Design of a three-stage ring-type voltage-controlled oscillator with a wide tuning range by controlling the current level in an embedded delay cell |
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Authors: | Won-tae Lee Jaemin Shim Jichai Jeong |
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Affiliation: | 1. Department of Computer and Radio Communication Engineering, Korea University, 145, Anam-Ro, Sungbuk-ku, Seoul 136-713, Korea;2. Department of Brain and Cognitive Engineering, Korea University, Korea University, 145, Anam-Ro, Sungbuk-ku, Seoul 136-713, Korea |
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Abstract: | This paper presents a new design for a three-stage voltage-controlled differential ring oscillator embedded with a delay cell for a wide tuning range from 59 MHz to 2.96 GHz by adjusting the current level in the delay cell. The ring oscillator consists of a voltage-to-current converter, coder circuit, three-stage ring with delay cells, and current monitoring circuit to extend the tuning range of the proposed voltage-controlled oscillator. Each functional block has been designed for a minimum power consumption using the TSMC 0.18 μm CMOS technology. We simulate the performances of the proposed voltage-controlled oscillator in terms of phase noise, power consumption, tuning range, and gain. Our simulation results show that the proposed oscillator has the linear frequency–voltage characteristics over a wide tuning range. At each tuning range (mode), the calculated phase noise of the proposed ring oscillator at each tuning range (mode) was −87, −85, −81, and −79 dBc/Hz at a 1 MHz offset from the center frequency. The DC power of the proposed voltage-controlled oscillator consumed 0.86–3 mW under a 1.8 V supply voltage. |
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Keywords: | CMOS RC oscillators Voltage to current converter Phase noise Ring oscillator Voltage controlled oscillator (VCO) |
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