LNA power gain in RFIC 0.18um processor

sjyatou · Dec 18, 2003

How can I improve the LNA power gain ?expect DC current ,or device size?what can I do for better gain

panpan · Dec 18, 2003

make accurate impedance match

cbirdman · Dec 18, 2003

Select a loading inductor with a higher Q value can improve power gain.
Or use cascode type to increase isolation.
Last, increase current also can improve some performance

eladg · Dec 18, 2003

sjyatou said:
How can I improve the LNA power gain ?expect DC current ,or device size?what can I do for better gain

put 2 stage

StoppTidigare · Dec 18, 2003

Hi all just one comment to all the answers.
Conjugate impedance match at LNA is not the thing to do. An LNA should be optimized towards noise figure. Its important that the first stage is the best in point of noise figure.

I don't understand the comment by cbirdman to

Select a loading inductor with a higher Q value can improve power gain.

Please explain, do yo mean that one shouldn't go for a conjugate match at the output ?
Regards,
StoppTidigare

sjyatou · Dec 19, 2003

to StoppTidigare:

Yes ,I agree with you !
The noise figure of LNA is crucial for the receiver ,but meawhile the mixer
contribution to the system noise figure depent on the LNA gain value,so
the LNA gain is too important for the receivers.

sjyatou · Dec 19, 2003

I think high Q inductor ,have low loss,because theoretically capacitor and
inducor do not consume power ,but in practice have parasitical resistor ,it
consume power.
About matching ,I think that is necessary for LNA design ,even for RF

brmadhukar · Dec 19, 2003

Hi,
There are two types of matching.
a) for NF
b) for Power

The difference in power gain will be normall around 0.5-1dB. This may not be really significant in many applications. So it is better to go for noise matching always.

Use ceramic single layer High Q capacitors
Low loss inductors

Madhukar

cbirdman · Dec 21, 2003

Because the LC tank parallel resistance in resonant frequency is propotional to Q value of inductor.

sjyatou · Dec 22, 2003

to Madhukar

1)For noise matching ,how to noise matching in Spectra RF or ADS .

2)When the circuits is for the noise matching ,the S11 may be larger -10dB, which is the request commonly.

thank you

sjyatou

Canosa · Jan 23, 2010

sjyatou said:
to Madhukar

1)For noise matching ,how to noise matching in Spectra RF or ADS .

2)When the circuits is for the noise matching ,the S11 may be larger -10dB, which is the request commonly.

thank you

Hi!

Using ADS is very simple to do that.
1)To get the input matching network for NFmin:

a) You just have to extract NFmin of the device vs Vbias for the working frequency.
b) Next with NFopt reflection coefficient uses smith chart utility from the ADS palette to generate the input matching network automatically.
c) Then choose the right input matching network to generate NFopt reflection coefficient to get NFmin.
d) Build ADS... to put the input impedance matching on schematic... and... you are done!

If you have any doubts... reply...

2) -10 dB it's okay! If you have a filter or an antenna behind the LNA in the receiver chain and coefficient input reflection, S11; with more than -10 dB can generate distortion on filter characteristics.
Normally you have tradeoff between NF, Power and S11. So choosing the right device size and bias is important.

LNA power gain in RFIC 0.18um processor

sjyatou

Junior Member level 2

panpan

Newbie level 4

cbirdman

Newbie level 5

eladg

Full Member level 3

StoppTidigare

Full Member level 2

sjyatou

Junior Member level 2

sjyatou

Junior Member level 2

brmadhukar

Advanced Member level 3

cbirdman

Newbie level 5

sjyatou

Junior Member level 2

Canosa

Junior Member level 2

Similar threads

LNA power gain in RFIC 0.18um processor

Junior Member level 2

Newbie level 4

Newbie level 5

Full Member level 3

Full Member level 2

Junior Member level 2

Junior Member level 2

Advanced Member level 3

Newbie level 5

Junior Member level 2

Junior Member level 2

Similar threads

Privacy & Transparency

Privacy & Transparency