Fast switching mechanism

Thread Starter

Atif hussain shah

Joined Sep 6, 2020
18
Screenshot_20210711-103200.pngI want to use a very fast Spdt Rf switch Masw20000 and want to control it through Fpga.it has two control signal inputs A and B. The control signals required for this switch are 0V and -5V for switching of one state and -5v and 0v for switching to other state.
The problem is that i cannot provide -5v from fpga.
One solution is to use an inverter but its responce is slow.
I want to genarate control signals 0v and -5v within 1ns.
If Any idea or solution
 

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crutschow

Joined Mar 14, 2008
28,204
Here's the LTspice simulation of a common-base PNP level shifter which may meet your needs.

Note that the transistor must be a device designed for fast saturated switching (no 2N3906 or similar general purpose transistors) and the input must be a high speed, fast rise-time driver circuit capable of driving an 80Ω load at 0-5V or a 42Ω load at 0-3V.


1625983794505.png
 

Thread Starter

Atif hussain shah

Joined Sep 6, 2020
18
Here's the LTspice simulation of a common-base PNP level shifter which may meet your needs.

Note that the transistor must be a device designed for fast saturated switching (no 2N3906 or similar general purpose transistors) and the input must be a high speed, fast rise-time driver circuit capable of driving an 80Ω load at 0-5V or a 42Ω load at 0-3V.


View attachment 243158
Thanks for reply
Most BJTs like above you have used(2N5771) has on and off time around 10 to 15 ns. I think this time will effect the switching speed
 

Papabravo

Joined Feb 24, 2006
17,296
Thanks for reply
Most BJTs like above you have used(2N5771) has on and off time around 10 to 15 ns. I think this time will effect the switching speed
You are falling victim to misleading datasheet parameters. Look at the currents involved for the datasheet value. Then look at the currents in the simulation. It is a world of difference.
 
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