An ultra low voltage 2.4GHz CMOS VCO

Abstract

A 2.4 GHz voltage controlled oscillator (VCO) with very low supply voltage is presented. The oscillator works at just 100 mV above the threshold voltage while fulfilling the phase noise requirements of Bluetooth. The very low supply voltage is achieved by replacing the current-source typically used with an inductor at the source node, thereby eliminating the DC-voltage drop. The oscillator measures a timing range of 13%, a current consumption of 2.8 mA, and a phase noise of -130 dBc/Hz at 3 MHz offset from the carrier frequency for a 0.7 V supply.