Volume 12, Issue 2 (2012)                   MJEE 2012, 12(2): 16-21 | Back to browse issues page

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Jafarzade S, Jannesari A. A High Dynamic Range Digitally-Controlled Oscillator (DCO) for All-Digital PLL Systems. MJEE. 12 (2) :16-21
URL: http://mjee.modares.ac.ir/article-17-533-en.html
1- Tarbiat Modares University, samira.
2- Tarbiat Modares University,
Abstract:   (4196 Views)
In this paper, a new high dynamic range Digitally-Controlled Oscillator (DCO) for All-DPLL systems is proposed. The proposed DCO is based on using a ΔΣ modulator as a Digital-to-Analog converter. Using ΔΣ DAC can provide a very high resolution (18-bit) control on the DCO. The ΔΣ DAC output is a 2-level pulse signal that needs to be filtered for cancelling the out of band shaped noise. The used ΔΣ modulator is a 4th order MASH ΔΣ modulator working with the OSR of 128 and the sampling frequency of 450MHz. the proposed DCO is used in a PLL to synthesize the frequency in the range of 1700MHz to 1800MHz for GSM-1800 application. The achieved phase noise for this PLL based synthesizer in whole the range is -115 dBc/Hz at the offset frequency of 500 kHz. The designed ADPLL including the DCO is simulated in ADS with 0.18µm CMOS technology.
Keywords: ADPLL, DCO, ΔΣ DAC, OSR, phase noise, OSR
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Received: 2004/07/4 | Accepted: 2015/03/1 | Published: 2015/11/22

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