How to meaure switching speed of a SPDT switch

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Shoma Chandorkar

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can anyon tell me how How to meaure switching speed and Isolation of a SPDT switch which is th part of a subsystem(like Transmitter, receiver)?
 

Manufacturers of switch IC give usually test circuits in their data sheets, e. g. Annalog Devices. For RF switches, they are mainly based on matched impedance ports. Swiching speed would e. g. determined from the envelope of the output port signal with a RF generator at one input and a pulse generator at the control port. I don't see much room for unclearness in this regard.
 

If you want to meaure switching speed of a SPDT switch, you can use the R&S power sensor NRP-Z81 to capture the switching time. The smallest capture time can be 5ns.

R&S have one PC power sensor software , the power sensor can connect with USB. Very easy to use.

In the switching time measurement for SPDT, you can use function generator or signal generator which include pulse function and connect to the SPDT input. Power sensor connect to the SPDT output.


If you want to measure the RX/TX switching time in the related standard like GSM , WLAN ,Wimax,... .You must use the spectrum which include the related standard option.
 

Isolation is defined as the ratio of the power level when the switch’s path is
“off” to the power level when the switch is “on”.

In other words, it is the suppression of a signal in excess of the insertion loss at the “off” port.

Power sensor dynamic range is no enough , only 90dB (from +23dbm to -67dbm).

From isolation measurement , I suggest that use the spectrum measure the more lower signal to -140dbm.
 

You can buy for approx $100 a Crystal Detector that have a very fast output response (~200 pico-sec).
Adding a signal generator and a triggered scope you can measure very fast switching times.

**broken link removed**
 

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