current starved inverter

[slchen]

As shown in the following figure, I use current starved inverter as the delay element in DLL design.
May I use the minimum length to deign M2 and M3?
I think they are just switches.
The charging and discharging currents are determined by M1 and M4.

Thanks alot

 

[jfyan]

differential inverter

As shown in the following figure, I use current starved inverter as the delay element in DLL design.
May I use the minimum length to deign M2 and M3?
I think they are just switches.
The charging and discharging currents are determined by M1 and M4.

Thanks alot

hi
i think it depends on some other specs,such as freq, matching, noise performance, and power.
for good noise, i think, the L of these two transistor is not suggested to use the minimum.
good luck
jeff

 

[cswang]

current starved oscillator

What's your operated frequency? The device size will introduce the paracitic cap, and will degrade yout speed.

 

[slchen]

transistor current starvation

What's your operated frequency? The device size will introduce the paracitic cap, and will degrade yout speed.

Thanks for Jeff and cswang.

The speed is 200MHz to 400MHz in 0.13um process.

Another question:

How to reduce the jitter due to supply/substrate noise, if using the current-starved inverter as delay element?

slchen

 

[lijianheng]

inverter psrr

For noise consideration, L may not to be minimum. To eject supply noise, refer to psrr, should enlarge the ac res from supply to output

 

[jfyan]

the current-starved inverter

What's your operated frequency? The device size will introduce the paracitic cap, and will degrade yout speed.

Thanks for Jeff and cswang.

The speed is 200MHz to 400MHz in 0.13um process.

Another question:

How to reduce the jitter due to supply/substrate noise, if using the current-starved inverter as delay element?

slchen

hi

i think, in your case, the current for such low frequency oscillator is small, so you can use buffer stage to drive your ring oscillator, that is, after the loop filter, you can use a unit gain buffer to drive the oscillator. in this case, the psrr is very good , i think.
good luck
jeff

 

[slchen]

use of current starved inverter over inverter

Thanks for jeff and lijianheng.

How about the differential current-starved inverter as shown in the attachment.
I think the PSRR can be improved (compared to the single-ended current starved inverter).

Another porblem:
Which inverter PSRR is better? differential current-starved inverter or symmetric-load differential inverter (Maneatis' type)?

slchen