Tuning Range Optimization of a Voltage Controlled Oscillator

Wireless communication growth has led to system requirement at short as well as long transmission range. Is has also promoted high demand of compact radio frequency (RF) circuit with low power design. As voltage control oscillator (VCO) is an important part of RF systems, following paper proposes a low power 30 GHz VCO. The preferred oscillator topology uses LC tank over ring oscillator because of its robust phase noise response. The proposed LC-VCO is validated through CAD simulation and shows a wide tuning range with lesser phase noise or power impact as compared to other proposed structures. The proposed LC-VCO is based on 90-nm CMOS process and consists of four MOS transistors and a LC-tank as the major constituents. The design has been kept simple so as to reduce the chip area and avoid any complex interconnect. Due to reduced load on the LC-tank achieved by the proposed structure, the power consumption recorded at a 1.8 V supply has was 0.38 mW. The achieved tuning range of the proposed system was 17%, and the phase noise was -105 dBc/Hz at 1 MHz offset. The performance of LC-VCO demonstrates the performance of low power compact (or mobile) transceiver system.