A compact CMOS 2V low-power direct-conversion quadrature modulator merged with quadrature voltage-controlled oscillator and RF amplifier for 1.9GHz RF transmitter applications

Abstract

A compact 2V CMOS low-power direct-conversion quadrature modulator merged with quadrature voltage-controlled oscillator (VCO) and RF amplifier for 1.9GHz RF transmitter applications is described. The circuit is implemented by using 0.35 mu m DPTM CMOS technology and dissipates only 19mW under 2V power supply voltage. The low power operation is enabled by the current reuse technique used among quadrature modulator, quadrature VCO, and RF amplifier. Due to small signal path mismatch, the unwanted lower sideband is below -50dB when the 0dB normalized desired upper sideband is set at 1.97GHz. Moreover, the LO feedthrough, second-order intermodulation, and third-order intermodulation are less than -50dB. The tuning range of the quadrature VCO is 270MHz from 1.95GHz to 2.22GHz.