MOSFET Technologies for Double-Pole Four-Throw Radio-Frequency Switch by Viranjay M. Srivastava & Ghanshyam Singh

Author:Viranjay M. Srivastava & Ghanshyam Singh
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

a.The oxide thickness is relatively thin.

b.The front and back oxides have equivalent thickness.

c.The ultrathin Si-film maximizes the coupling effects.

The transconductance decreases more rapidly with gate voltage in DG MOSFET, which indicates a larger value of the mobility degradation factor. Also, the transconductance gain of SG and DG at 300 °K tends to decrease in shorter channels. The gain of SG and DG in transconductance peaks (i.e., field-effect mobility) increases at the lower temperature as acoustic phonon scattering is gradually attenuated.

In Fig. 2.​7, four transistors are used for two antennas. In this transceiver system using the CMOS functionality, at a time, any one of transistor M1 (n-MOSFET) or M3 (p-MOSFET) will operate, and in the same fashion, any one of transistor M2 (n-MOSFET) or M4 (p-MOSFET) will operate. However, the same working functions have been observed in this DP4T DG RF CMOS switch as in Fig. 4.3 [11]. Since the drain current consumption is significantly reduced, so the CMOS-based RF switches allow longer battery life than PIN diodes and about 60 % smaller as compared to smallest GaAs RF switch. Furthermore, this switch also experiences minimal distortion, negligible voltage fluctuation, and low power supply of only 1.2 V as shown in the following sections.

This designed switch is a part of the microwave applications for the switching system between transmitting and receiving modes. In this work, the designed DP4T switch has a symmetrical structure of transmitter (Tx) and receiver (Rx) to be operated at GHz range. The transistors M1 and M2 perform the main ON and OFF switching function, while the shunt transistors M3 and M4 which are cascade to M1 and M2, respectively, are used to improve the isolation of the switch by grounding RF signals on the side which is turned OFF. The switch can also connect coupling capacitors C 1 and C 2 which allow DC biasing of the Tx and Rx nodes of the switch. The gate resistances R 1 and R 2 are implemented to improve DC isolation. After designing of DP4T DG RF switch with designed DG MOSFET at 45-nm technology, we have drawn the layout and simulated the electrical parameters of this switch. It includes the basics of the circuit elements parameter required for the radio-frequency subsystems of the integrated circuits such as drain current, threshold voltage, resonant frequency, return loss, transmission loss, VSWR, resistances, capacitances, and switching speed.

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