Limits...
A Low-Cost CMOS Programmable Temperature Switch

View Article: PubMed Central

ABSTRACT

A novel uncalibrated CMOS programmable temperature switch with high temperature accuracy is presented. Its threshold temperature Tth can be programmed by adjusting the ratios of width and length of the transistors. The operating principles of the temperature switch circuit is theoretically explained. A floating gate neural MOS circuit is designed to compensate automatically the threshold temperature Tth variation that results form the process tolerance. The switch circuit is implemented in a standard 0.35 μm CMOS process. The temperature switch can be programmed to perform the switch operation at 16 different threshold temperature Tths from 45—120°C with a 5°C increment. The measurement shows a good consistency in the threshold temperatures. The chip core area is 0.04 mm2 and power consumption is 3.1 μA at 3.3V power supply. The advantages of the temperature switch are low power consumption, the programmable threshold temperature and the controllable hysteresis.

No MeSH data available.


Related in: MedlinePlus

The dependence of Vb on temperature T with three different threshold voltages. It's calculated based on Eq. (6). ξ=1.65, γ=0.7V1/2, KT=1.1mV/K, K43=2, K31=1.4 and K35=560.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3675537&req=5

f3-sensors-08-03150: The dependence of Vb on temperature T with three different threshold voltages. It's calculated based on Eq. (6). ξ=1.65, γ=0.7V1/2, KT=1.1mV/K, K43=2, K31=1.4 and K35=560.

Mentions: In Eq. (4) the derivative of Tth w.r.t VTH0 is larger than zero, so Tth increases linearly with VTH0 and the slope is very sharp. Figure 3 shows the calculated dependence of Vb on temperature T with three different threshold voltages. It indicates that the threshold temperature Tth depends strongly on the threshold voltage of MOS transistor. A VTH0 variation of 50mV results in a Tth change of 20 K. In these calculations we used the following conditions: ξ=1.65, K43=2, γ=0.7 V1/2, KT =1.1mv/K. The curves show that there are two solutions for a certain temperature only if the temperature is lower than a critical temperature. The solution with a larger Vb corresponds to the stable operating state of the switch circuit. The transistor N1, N2, N3 and N4 operate in the subthreshold region. The solution with a small smaller Vb is a pure mathematic one and does not correspond to the physical state of the switch circuit. It is not taken into account in the study. When the temperature increases to and exceeds the critical temperature, the operation of the circuit changes suddenly and all of the transistors N1, N2, N3, N4, N5, P1 and P2 cut off so that no solution can be obtained by the above equations and Vb becomes almost zero. The critical temperature is considered as the threshold temperature Tth. The N1, N2, N3 and N4 transistors in the switch are all in the subthreshold region, so the currents through them are quite small and power consumption is very low.


A Low-Cost CMOS Programmable Temperature Switch
The dependence of Vb on temperature T with three different threshold voltages. It's calculated based on Eq. (6). ξ=1.65, γ=0.7V1/2, KT=1.1mV/K, K43=2, K31=1.4 and K35=560.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3675537&req=5

f3-sensors-08-03150: The dependence of Vb on temperature T with three different threshold voltages. It's calculated based on Eq. (6). ξ=1.65, γ=0.7V1/2, KT=1.1mV/K, K43=2, K31=1.4 and K35=560.
Mentions: In Eq. (4) the derivative of Tth w.r.t VTH0 is larger than zero, so Tth increases linearly with VTH0 and the slope is very sharp. Figure 3 shows the calculated dependence of Vb on temperature T with three different threshold voltages. It indicates that the threshold temperature Tth depends strongly on the threshold voltage of MOS transistor. A VTH0 variation of 50mV results in a Tth change of 20 K. In these calculations we used the following conditions: ξ=1.65, K43=2, γ=0.7 V1/2, KT =1.1mv/K. The curves show that there are two solutions for a certain temperature only if the temperature is lower than a critical temperature. The solution with a larger Vb corresponds to the stable operating state of the switch circuit. The transistor N1, N2, N3 and N4 operate in the subthreshold region. The solution with a small smaller Vb is a pure mathematic one and does not correspond to the physical state of the switch circuit. It is not taken into account in the study. When the temperature increases to and exceeds the critical temperature, the operation of the circuit changes suddenly and all of the transistors N1, N2, N3, N4, N5, P1 and P2 cut off so that no solution can be obtained by the above equations and Vb becomes almost zero. The critical temperature is considered as the threshold temperature Tth. The N1, N2, N3 and N4 transistors in the switch are all in the subthreshold region, so the currents through them are quite small and power consumption is very low.

View Article: PubMed Central

ABSTRACT

A novel uncalibrated CMOS programmable temperature switch with high temperature accuracy is presented. Its threshold temperature Tth can be programmed by adjusting the ratios of width and length of the transistors. The operating principles of the temperature switch circuit is theoretically explained. A floating gate neural MOS circuit is designed to compensate automatically the threshold temperature Tth variation that results form the process tolerance. The switch circuit is implemented in a standard 0.35 μm CMOS process. The temperature switch can be programmed to perform the switch operation at 16 different threshold temperature Tths from 45—120°C with a 5°C increment. The measurement shows a good consistency in the threshold temperatures. The chip core area is 0.04 mm2 and power consumption is 3.1 μA at 3.3V power supply. The advantages of the temperature switch are low power consumption, the programmable threshold temperature and the controllable hysteresis.

No MeSH data available.


Related in: MedlinePlus