T-network calculator

T-network matching network calculator
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Updated Thu, 21 May 2020 15:11:53 +0000

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This code returns the t-network matching network's elements' values:
--> Xs_1: 1st series reactance
--> Xs_2: 2nd series reactance
--> Xp: the parallel reactance
--> C_s//L_s: 1st series capacitor (F) or inductance (H)
--> C_p//L_p: parallel capacitor (F) or inductance (H)
--> C_s//L_s 2nd series capacitor (F) or inductance (H)
--> IL_dB: the network's insertion loss (dB)

For getting the above values, it requires the following inputs:
--> fc: center frequency of the wanted resonant circuit (Hz)
--> B: bandwidth of the wanted resonant circuit (Hz)
--> Rs: source resistance
--> RL: load resistance
--> flag: any value, just for number of input purposes
OR
--> fc: center frequency of the wanted resonant circuit (Hz)
--> Rs: source resistance
--> RL: load resistance
--> Q: T-networks quality factor

It allows to choose among the 4 T-network topologies:

(1) Series inductor, parallel capacitance, series inductor
(2) Series capacitance, parallel inductance, series capacitance
(3) Series inductance, parallel capacitance, series capacitance
(4) Series capacitance, parallel inductor, series inductor

The decision among the 4 models is asked after executing the function.

---------------------------------------------------------------------------------
Here is an example of a FM band mixer's T-network, with topology == 1:
---------------------------------------------------------------------------------

>> fc = 98e6; % Hz
>> Rs = 50: % Ω
>> RL = 1.5e3; % Ω
>> Q = 10;

>> [Xs_1,Xs_2,Xp,L_1,C,L_2,IL_dB] = t_network(fc,Rs,Rl,Q);

|********************** T-NETWORK ****************************
|
|Initial data
| Center frequency (fc): 98.00 MHz
| Serial resistance (Rs): 50.00 Ω
| Load resistance (Rl): 1.50 kΩ
| T-network's Quality factor (Q): 10.00
|
|********************** MATCHING NETWORK ****************************
|
| Knowing that:
|
| Q_i = sqrt√(Rp_i/Rs_i) (1)
| Q_i = Xs_i/Rs_i = Rp_i/Xp_i (2)
| and,
|
|
| Rs_1: 50.00 Ω
| Rp_1: 5050.00 Ω
|
|
| Rs_2: 1500.00 Ω
| Rp_2: 5050.00 Ω
|
| then,
|
| Xs_1: 500.00 Ω
| Xp_1: 505.00 Ω
|
|
| Xs_2: 2307.60 Ω
| Xp_2: 3282.64 Ω
|
|
|
| Choose your T-network configuration:
|
| (1) Series inductor, parallel capacitance, series inductor
| (2) Series capacitance, parallel inductance, series capacitance
| (3) Series inductance, parallel capacitance, series capacitance
| (4) Series capacitance, parallel inductor, series inductor
|
Your decision:
>>1

| Your decision: 1
|
| Obtained reactances,
|
|
| Xs_1 = 500.000000 Ω
|
|
| Xp = 437.669098 Ω
|
|
| Xs_2 = 2.307596 kΩ
|
| and the values for the T-network's inductances and capacitances,
|
|
| ----------------------------------
| |
| | Series, L_1 = 812.015016 nH |
| | |
| | Parallel, C = 3.710634 pF |
| | |
| | Series, L_2 = 3.747605 uH |
| |
| ----------------------------------
|
| Finally, we calculate the insertion loss of the network,
|
| IL = 20log10(VL/VL_in)
|
| IL = 20log10(RL/(RL + RS + Xs_1 + Xs_2))
|
|
| -------------------
| | IL(dB) : -9.26 |
| -------------------
*********************************************************************

Cite As

Gorka Zubia Garea (2024). T-network calculator (https://www.mathworks.com/matlabcentral/fileexchange/75561-t-network-calculator), MATLAB Central File Exchange. Retrieved .

MATLAB Release Compatibility
Created with R2020a
Compatible with any release
Platform Compatibility
Windows macOS Linux

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Version Published Release Notes
1.0.3

Function icon image change

1.0.2

".txt" archives' more intuitive name

1.0.1

minor improvements

1.0.0