Advantages of Dual Gate MOSFET | Disadvantages of Dual Gate MOSFET

This page covers advantages and disadvantages of Dual Gate MOSFET and its basics. It mentions benefits or advantages of Dual Gate MOSFET and Challenges or disadvantages of Dual Gate MOSFET.

What is Dual Gate MOSFET?

It is one form of MOSFET which is popular for various RF applications. It consists of two control gates in series as shown in the figure. These gates are constructed along the length of channel one after the other. These gates influence level of current flowing between S (Source) and D (Drain) terminals.

Dual Gate MOSFET

It functions similar to two MOSFET devices connected in series. These gates affect normal operation of MOSFET and consecutively gives output. Dual gate MOSFET is used in different applications which include RF mixers, RF multipliers, RF amplifiers, Amplifiers with gain control etc. The Dual Gate devices are popular to use in circuit designs in sub-50 nm technology. The figure depicts construction of dual gate MOSFET and symbols of n-channel and p-channel dual gate MOSFET devices.

The second gate is operated at fixed voltage to keep feedback capacitance between drain and gate smaller. The voltage applied on gate terminals controls electric fields. This determines amount of current flow through the channel.

Features of Dual Gate MOSFET are as follows.
• Upper and lower gates control the channel region.
• Ultra thin body acts as rectangular quantum well at device limits.
• Directly scalable down to 20nm channel length.

Applications :
• To construct low power logic gates
• Single transistor mixer
• Demodulators, cascade amplifiers, RF amplifier, AGC amplifier.

Different layouts are used in dual gate designs which include planar double gate, vertical double gate and horizontal double gate.

Benefits or advantages of Dual Gate MOSFET

Following are the benefits or advantages of Dual Gate MOSFET:
➨The two gates of this MOSFET type helps to control unwanted capacitive effects at higher frequencies.
➨It offers better control of channel from the gates. It provides better electrostatic control over the channel.
➨It reduces short channel effects. Hence it offers better scalability and lower sub threshold current.
➨It offers better ION/IOFF.
➨It offers improved sub-threshold slop (about 60mV/decade).
➨There is no discrete dopant fluctuations.
➨It has lower gate leakage.

Challenges or disadvantages of Dual Gate MOSFET

Following are the challenges of Dual Gate MOSFET technology :
➨Identically sized gates are needed.
➨Self alignment of source and drain to both gates.
➨Alignment of both gates to each other.
➨Connecting two gates with low resistance path.

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