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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 指導教授 : 林志明 教授 學生 : 郭峻瑋. Outline. Abstract Introduction
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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 指導教授 : 林志明 教授 學生 : 郭峻瑋
Outline • 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 analytically 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.
Conventional VCO Fig. 1. Conventional LC-VCO circuit.
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 LC switching Fig. 2. Simultaneously LC switching VCO circuit.
Quality factors Q of those operating conditions are expressed following equations respectively. If loss resistance values of r1ow and rhigh are the same, a condition of keeping Q constant is
Loss resistances areexpressed 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.
Fig. 4. Resonant frequency switching characteristics simulated.
Experimental results and discussions • 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.