need help in design bias circuits for LNA

[wizardyhnr]

i am designing a LNA, now i need a bias circuit to provide the MOSFET a precise
voltage. i have find several circuits, but the precision of the voltage highly depend on
the precision of resistor. Since i use the TSMC0.18 process, the precision of resistor in
CMOS process is not so satisfying. anyone who can provide me a bias circuit suitable
for CMOS process

 

[chunlee]

I don't sure what you mean with precision of resistor in CMOS process is not so satisfying. But if you mean for temperature dependence of the resistor, the proper voltage divider circuit design and layout can solve the problem.

 

[liujs_825]

I design a LNA too, but the bias circuit is simple. I think we can get precise value of the resistor after careful layout.

 

[wizardyhnr]

my solution use two resistors to divide the voltage
the resistor ratio determines the bias voltage of the LNA, so the ratio must to be
precise, otherwise the bias current would change.

 

[cmosbjt]

my solution use two resistors to divide the voltage
the resistor ratio determines the bias voltage of the LNA, so the ratio must to be
precise, otherwise the bias current would change.

I don't think this is a good solution. In simulation, you can find out what bias voltage will give a disired main current, but this REQIRED bias voltage varies quite a lot due to the process, temperature variation. A precise bias voltage can not guarantee a desired main current, that's why we need current mirror.

 

[springf2000]

use the active bias circuit to arrive your aim, or use a operation amplifier to bias your amplifier

 

[wizardyhnr]

would someone provide me a detailed bias circuits or paper about the bias circuits.
thanks