circuit is simple, opamp-less and can be implemented in a standard CMOS process. When the input power supply changes from 1.8V to 2.1V and the temperature changes from -20 to 80ºC, simulations for the reference circuit using the proposed architecture shows an output voltage of 1.184V and a T FC of 100 ppm/ºC.

Temperature compensated low voltage MOSFET radiation sensor: proof of concept and a case study

“…The architecture is based on the threshold voltage difference principle without added parasitic transistors [18], [19], [20].…”

“…The operation of the circuit of Fig. 3 is explained from the analysis of two independent groups of transistors NMOS (T1 to T6) and PMOS (T7 and T8), as explained in detail in [18]. Each branch or group of transistors fulfills different functions, and therefore their designs must be approached independently.…”

“…3 was designed using the BSIM3 model for 1.5 AMm AMI technology. This model is chosen in particular in order to be able to contrast results with those obtained in [18] and [21]. It is worth noting that the directions of the VTH shifts on which the present proposal is based are independent of the integration technology used but depend on the type of incident radiation.…”

“…Long channel devices were chosen to minimize the effect of channel length modulation. From this basic concept, the design was made following equations (2) to (6) with the addition of the restrictions given in [18].…”

“…This work presents a simple and novel differential configuration to measure the radiation TID, which takes advantage of the difference between the threshold voltages of the NMOS and PMOS transistors (N and P channel MOSFETs respectively) for their operation [18], which which constitutes, as far as the authors are aware, an original and unpublished proposal. This arrangement allows the implementation of a radiation sensor with cancellation of thermal effects and power supply variation with rejection values comparable to that of a voltage reference generator, by using only 8 transistors and without the need for external processing, thus allowing its complete integration.…”