5
This chapter shows various ways of creating matching networks by sweeping values and using optimization.
Lab 5: Matching & Optimization
Lab 5: Matching and Optimization
5-2
OBJECTIVES
• Create an input match to the RF and an output match to the IF
• Tune and Optimize to achieve matching goals
Mixer Design Note: From the Smith Chart S-11 results in the last lab, it appears that a ries inductor can be added to the input as a first step in moving toward the center of the Smith chart for the RF match at 900 MHz. However, this does not take into consideration the other L and C components. But as a first step, it is reasonable to add the ries inductor and e the effects of tuning as ideal components are replaced with real values.
述职报告PROCEDURE
1. Create a new schematic design for the input match.
a. U the s_params design (last lab) and save it as: s_match .
b. Inrt an inductor L in ries to the input, as shown. Your circuit should look like the one here where the Sweep Plan and Z-ports are removed and t the S-parameter controller to sweep 15 MHz to 2.7 GHz – this will simulate most of the frequencies that will result when the LO is
added.
Lab 5: Matching and Optimization
学习画图
5-3
c. Check the sub-circuit to be sure there is no capacitor across the ba-collector (from the last lab).
d. Simulate and display S-11 in a new data display window. Position the dds window next to the schematic so you can e both at the same tim
e.The default datat should be the same name as the schematic:s_match . The results of the swept analysis should look like the plot here where a marker is added to show the value of S-11 at 900 MHz:
2. Start tuning the inductor
a. Select the inductor and start the tuning mode .
b. After the tuning dialog and status appear, open and position a new data display window near the tune control so you can e them both – move the schematic aside if necessary. Notice that the default datat name s_match will appear (same as the schematic).Inrt a Smith chart with S11 data and put a marker at 900 MHz. Notice that the S-11 trace is now changed with the real values of C and L.
c. Now, t the tune control to slider mode and move the slider back and forth between the ends. Notice that the value of S-11 changes very little
becau the range of inductance is too narrow.
Lab 5: Matching and Optimization
5-4d.Increa the tuning range: click the Details button and the more
detailed tune control appears. Increa the range from 0 to 30 by typing over the existing value. Bad on the imaginary part of the impedance (-j3.1), the conjugate value of inductance of 30 nH is clo enough. Also, t the resolution Step Size to step to something small such as 0.1 or
0.01 and increa Trace History to 20.
e.You should now be able to carefully move
the slider and click the step buttons until
you reach the impedance of j0.000 as
shown by the marker on the last trace.
You can u this technique for
determining the nsitivity of any
component.
f.Click the Update button on the tune狗上厕所
control and the value of L will appear on
危房鉴定申请
中国古代画家the component:
g.Save the data display as s_match
.
Lab 5: Matching and Optimization
孙策怎么死的
5-5
3. Build a new input matching network (new configuration)
CIRCUIT DESIGN NOTE: At this point, the addition of the ries inductor is only a first approximation. The remaining ideal components ( DC feeds and blocks) must be replaced by realistic values and this may require a completely different topology other than just adding a ries inductance. Also, a shunt capacitor needs to be added to the input to remove the IF signal that may
appear there. Therefore, instead of continuing to add components in an attempt to create a match, you will u the following configuration that will solve all the matching problems for the input. This will speed up the lab exerci.
a. On the input, remove the ries inductor you just tuned. It will be replaced by a network which will achieve the desired RF match and also provide the filtering.
b. Change the DC_Blocker to a real capacitor by highlighting the component name (e drawing - DC_Block) and typing in the new component name C and pressing Enter on the keyboard. The DC Block will automatically become a lumped capacitor:
c. Continue modifying the input topology: Inrt C=470 pF to shunt the IF (470 pF is a short to 45MHz). Also, change the DC_Feed1 to L=16 nH to allow the dc to flow but it will block (choke) the RF.Lastly, be sure the Z-ports have been removed .
d. Simulate the new input network with a new datat name: s_match_in
.
Enter. omponent by typing
方言的英语Lab 5: Matching and Optimization
5-6e.Plot the results and you should e a respon like the one shown here
where marker 1 is at the RF and marker 2 is the IF (almost an open).
However, the respon can be more finely tuned (next steps) so that the trace cross directly through the 50 ohm point.
f.Select the blocking capacitor and start
tune mode. Adjust the value of
capacitance until the trace cuts though the
center of the Smith chart. The next step will
be done to adjust the inductor so that 900
MHz is directly in the center.
g.Tune the inductor by adding it: click Details
. When the dialog
三国鼎立是哪三国
Tuning produces trace cutting
through desired impedance. Next
step: tune L to decrea input
inductance and maker should be at
desired point.
