Implementación de un LC-VCO con un AGC incorporado para aplicaciones de Radar (Implementation of an LC-VCO with Built-in AGC for Oceanographic Radar Applications)

William Toro (, Juan Velez (, Mauricio Pardo (

1Universidad Del Norte

This paper appears in: Revista IEEE América Latina

Publication Date: April 2016
Volume: 14,   Issue: 4 
ISSN: 1548-0992

This paper presents a LC Voltage-Controlled Oscillator (LC-VCO) with an incorporated Automatic Gain Control (AGC) unit. The LC oscillator is based on the BJT cross-coupled pair topology with tuning varactors and a dual supply source so that the tuning range is maximized. The trade-off between the quality factor, tuning range and number of varactors in parallel is analyzed. In addition, the stability of the AGC system is proven by the estimation of the gain and phase margin. Finally, the phase noise (PN) LC-VCO is estimated using the Leeson model. The oscillator shows a tuning range from 4.3MHz to 6MHz (about 330,000 ppm) and an estimated phase noise of -117.2dB /Hz@ 1kHz. The system shows an improvement of 6dB compared to the same VCO without gain control. The system consumes 47mW of power from a 3V supply.

Index Terms:
VCO,AGC,phase noise,tuning,quality factor,varactor,stability   

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