<P> Some ICs combine analog and digital MOSFET circuitry on a single mixed - signal integrated circuit, making the needed board space even smaller . This creates a need to isolate the analog circuits from the digital circuits on a chip level, leading to the use of isolation rings and silicon on insulator (SOI). Since MOSFETs require more space to handle a given amount of power than a BJT, fabrication processes can incorporate BJTs and MOSFETs into a single device . Mixed - transistor devices are called bi-FETs (bipolar FETs) if they contain just one BJT - FET and BiCMOS (bipolar - CMOS) if they contain complementary BJT - FETs . Such devices have the advantages of both insulated gates and higher current density . </P> <Table> <Tr> <Td> </Td> <Td> This section does not cite any sources . Please help improve this section by adding citations to reliable sources . Unsourced material may be challenged and removed . (September 2016) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This section does not cite any sources . Please help improve this section by adding citations to reliable sources . Unsourced material may be challenged and removed . (September 2016) (Learn how and when to remove this template message) </Td> </Tr> <P> MOSFET analog switches use the MOSFET to pass analog signals when on, and as a high impedance when off . Signals flow in both directions across a MOSFET switch . In this application, the drain and source of a MOSFET exchange places depending on the relative voltages of the source / drain electrodes . The source is the more negative side for an N - MOS or the more positive side for a P - MOS . All of these switches are limited on what signals they can pass or stop by their gate - source, gate - drain and source--drain voltages; exceeding the voltage, current, or power limits will potentially damage the switch . </P>

What is the difference between cmos and mosfet