LC VCO Design in candence for GSM 1800 and 900 Band.
时间：04-06
整理：3721RD
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Dear members,
Please help me find out answer to these basic questions about VCO:
1. In many IEEE papers I have seen that for GSM 900 Bnad, They make a VCO @ 3.8 GHz and then divide it by 4 to get the desired frequency in GSM band. Why?
2. How this division affect Phase noise. I mean if I make 1.8 GHz VCO and then Divide it by 2, Then which of them will be better?
3. How we select the frequency?
4. why not we can design 900 MHz itself although to get oscillator in CMOS VCO will be difficult.
Please Help me. I'm stuct to these questions from past many days.
Thanks
Please help me find out answer to these basic questions about VCO:
1. In many IEEE papers I have seen that for GSM 900 Bnad, They make a VCO @ 3.8 GHz and then divide it by 4 to get the desired frequency in GSM band. Why?
2. How this division affect Phase noise. I mean if I make 1.8 GHz VCO and then Divide it by 2, Then which of them will be better?
3. How we select the frequency?
4. why not we can design 900 MHz itself although to get oscillator in CMOS VCO will be difficult.
Please Help me. I'm stuct to these questions from past many days.
Thanks