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A Dynamic GHz-Band Switching Technique for RF CMOS VCO
K, Shibata. ; H, Sato. ; N, Ishihara. ;Silicon Monolithic Integrated Circuits in RF Systems, 2007 Topical Meeting on
Jan.10-12 2007 Page(s):273 - 276
積體電路設計研究所積體電路設計研究所
指導教授 指導教授 : : 林志明 教授林志明 教授
學生 學生 : : 郭峻瑋郭峻瑋
OutlineOutline
• Abstract
• Introduction
• Conventional VCO
• VCO circuit using simultaneous LC switching
• Experimental results and discussions
• Conclusion
Abstract• To get wide band switching, it has been clarified a
nalytically that keeping Q constant is important to configure the circuit.
• a dual band VCO circuit has been designed by using a 0.13-μm standard CMOS process technology and succeeded in switching the band dynamically from 2 to 4 GHz .
Introduction
• A circuit which can switch capacitors and inductors simultaneously has been suggested.
• The chip fabricated was operated with a power supply voltage of 1.7 V.
Where L: inductance for resonation, Cc: constant capacitance setting the operation band, Cvo: varactor capacitance, C0: total capacitance.
Value of Q is decreased by increasing value of Co.
VCO circuit using simultaneous VCO circuit using simultaneous LC switching LC switching
Fig. 2. Simultaneously LC switching VCO circuit.
Quality factors Q of those operating conditions areexpressed following equations respectively.
If loss resistance values of r1ow and rhigh are the same, acondition of keeping Q constant is
• Loss resistances are expressed by following equations respectively.
• If L1 is equals to L2 to simplify the discussion, a condition that r1ow becomes equal to rhigh to keep value of Q constant is
Low frequency (SW1: ON, and SW2: OFF).
High frequency (SW1: OFF, and SW2: ON).
Fig. 3. Equivalent circuit considered loss resistances.
Experimental results and Experimental results and discussionsdiscussions
• Signal output buffers which can drive 50 Ω are added to the core LC-VCO circuit.
• The sizeis 1.8 mm x 1.7 mm.
• The chip packaged was measured by using a spectrum analyzer.
• FOM and FOMT, were calculated using following equations.
• L{Δf } is measured phase noise at the frequency offset Δf from the carrier at fo, and PDC is the measured dc power dissipation in mW. And, FTR is frequency tuning range.