Nonvolatile Analog Switch for Low-Voltage Applications

In this paper, a nonvolatile switch based on n-type floating-gate transistors is described. The switch states are programmed through the memory cell floating-gate voltage, allowing higher levels than the application supply. Furthermore, due to its nonvolatile nature, the power consumption is reduced. The on-state resistance, which does not depend on the supply voltage, is one of the greatest advantages of this type of switch in comparison to conventional switches. This benefit can be successfully exploited in low-voltage applications. The switch on-resistance can be increased without the need for increasing the switch area. The characteristics of the proposed switch were confirmed by the experimental results obtained on a test chip fabricated in a 0.18 µm EEPROM process. Measured on-resistance values between 45 and 70 Ω were obtained for a floating-gate voltage of 6.2 V and input source levels below 2 V. The required programming voltage was 18 V. The maximum off-state leakage current was measured at 5 nA.