Wideband Multi-Mode CMOS VCO Design Using Coupled Inductors

Abstract

Coupled inductors can create multiple resonant frequencies in a compact high-order resonator. Together with proper nonlinear active circuitry, such a high-order resonator realizes a multi-mode oscillator covering a wide frequency range. Compared with conventional switched-resonator-based approaches that consume the same chip area, the proposed coupled-inductor-based resonator results in larger quality-factor, and hence, lower oscillator phase noise. In the proposed multi-mode oscillator that uses the multi-port coupled inductors, mode switching is achieved using independent active cores without using lossy switches in the resonator path. The behavior of the multi-mode resonator as a multiport network in an oscillator, design trade-offs, and switching transient response of the multi-mode oscillator have been studied analytically. As a proof of concept, an integrated voltage-controlled oscillator (VCO) with a 1.28-6.06 GHz tuning range is designed and fabricated in a 0.13 m CMOS technology. The triple-mode VCO uses a sixth-order resonator based on three coupled inductors with a compact common-centric layout. Depending on the oscillation frequency, the VCO current consumption is automatically adjusted from 2.9 to 6.1 mA to achieve a low phase noise throughout the frequency range. The measured phase noises at 1 MHz offset from carrier frequencies of 1.76, 2.26, 3.3, 4.5, and 5.6 GHz are 119.3, 120.15, 118.1, 117, and 113.5 dBc/Hz, respectively. The chip area, including the pads, is 1 mm 1 mm and the supply voltage is 1.5 V.Index Terms-CMOS, phase noise, voltage-controlled oscillator (VCO), wideband.

A Low-Phase-Noise Wide-Tuning-Range Oscillator Based on Resonant Mode Switching

“…Based on these definitions, the Y matrix of the resonator in Fig. 14 is found to be (19) By solving , we can find two resonant frequencies: (20) in which…”

“…4, this "inductance switching" relaxes the constrains of phase noise at high frequency and power consumption at low frequency, and reduces current variation across the wide tuning range. Coupling LC tanks through transformer to get oscillation at two different frequencies was originally proposed by Bevilacqua et al [12], and there has been active research along this line to generate multiple frequency bands far apart [13]- [15], [18], [19], [23]. However, the impedance and quality factor of the resonator change significantly from mode to mode, which leads to inferior phase noise performance in one or more of the bands.…”

Analysis and Design of Digital Controlled Low-Phase-Noise CMOS LC_VCO

“…The outside control voltage V CTRL connects to the one end of the MOS varactors, with the change of the control voltage V CTRL , the value of the MOS varactors is changed and led to the change of oscillator frequency. The n and k are natural number, and n≥1, k≥1 [4] . …”

Integrated multi-tap transformer for reconfigurable multimode matching networks

“…1(b) and (c)), on the other hand, experience coupling between each turn of the primary and secondary windings and hence have a strong coupling interaction. By terminating both the primary and secondary winding of a transformer with a capacitor, a transformer can be used to create a high-order resonator, and hence have multiple resonant frequencies [4]. It is this property that will be utilized in the design of an input matching network of an LNA to achieve reconfigurable multi-band matching.…”

“…Hence, input matching is achieved in bands with center frequencies of ω H and ω L , simultaneously. According to [4], the ratio of the high and low resonant frequencies for this fourth-order resonator is given by:…”