Why the Q of the inductor in the TSMC .18u technology is so small?

[benever]

Can someone why the Q of the inductor in the technics of TSMC .18u is so small


?





thanks!

 

[khouly]

Re: design the LC VCO

the integrated inductor usually have very low Q from 3 to 7 , max is 10

what is the Q factor did u got ?

most of the RFIC designs don't depend on the inductors supplied with the kit
they develop , and optimize they own L's to fit in the design

khouly

 

[benever]

Re: design the LC VCO

the Q now is about 4, the value of the inductor is about 4.5uH, but the parasitic

resistance is about 2 ohm, so the tank's resistance is about 40ohm, seemed it is too small.

am i right?

the integrated inductor usually have very low Q from 3 to 7 , max is 10

what is the Q factor did u got ?

most of the RFIC designs don't depend on the inductors supplied with the kit
they develop , and optimize they own L's to fit in the design

khouly

Added after 4 minutes:

the Q now is about 4, the value of the inductor is about 4.5uH, but the parasitic

resistance is about 2 ohm, so the tank's resistance is about 40ohm, seemed it is too small.

am i right?

the integrated inductor usually have very low Q from 3 to 7 , max is 10

what is the Q factor did u got ?

most of the RFIC designs don't depend on the inductors supplied with the kit
they develop , and optimize they own L's to fit in the design

khouly

 

[khouly]

Re: design the LC VCO

it is the range of integrated inductors , but with some custmization in layout u can achive better results , specailly in Q

Khouly

 

[pfd001]

Re: design the LC VCO

It seems that you use a large inductor. Q=4 is reasonalbe.

the Q now is about 4, the value of the inductor is about 4.5uH, but the parasitic

resistance is about 2 ohm, so the tank's resistance is about 40ohm, seemed it is too small.

am i right?

the integrated inductor usually have very low Q from 3 to 7 , max is 10

what is the Q factor did u got ?

most of the RFIC designs don't depend on the inductors supplied with the kit
they develop , and optimize they own L's to fit in the design

khouly

Added after 4 minutes:

the Q now is about 4, the value of the inductor is about 4.5uH, but the parasitic

resistance is about 2 ohm, so the tank's resistance is about 40ohm, seemed it is too small.

am i right?

the integrated inductor usually have very low Q from 3 to 7 , max is 10

what is the Q factor did u got ?

most of the RFIC designs don't depend on the inductors supplied with the kit
they develop , and optimize they own L's to fit in the design

khouly

 

[benever]

Re: design the LC VCO

another question, after adjust the W/L of the MOSFET, i see that the (Cgd+Cgs+Cdb)n,p is very large, for example, the total C i want is about 1.2pF,but the total parasitic Cap of the MOSFET is about 0.8pF, tell me it is reasonable? ( becuse i shoulld make the tail MOSFET saturate)


waiting for your reply!


thanks

it is the range of integrated inductors , but with some custmization in layout u can achive better results , specailly in Q

Khouly

 

[khouly]

Re: design the LC VCO

usually the tail MOS is large to make the Vdsat is low

about the paracitics do u mean the cross coupled pair of the tail MOS

khouly

 

[benever]

Re: design the LC VCO

yeah.you are right! just the croosed!

i don't whether it is reasonable.

usually the tail MOS is large to make the Vdsat is low

about the paracitics do u mean the cross coupled pair of the tail MOS

khouly

Added after 2 minutes:



yeah.you are right! just the croosed!

i don't whether it is reasonable.

usually the tail MOS is large to make the Vdsat is low

about the paracitics do u mean the cross coupled pair of the tail MOS

khouly

 

[khouly]

Re: design the LC VCO

what is the W and L of ur cross coupled Pair , and what is ur oscillation frequency ?

khouly

 

[benever]

Re: design the LC VCO

PMOS is 8*20/0.4

NMOS IS 2.5*20/0.4

Frequency is 2G





quote="khouly"]what is the W and L of ur cross coupled Pair , and what is ur oscillation frequency ?

khouly[/quote]

Added after 1 hours 31 minutes:



another question, my phase noise is higher than i want


i see some articles say that at the tail current MOS to improve the characteristic of Pnoise , i don't konw how ?

need your help!

thanks

what is the W and L of ur cross coupled Pair , and what is ur oscillation frequency ?

khouly

 

[eeliuliu]

design the LC VCO

in my mind,about the process of TSMC 0.18um RF technology, Q value of inductor is near to 10.

 

[khouly]

Re: design the LC VCO

try to use the MOS minimum length which is 0.18 U not .4 , this will minimize the parasitics

khouly

 

[benever]

Re: design the LC VCO

I've tried ,but still the pnoise is not as lower as i want ,
any other good ideas?

thanks !


quote="khouly"]try to use the MOS minimum length which is 0.18 U not .4 , this will minimize the parasitics

khouly[/quote]

 

[khouly]

Re: design the LC VCO

u need to minimize the pnoise u should increase the quality factor of ur resonator . and try to check whcih part of ur oscillator is the source of the noise

khouly

 

[benever]

Re: design the LC VCO

sorry to disturb you again,
now the output Voltage rang is form the power supply(a litter high) to a minus , i don't konw why . obviously , at
the monment ,the tail current (MOSFET) can't work. in my opinion , the Voltage rang should be high but lower than the power supply ,and low but high enough to make sure the tail current work.

but now ,the simulating result is not as i thought,

why ? waiting for your reply!

thanks.

quote="khouly"]u need to minimize the pnoise u should increase the quality factor of ur resonator . and try to check whcih part of ur oscillator is the source of the noise

khouly[/quote]

 

[khouly]

Re: design the LC VCO

can u send ur schamtic , including w/l ratios and i will check them
which tool do u use in simulation cadence or ads

khouly

 

[mitgrace]

Re: design the LC VCO

I think if you want to design LC VCO , teh inductor , You can use ads moment to check the Q. Then you have good ideal for this design