# How is the transfer function of the feedback system obtained

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#### STOIKOV

##### Full Member level 4
Oscillator theory

I started reading about VCOs,

How is the transfer function of this feedback system obtained ?
Recommend some literature about CMOS ring oscillators ?

thanks.

#### jprmlmdlc

##### Newbie level 1
Re: Oscillator theory

Have a look to these:
**broken link removed**

and 2 this gr8 tutorial:
**broken link removed**

They could be interesting for you.

C u.

### STOIKOV

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#### v_c

##### Advanced Member level 2
Re: Oscillator theory

I just answered your other post ... so take a look here

For CMOS ring oscillators please take a look at this document

**broken link removed**

I hope you find the information useful.

Best regards,
v_c

### STOIKOV

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#### eda_freak

##### Member level 3
Re: Oscillator theory

input to amplifier at any time is vin(actual)=vin-vout
therefore
vout=H(s)*v(actual)
or vout=H(s)[vin-vout]
vout+vout*H(s)=vin*H(s)
vout[1+H(s)]=vin*H(s)
therefore, vout/vin = H(s)/{1+H(s)}
which is the said transfer function...
you can read this theory in Behzad Razavi's analog CMOS design book.

### STOIKOV

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