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Lecture Notes_23-26_MOSFET_2014

A time varying output signal is generated whose

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Unformatted text preview: This means that the PMOSFET is on and current flows from source to drain so that the output voltage Vo is equal to VDD (high). When the input VI is positive and large (high), it is above the threshold voltage of NMOSFET and NMOSFET conducts. This means that there is current flowing from source to drain of the NMOSFET, and Vo becomes near ground (low). On the other hand, the gate voltage VI relative to the source of the PMOSFET is small, near zero, which means the PMOSFET is off. Thus, we have an inverter: input high means output low and vice versa. The figure plots output voltage vs. input voltage. Regardless of the input being high or low, there is always one transistor in the off state, and, therefore, CMOS has very low leakage current from VDD to ground. Such low- power consumption is important for integrated circuits when there are hundreds of thousands or million transistors in a chip. This slide is taken from P. 227 of Neamen’s book, An Introduction to Semiconductor Devices. One application of a MOSFET is to amplify a small, time- varying input signal. If the input signal is vi = 0, then the transistor is to be biased in...
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