Use of multiple switches at high frequency

Thread Starter

ranaiftikhar

Joined Nov 1, 2016
42
Why shunt (or multiple switches) switches (like MOSFET etc) are preferred instead of single switch at high frequencies (like mm wave range)?

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GopherT

Joined Nov 23, 2012
8,012
Why shunt (or multiple switches) switches (like MOSFET etc) are preferred instead of single switch at high frequencies (like mm wave range)?

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Do you have an example? You may be looking at a "cascode" , a pair of transistor's in a specific arrangement that reduces (compemsates for) capacitance and, therefore, works better in a high frequency circuit. Look for the Miller Effect and Cascode. Now, that is all a guess based on what you are asking with few words and no schematics.
 
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Thread Starter

ranaiftikhar

Joined Nov 1, 2016
42
Dear GopherT
Thanks for your kind look. In figure (a) data is required to be transmitted from port 1 to port 2. In order to block signal, MOSFET is turned on to provide a path to ground for signal from PORT 1. This was possible with 1 switch only but what is the benefit of using multiple switches in this case as shown in (b).

Thanks
upload_2016-12-12_14-19-11.png

Ref : M. Uzunkol and G. M. Rebeiz, "140–220 GHz SPST and SPDT Switches in 45 nm CMOS SOI," in IEEE Microwave and Wireless Components Letters, vol. 22, no. 8, pp. 412-414, Aug. 2012.
 

GopherT

Joined Nov 23, 2012
8,012
Dear GopherT
Thanks for your kind look. In figure (a) data is required to be transmitted from port 1 to port 2. In order to block signal, MOSFET is turned on to provide a path to ground for signal from PORT 1. This was possible with 1 switch only but what is the benefit of using multiple switches in this case as shown in (b).

Thanks
View attachment 116746

Ref : M. Uzunkol and G. M. Rebeiz, "140–220 GHz SPST and SPDT Switches in 45 nm CMOS SOI," in IEEE Microwave and Wireless Components Letters, vol. 22, no. 8, pp. 412-414, Aug. 2012.

The SPST means single throw, single throw which means a standard simple switch (let me know what the other text on this textbook page says SS and DS mean).

The difference between a and b are in those definitions of SS and DS.
 
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