MOSFET

How are the transistors connected in a CMOS two-input NAND gate?

  1. ATwo pMOS in series and two nMOS in parallel
  2. BTwo pMOS in parallel and two nMOS in series
  3. CAll four in parallel
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Answer: B. Two pMOS in parallel and two nMOS in series

A NAND outputs 0 only when both inputs are 1, so nMOS transistors are placed in series between the output and ground so the output connects to 0 only when both are on. pMOS transistors are placed in parallel between the output and supply so the output connects to 1 if either input is 0. A NOR uses the opposite connection.

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More MOSFET questions

  1. Which phenomenon increases off-state leakage because band-to-band tunneling current flows due to the strong field where the gate overlaps the drain?
  2. What circuit advantage results from almost no current flowing into the gate of a MOSFET?
  3. Which is a characteristic of a MOSFET source follower (common-drain) circuit?
  4. How does the absolute value of a MOSFET's threshold voltage generally change as temperature rises?
  5. How should the dimensions be changed to increase a MOSFET's drain current?