Building GPS receiver chip

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nuntha

Joined: 01 Apr 2004
Posts: 22

10 Jun 2004 10:47 Building GPS receiver chip

Hi ,
I am intending to build a GPS receiver chip in CMOS. As I am not a good system guy I have a system question.

The GPS received signal is -130dBm
Receiver NF = 10 (upto last IF amp)
noise BW = 2MHz (before despreading)
Output SNR at the last IF amp is -23dB {inorder to acheive 20dB SNR after despreading as the coding gain is 43dB)

Hence knowing the output SNR of the last IF amplier is -23dB what is the ouput signal level at the last IF amplifier in dBm?

Thanks in advance

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brmadhukar

Joined: 21 Jun 2002
Posts: 844
Helped: 29

12 Jun 2004 16:20 Re: Building GPS receiver chip

Hi,
I was involved very much in GPS for OEM both at RF/System level.

You need to know that the ADC requires sufficient input signal strength for quantization. Only the noise should be able to trigger the quantization.
So get a "quote" for you ADC levels. Then you will be able to decide the overall gain.

BR
Madhukar