A low voltage multiband all-pMOS VCO was fabricated in a 0.18-/spl mu/m CMOS process. By using a combination of inductor and capacitor switching, four band (2.4, 2.5, 4.7, and 5 GHz) operation was realized using a single VCO. The VCO with an 1-V power supply has phase noises at 1-MHz offset from a 4.7-GHz carrier of -126 dBc/Hz and -134 dBc/Hz from a 2.4-GHz carrier. The VCO consumes 4.6 mW at 2.4 and 2.5 GHz, and 6 mW at 4.7 and 5 GHz, respectively. At 4.7 GHz, the VCO also achieves -80 dBc/Hz phase noise at 10-kHz offset with 2 mW power consumption.

A low-phase-noise and low-power multiband CMOS voltage-controlled oscillator

By utilizing a differential tunable active inductor for the LC-tank, a wide tuning-range CMOS voltage-controlled oscillator (VCO) is presented. In the proposed circuit topology, the coarse frequency tuning is achieved by the tunable active inductor, while the fine tuning is controlled by the varactor. Using a 0.18-mum CMOS process, a prototype VCO is implemented for demonstration. The fabricated circuit provides an output frequency from 500 MHz to 3.0 GHz, resulting in a tuning range of 143% at radio frequencies. The measured phase noise is from -101 to -118 dBc/Hz at a 1-MHz offset within the entire frequency range. Due to the absence of the spiral inductors, the fully integrated VCO occupies an active area of 150times300 mum2

A Wide Tuning-Range CMOS VCO With a Differential Tunable Active Inductor

A switched resonator concept, which can be used to reduce the size of multiple-band RF systems and which allows better tradeoff between phase noise and power consumption, is demonstrated using a dual-band voltage-controlled oscillator (VCO) in a 0.18-/spl mu/m CMOS process. To maximize Q of the switched resonator when the switch is on, the mutual inductance between the inductors should be kept low and the switch transistor size should be optimized. The Q factor of switched resonators is /spl sim/30% lower than that of a standalone inductor. The dual-band VCO operates near 900 MHz and 1.8 GHz with phase noise of -125 and -123dBc/Hz at a 600-kHz offset and 16-mW power consumption. Compared to a single-band 1.8-GHz VCO, the dual-band VCO has almost the same phase noise and power consumption, while occupying /spl sim/37% smaller area.

Switched resonators and their applications in a dual-band monolithic CMOS LC-tuned VCO

An oscillator with a high-order (>2) resonator has multiple stable modes of oscillations. The stable modes for one such oscillator, having a fourth-order resonator, are found using a nonlinear analysis. By using a proper nonlinear active topology and tank component values, the fourth-order oscillator can generate either of the two distinct frequencies f1 or f2. A method is introduced to dynamically switch between the stable modes of oscillations. It is shown that the phase noise of this fourth-order oscillator, when generating only one of its resonant frequencies, is comparable to the phase noise of a second-order oscillator using the same active topology and resonator quality factor. Furthermore, the fourth-order oscillator has better phase noise and/or higher tuning range in VCO implementations compared to the commonly used switched resonator oscillators. The claims have been verified experimentally through an integrated oscillator prototype with f1 = 2.4 GHz and f2 = 4.7 GHz fabricated in a standard 0.18 mum CMOS technology. The oscillator draws 1.89 mA current of 1.8 V supply. The 1 MHz offset phase noises of the fourth-order oscillator for f1 = 2.4 GHz and f2 = 4.7 GHz are -122.4 dBc/Hz and -123.4 dBc/Hz, respectively.

Frequency Switching in Dual-Resonance Oscillators

An integrated variable inductor is proposed using an on-chip transformer to obtain 2 inherent resonant modes for band-switching applications Employing such a variable inductor in a 018-mum CMOS process at a 1-V supply, a VCO is demonstrated to oscillate in 2 distinct frequency bands from 22 GHz to 36 GHz and from 107 GHz to 113 GHz The VCO measures phase noise of around -1355 dBc/Hz for the lower band and around -1265dBc/Hz for the upper band at 10-MHz offset while consuming 5mW and occupying an area of 04times08 mm2

A 1V Dual-Band VCO Using an Integrated Variable Inductor

A low voltage multi-band all PMOS VCO was fabricated in a 0.18-/spl mu/m CMOS process. By using a combination of inductor and capacitor switching, four band (2.4, 2.5, 4.7 and 5 GHz) operation was realized in a single VCO. The VCO with 1-V power supply has phase noises at 1-MHz offset of -126 dBc/Hz at 4.7 GHz and -134 dBc/Hz at 2.4 GHz, respectively. It has the lowest phase noise among the CMOS VCOs presented to date in all the bands. The VCO consumes 4.6 mW for 2.4 and 2.5 GHz, and 6 mW for 4.7 and 5 GHz operations, respectively.

Z. Li

Papers

A 1-V low phase noise multi-band CMOS voltage controlled oscillator with switched inductors and capacitors