{{projectinfo|Tutorial| Time Domain Simulation of Generic RF Devices |RF198RFTUT12 20.png|In this project, you will build and test simple circuits that showcase the operation of several generic RF devices.|
*Generic RF Device
*Sinusoidal Waveform
*Pulse Waveform
*Scattering [[Parameters]]
*Wilkinson Power Divider
*Branchline Coupler
*Rat-Race Coupler
|All versions|{{download|http://www.emagtech.com/contentdownloads/project-file-download-repository|ProjectRepo/RFLesson12.zip RF Tutorial Lesson 12|[[RF.Spice A/D]] R15}} }}
=== What You Will Learn ===
In this tutorial you will explore the operation of several generic RF devices in [[RF.Spice A/D]] including Wilkinson Power Divider, Branchline Coupler and Rat-Race CouplersCoupler.
== Exploring the Wilkinson Power Divider==
</table>
Define a sinusoidal waveform for your voltage source according o to the table below:
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Run a Transient Test of this circuit with the [[parameters]] specified below:
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Run a Transient Test of your circuit with the [[parameters]] specified below:
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To see the effect of the pulse's rise and fall times, change the waveform one more time as specified below and run a transient test with the same [[parameters]] as above.
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Run a Transient Test of this circuit with the [[parameters]] specified below:
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|-
! scope="row"| Preset Graph Plots
| v(2), v(3), v(4), v(5)
|}
| Waveform TBD
|-
! scope="row"| X1X2
| Rat-Race Coupler
| Defaults, fc = 2G, len = 10
|}
[[File:RFTUT12 10.png|thumb|375px350px|Diagram of a Rat-Race Hybrid Coupler circuit.]]In this part of the tutorial lesson, you will examine [[RF.Spice]]'s Rat-Race Hybrid . This is primarily used as a 180° coupler as shown in the opposite figure. In this case, Port 3 is used as the input. The power is delivered to the output ports 1 and 4. Port 2 is the isolated port and is terminated in a 50Ω resistor. The output ports 1 and 4 have a 180<sup>o</sup> phase difference and are both terminated in equal 50Ω resistive loads. Place and connect the parts according to following simple circuit:
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<td>
[[File:RFTUT12 15.png|thumb|540px|The Rat-Race Hybrid Coupler circuitwith input port P3 and output ports P1 and P4.]]
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Run a Transient Test of this circuit with the [[parameters]] specified below:
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0 & 1 & -1 & 0 \end{array} \right] </math>
Before closing this section of the tutorial, let's swap the voltage source between Port 3 and Port 1 as shown in the figure below:
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[[File:RFTUT12 18.png|thumb|540px|The Rat-Race Hybrid Coupler circuit with input port P1 and output ports P2 and P3.]]
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In this case, Port 1 acts as the input port, Ports 3 and 2 are the output ports and Port 4 is isolated. Run a transient test with the same sinusoidal waveform and test parameters as before. The figure below shows the four port voltage graphs. Note that in this case the two output ports are in-phase. This is expected from the scattering matrix given above.
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<td>
[[File:RFTUT12 19.png|thumb|750px|The graph of the four port voltages of the Rat-Race Hybrid Coupler circuit.]]
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== Operating the Rat-Race Coupler in Σ-Δ Mode ==
The following is a list of parts needed for this part of the tutorial lesson:
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| valign="top"|
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{| class="wikitable"
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! scope="col"| Part Name
! scope="col"| Part Type
! scope="col"| Part Value
|-
! scope="row"| V1
| Voltage Source
| Waveform TBD
|-
! scope="row"| V2
| Voltage Source
| Waveform TBD
|-
! scope="row"| X1
| Rat-Race Coupler
| Defaults, fc = 2G, len = 10
|-
! scope="row"| R1 - R4
| Resistor
| 50
|}
One of the interesting functions of the rat-race hybrid coupler is when you feed two of its non-adjacent ports with two different signals. Then, the other two port produce the sum and difference of the two input signals. Place and connect the parts as shown in the figure below:
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<td>
[[File:RFTUT12 20.png|thumb|600px|The Rat-Race Hybrid Coupler circuit configured as a Σ-Δ coupler.]]
</td>
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Initially, use the same sinusoidal waveform for both of your voltage sources:
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| valign="top"|
|-
{| class="wikitable"
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! scope="row"| Offset Voltage
| 0
|-
! scope="row"| Peak Amplitude
| 1
|-
! scope="row"| Frequency
| 2G
|-
! scope="row"| Delay Time
| 0
|-
! scope="row"| Damping Factor
| 0
|}
Run a Transient Test of this circuit with the parameters specified below:
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| valign="top"|
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{| class="wikitable"
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! scope="row"| Start Time
| 0
|-
! scope="row"| Stop Time
| 5n
|-
! scope="row"| Linearize Step
| 1p
|-
! scope="row"| Step Ceiling
| 1p
|-
! scope="row"| Preset Graph Plots
| v(2), v(4), v(5), v(6)
|}
The four port voltage graphs are shown in the figure below. The input voltages v(2) and v(4) are 500mV due to the perfect input match. The output voltage v(6) is 707mV, while the other output voltage v(5) vanishes quickly. This is confirms that |v(6)| = |v(2) + v(4)|/√2 and |v(5)| = |v(2) - v(4)|/√2.
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<td>
[[File:RFTUT12 21.png|thumb|750px|The graph of the four port voltages of the Rat-Race Hybrid Coupler circuit configured as a Σ-Δ coupler.]]
</td>
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</table>
As another try, change the peak amplitude of the second voltage source V2 to 1.5V. Run a new Transient Test of the circuit with the same parameters and view the port voltage graphs as shown below. The following table shows the peak amplitudes of the four port voltage waveforms. The simulated results agree very well with the expected analytical results.
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| valign="top"|
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{| class="wikitable"
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! scope="col"| v(2)
! scope="col"| v(4)
! scope="col"| V(6)
! scope="col"| v(5)
! scope="col"| |v(2) + v(4)| /√2
! scope="col"| |v(2) - v(4)| /√2
|-
| 500mV
| 750mV
| 884mV
| 177mV
| 884.02mV
| 176.80mV
|}
<table>
<tr>
<td>
[[File:RFTUT12 22.png|thumb|750px|The graph of the four port voltages of the Rat-Race Hybrid Coupler circuit configured as a Σ-Δ coupler.]]
</td>
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