MOSFET digital circuit
　Digital technology advances, such as the continuous improvement of microprocessor performance, to further develop a new generation of MOSFET MOSFET more power, which also makes the operation of the MOSFET itself faster and faster, almost as a variety of semiconductor active components in the fastest One kind. MOSFET in the digital signal processing on the most important success from the invention of CMOS logic circuit, the biggest advantage of this structure is theoretically there will be no static power loss, only in the logic gate (logic gate) switching action when the current through The CMOS logic gate is the most basic members of the CMOS inverter (inverter), and all the basic operation of the CMOS logic gate as the inverter, the logic of the moment in the same time there must be only one transistor (NMOS or PMOS) In the open state, the other must be cut-off state, which makes the power from the terminal to the ground will not have a direct conduction path, a large number of savings in current or power consumption, but also reduces the heat of the integrated circuit.
　Another advantage of MOSFETs in digital circuits is that the gate-side impedance of the MOSFET is infinite (equivalent to open) for DC (DC) signals, that is, theoretically no current flows from the gate of the MOSFET Circuit in the ground, but completely controlled by the voltage in the form of the gate. This makes the MOSFET and their main competitor BJT compared to more power, but also easier to drive. In the CMOS logic circuit, in addition to the driver responsible for driving off-chip load (off-chip load) driver (driver), each level of the logic gate as long as the face of the same MOSFET gate, so do not consider the logic The driving force of the door itself. In contrast, BJT's logic (such as the most common TTL) does not have these advantages. The gate's input resistance of the MOSFET is extremely limited. For circuit designers, there are other advantages, such as the loading effect of the logic gate output.

　Analog circuit
　For a while, MOSFETs are not the first choice for analog circuit design engineers because the analog circuit design focuses on performance parameters such as transistor transconductance or current driving force, and MOSFETs are better suited for analog circuits than BJT. But with the continuous evolution of MOSFET technology, today's CMOS technology has also been able to meet a lot of analog circuit specifications. Coupled with the MOSFET because of the structure of the relationship, there is no BJT some fatal shortcomings, such as thermal damage (thermal runaway). In addition, MOSFET in the linear region of the voltage-controlled resistance characteristics can also be used in the integrated circuit to replace the traditional polysilicon resistance (poly resistor), or MOS capacitor itself can be used to replace the commonly used polysilicon - insulator - polysilicon capacitor (PIP capacitor) , Even in the appropriate circuit control can show the characteristics of the inductor, these benefits are difficult to provide BJT. In other words, the MOSFET in addition to play the role of the original transistor, but also can be used as a large number of analog circuits used passive devices (passive device). This advantage allows the use of MOSFET to achieve analog circuits can not only meet the specifications of the demand, but also can effectively reduce the chip area, reduce production costs.
　With the progress of semiconductor manufacturing technology, for the integration of more features to a single chip also followed a substantial increase in demand, this time with MOSFET design analog circuit, another advantage also emerge. In order to reduce the number of integrated circuits used on printed circuit boards (PCBs), reduce package costs and reduce the size of the system, many of the original independent analog chips and digital chips are integrated into the same chip. MOSFET in the digital IC has a great competitive advantage in the analog IC is also a large number of integrated circuits, the two different functions of the circuit integration difficulties also significantly decreased. Also like some mixed-signal circuits, such as analog-to-digital converters (ADCs), MOSFETs can be used to design better-performing products.