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# SPDT Dynamic (Single Pole Double Throw Switch, Dynamic)

## SPDT_Dynamic (Single Pole Double Throw Switch, Dynamic)

##### Parameters

Name

Description

Units

Default

Ron

On-state resistance of switch

Ohm

0

Roff

Off-state resistance of switch

GOhm

1

##### Range of Usage

Pin 1 is the input, pins 2 and 3 are output, pin 4 is the control voltage, Vc.
If Vc > 2V, R1 = Ron, R2 = Roff
If Vc < 1v, R1 = Roff, R2 = Ron
When Vc increases from 1V to 1.5V, R2 changes from Ron to Roff
When Vc increases from 1.5V to 2V, R2 = Roff and R1 changes from Roff to Ron
At Vc = 1.5V, R1 = R2 = Roff

##### Notes/Equations
1. This SPDT_Dynamic switch model, as opposed to the SPDT_Static model, can be used to dynamically switch states in response to the input control voltage. The input impedance of the control voltage port is infinite. Whenever the control voltage is greater than 2.0V, the input is connected to the (c>2) output with a resistance equal to Ron; otherwise, there is a resistance of Roff Ohm between the two pins. Similarly, whenever the control voltage is less than 1.0V, the input is connected to the (c<1) output with a resistance of Ron; otherwise, there is a resistance of Roff between the two pins. Note that when the control voltage is between 1.0V and 2.0V, the switch is open with respect to both outputs, simulating the break operation before making connection.
2. Capacitances, leakage currents, or other non-idealities are not included in this model.
3. This model is primarily meant for usage in the time domain (transient and circuit envelope) simulation with baseband control voltages. Due to the instantaneous, abrupt nature of the switching action, driving the control input with a carrier frequency input, in either harmonic balance or circuit envelope, should be avoided or done with careful consideration of the number of harmonics required and potential convergence problems.
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