A CMOS quadrature VCO with subharmonic and injection-locked techniques

A 1-V quadrature voltage-controlled oscillator (QVCO) using subharmonic and injection-locked techniques (SHIL-QVCO) is presented. Instead of using the traditional transformer-coupling LC tank with a large area to implement the quadrature output, we use a frequency-doubled differential pair with an injection-locked method. The proposed QVCO is implemented with a TSMC 0.18-μm 1P6M CMOS process having a 1.4 × 0.67 mm² chip area. This QVCO has the advantages of low phase noise and low power consumption. Experimental results show that the QVCO has a phase noise of -126 dBc/Hz at an offset frequency of 1 MHz and a power consumption of 4.9 mW to achieve a 186 figure of merit. Moreover, a tuning frequency between 2.17 and 2.52 GHz can be obtained with a tuning voltage range of 0-1 V for the IEEE 802.15.4.