digital lna analog lna
what is the digital LNA , is it gain programmble LNA
or the amp used in the high speed digital interface
khouly
Thank khouly! Could you tell me more detail about principles of design, or any concern documents, ebooks. I need them very much.
digital LNA, this is a new concept, would y please tell me what is your digital LNA at first, because the LNA is analog in my mind
I don't think it's a new concept, rather marketing buzz-words for moving the ADC closer to the antenna.
yeah LNA is analog , but i have seen in some chips that the LNA gain can be changed digitally
but the LNA still analog part
in high speed digital interfaces the frist AMP in the receiver is an analog also , but the signal is digital one , but the LNA still analog
khouly
in real world,the signal is analog,so the lna must not be digital.
i think what you said is seem as SDR
Hi All....!
What i beleive is the very use of Low Noise Amplifier (LNA) is for RF/MW app'ns. whereas 'Digital' would mean few 10s of MHz, where in noise is definitely not as crutial a parameter. Imean one would not require a specialised LNA for digital applications in the first place...!
Bye,
Sai
Digital RF LNA
is the term for an amplifier intended to be in front of a sample/hold stage.
A sample/hold stage only pass the signal for a small fraction of the sampling period. So the amount of signal energy passed to the sampling cap to the hold amplifier noise is bad in comparison to a simple mixer stage. In a mixer the signal is multiplied by a rectangular signal. So high frequency noise folding gets limited.
So comparison between a sampling mixer and a conventional mixer shows two independend drawbacks for the sampling stage.
1. Small signal aparature
2. High noise folding
This could only be overcome if the frontend signal amplification is significant higher for RF sampling systems. So the power is higher and the overall linearity for the same system NF is lower. This is an system effect of the equivalent mixing function of the convential mixer and the sampling stage.
I invite everyone to argument a counterexample!
As i read, the trend in wireless communication is going digital. Traditional RF architectures have ussually been implemented using maily analog approaches for down conversion, modulation and filtering. Recent design and process technologies have allowed the conversion from RF to digital to occur within the radio before the baseband. (microwave journal 09.2006)
I think that, LNA with programmable gain is analog LNA with digital interfaces. That is an intermediate step between analog and digital LNA.