50 ohm buffer 10MHz to 40 MHz (wafer probe)

Status
Not open for further replies.
A

analog_chip

Full Member level 1
Joined
Oct 9, 2011
Messages
99
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,288
Activity points
1,994
Hi,
I want to design a 50 ohm buffer in frequency range 10MHz-40MHz which will be followed by wafer probes and then instruments. The baseband output of a receiver will be buffered.

I am planning for PMOS source follower with
a) current source load
b) resistive load

PMOS for low flicker noise. Which one is better a) or b).
Any other suggestion? I have no power limit. I need low noise.
 

Last edited:

If your requirement needs Low Noise, I suggest you to use Bipolar transistor at those frequencies if available.
Otherwise CMOS may be trouble..
 

Hi SunnySkyguy & BigBoss,

Thank you very much for your suggestions! I am using PMOS due to time constraints.
I have attached the circuit. i am using 3.3V I/O PMOS devices in 65nm process. The bias current is 5mA.

1. Is the current too high?

2. gm of M1 =1/Rload=1/50 (for S11=-15dB)

Gain=gm*Rload/(1+gm*Rload)=0.5
Is there a way to increase gain without matching circuit?

3. The sizes are
(w/l)1=600u/400n
(w/l)2,3,4,5=400u/400n
Is it ok to have different length devices in current source & M1? I am worried since thresholds may not track each other.

Is the design OK?

 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…