A monolithic AlGaN/GaN HEMT VCO using BST film varactor

A monolithic AlGaN/GaN HEMT voltage controlled oscillator (VCO) using barium strontium titanate (BST) MIM varactor is reported first time. The BST thin film was fabricated by RF magnetron sputtering. The fabrication process is fully compatible with the standard GaN MMIC integrated process. An output power of 17dBm and the phase noise of -75dBc/Hz (at 100kHz) and -110dBc/Hz (at 1MHz) are obtained while the bias of the drain is 8V and BST varactor voltage is 0V. The VCO exhibits 500MHz tunable frequency bandwidth at the central frequency of 6.42GHz while BST varactor voltage changed from 0V to 20V.