# questions in RF Circuit Design book

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#### baby_1 Hello dear

in the first page "The effect of component q on loaded q"
this paragraph shows me that the equivalent of the inductor with series resistor in parallel.
1-what the inductor in parallel shows us?(at resonant and after and befor)

in the next page(2)
how does it draw the equivalent of inductor resistor in scheme 2-16C from 2-16B?because we have only inductor q and capacity in Henry with out resonant frequency?

Thanks

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• RF Circuit Design.pdf
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#### FvM

##### Super Moderator
Staff member 1- The equivalent circuit is only valid for a single frequency
2- The resonance frequency is implicitely given by the parallel capacitor

• baby_1

### baby_1

Points: 2

#### baby_1 Thanks FVm such as always
1-the equvalent shows what?could tell me an example?
2-could you calculate the Resistor in question 2 because according the text its related to inductor not capacitor?:

#### FvM

##### Super Moderator
Staff member A RL series circuit with the impedance Z = R + jωL can be replaced by a parallel circuit with identical impedance
1/Z = Y = 1/R1 + 1/jωL1.

because according the text its related to inductor not capacitor
I didn't tell different. The capacitor allows to calculate the resonance frequency.

• baby_1

### baby_1

Points: 2

#### baby_1 Hello fvm
1-could you calculate with numeric equation according the uploaded file?i want to know how it find the 4.5Kohm resistor?
2-parallel equvalent of inductor with resistor shows us that in the resonant frequency we can omit the inductor and assume the parallel resistor only or shows us something else?

#### FvM

##### Super Moderator
Staff member 1-could you calculate with numeric equation according the uploaded file?i want to know how it find the 4.5Kohm resistor?
Unfortunately I can't because the numbers are apparently wrong. Rs=4.5k and Q=10 refers to XL=450 ohm. For the given L and C, XL in resonance is 45 ohm however. The numbers fit e.g. for L=5µ.

2- Yes. Omit L and C in resonance.

• baby_1

Points: 2