Millimeter-wave voltage-controlled oscillators in 0.13-/spl mu/m CMOS technology

This paper describes the design of CMOS millimeter-wave voltage controlled oscillators. Varactor, transistor, and inductor designs are optimized to reduce the parasitic capacitances. An investigation of tradeoff between quality factor and tuning range for MOS varactors at 24 GHz has shown that the polysilicon gate lengths between 0.18 and 0.24 /spl mu/m result both good quality factor (>12) and C/sub max//C/sub min/ ratio (/spl sim/3) in the 0.13-/spl mu/m CMOS process used for the study. The components were utilized to realize a VCO operating around 60 GHz with a tuning range of 5.8 GHz. A 99-GHz VCO with a tuning range of 2.5 GHz, phase noise of -102.7 dBc/Hz at 10-MHz offset and power consumption of 7-15mW from a 1.5-V supply and a 105-GHz VCO are also demonstrated. This is the CMOS circuit with the highest fundamental operating frequency. The lumped element approach can be used even for VCOs operating near 100-GHz and it results a smaller circuit area.     

A 1-V 3.8 - 5.7-GHz wide-band VCO with differentially tuned accumulation MOS varactors for common-mode noise rejection in CMOS SOI technology

In this paper, a 1-V 3.8 - 5.7-GHz wide-band voltage-controlled oscillator (VCO) in a 0.13-/spl mu/m silicon-on-insulator (SOI) CMOS process is presented. This VCO features differentially tuned accumulation MOS varactors that: 1) provide 40% frequency tuning when biased between 0 - 1 V and 2) diminish the adverse effect of high varactor sensitivity through rejection of common-mode noise. This paper shows that, for differential LC VCOs, all low-frequency noise such as flicker noise can be considered to be common-mode noise, and differentially tuned varactors can be used to suppress common-mode noise from being upconverted to the carrier frequency. The noise rejection mechanism is explained, and the technological advantages of SOI over bulk CMOS in this regard is discussed. At 1-MHz offset, the measured phase noise is -121.67 dBc/Hz at 3.8 GHz, and -111.67 dBc/Hz at 5.7 GHz. The power dissipation is between 2.3 - 2.7-mW, depending on the center frequency, and the buffered output power is -9 dBm. Due to the noise rejection, the VCO is able to operate at very low voltage and low power. At a supply voltage of 0.75 V, the VCO only dissipates 0.8 mW at 5.5 GHz.     

Design of wide-band CMOS VCO for multiband wireless LAN applications

In this paper, a general design methodology of low-voltage wide-band voltage-controlled oscillator (VCO) suitable for wireless LAN (WLAN) application is described. The applications of high-quality passives for the resonator are introduced: 1) a single-loop horseshoe inductor with Q > 20 between 2 and 5 GHz for good phase noise performance; and 2) accumulation MOS (AMOS) varactors with C/sub max//C/sub min/ ratio of 6 to provide wide-band tuning capability at low-voltage supply. The adverse effect of AMOS varactors due to high sensitivity is examined. Amendment using bandswitching topology is suggested, and a phase noise improvement of 7 dB is measured to prove the concept. The measured VCO operates on a 1-V supply with a wide tuning range of 58.7% between 3.0 and 5.6 GHz when tuned between /spl plusmn/0.7 V. The phase noise is -120 dBc/Hz at 3.0 GHz, and -114.5 dBc/Hz at 5.6 GHz, with the nominal power dissipation between 2 and 3 mW across the whole tuning range. The best phase noise at 1-MHz offset is -124 dBc/Hz at the frequency of 3 GHz, a supply voltage of 1.4 V, and power dissipation of 8.4 mW. When the supply is reduced to 0.83 V, the VCO dissipates less than 1 mW at 5.6 GHz. Using this design methodology, the feasibility of generating two local oscillator frequencies (2.4-GHz ISM and 5-GHz U-NII) for WLAN transceiver using a single VCO with only one monolithic inductor is demonstrated. The VCO is fabricated in a 0.13-/spl mu/m partially depleted silicon-on-insulator CMOS process.     

Millimeter-wave VCOs with wide tuning range and low phase noise, fully integrated in a SiGe bipolar production technology

Millimeter-wave voltage-controlled oscillators (VCOs) are presented which are fully integrated in a SiGe bipolar production technology. The low-cost differential circuits have been designed and optimized for low phase noise and wide tuning range. As an example, by varying the bias voltage of the on-chip varactor, the oscillation frequency can be changed from 36 to 46.9 GHz (i.e., by 26%). In this wide frequency range, phase noise between -107 and -110dBc/Hz at 1-MHz offset frequency and single-ended voltage swing of about 0.95V/sub pp/ /spl plusmn/10% (differential: 1.9V/sub pp/) were measured. The circuit consumes 280mW at -5.5-V supply voltage. The high oscillation frequency and low phase noise at wide tuning range are record values for fully integrated oscillators in Si-based technologies. The basic oscillator was then extended by a cascode stage as an output buffer. Now the VCO performance is no longer degraded if nonperfectly terminated transmission lines are driven. Thus, the chip can be mounted in a low-cost socket; however, at the cost of increased phase noise and power consumption.     

Influence of novel MOS varactors on the performance of a fullyintegrated UMTS VCO in standard 0.25-μm CMOS technology

A novel MOS varactor design is compared to standard MOS varactors and its influence on the tuning range, phase noise, and pushing of a CMOS voltage-controlled oscillator (VCO) for UMTS is presented. Three fully integrated CMOS VCOs have been fabricated in standard 0.25-μm technology, two with different versions of a novel device, and one with a conventional nMOSFET as the tuning element. All of the fully integrated VCOs fulfill UNITS tuning and phase noise specifications with a power consumption of only 7.5 mW at a 2.5-V power supply. The new varactors outperform the nMOSFET by increasing the frequency tuning from ±7% to ±11% or ±13%, while the measured phase noise of all three VCOs is -117 dBc/Hz at a 1 MHz offset from a 4-GHz carrier     

SiGe Bipolar VCO With Ultra-Wide Tuning Range at 80 GHz Center Frequency

A SiGe millimeter-wave VCO with a center frequency around 80 GHz and an extremely wide (continuous) tuning range of 24.5 GHz ( ap 30%) is presented. The phase noise at 1 MHz offset is -97 dBc/Hz at the center frequency (and less than -94 dBc/Hz in a frequency range of 21 GHz). The maximum total output power is about 12 dBm. A cascode buffer improves decoupling from the output load at reasonable VCO power consumption (240 mW at 5 V supply voltage). A low-power frequency divider (operating up to 100 GHz) provides, in addition, a divided-by-four signal. As a further intention of this paper, the basic reasons for the limitation of the tuning range in millimeter-wave VCOs are shown and the improvement by using two (instead of one) varactor pairs is demonstrated.     

A 5.6 GHz Low Power Balanced VCO in 0.18 $mu$m CMOS

A 5.6 GHz balanced voltage-controlled oscillator (VCO) is designed and implemented in a 0.18 mum CMOS 1P6M process. It consists of two single-ended complementary Colpitts LC-tank VCOs coupled by two pairs of varactors. At the supply voltage of 1.2 V, the output phase noise of the VCO is -119.13 dBc/Hz at 1MHz offset frequency from the carrier frequency of 5.6 GHz, and the figure of merit is -190.29 dBc/Hz. Total VCO core power consumption is 2.4 mW. Tuning range is about 600 MHz, from 5.36 to 5.96 GHz, while the control voltage was tuned from 0 to 1.2 V.     

A study of digital and analog automatic-amplitude control circuitry for voltage-controlled oscillators

This paper presents both analog and digital automatic-amplitude control techniques for voltage-controlled oscillators (VCOs). These feedback mechanisms help to keep the VCOs at an optimum amplitude over temperature, process, and voltage variations. The VCOs were fabricated in a 50-GHz SiGe BiCMOS process. They use MOS varactors and achieve a 600-MHz tuning range in the 2-GHz band. The phase noise of the VCO with analog control was measured to be -99 dBc/Hz at 100-kHz offset from the carrier. The digital loop allows for a more optimized VCO core that achieves a phase noise of -108.5 dBc/Hz at 100-kHz offset in a low-gain mode. Techniques for suppressing the phase noise in regions of high gain are also presented. The VCOs draw between 4 and 8 mA from a 3.3-V supply.     

Frequency dependence on bias current in 5 GHz CMOS VCOs: impact on tuning range and flicker noise upconversion

The tuning curve of an LC-tuned voltage-controlled oscillator (VCO) substantially deviates from the ideal curve 1//spl radic/(LC(V)) when a varactor with an abrupt C(V) characteristic is adopted and the full oscillator swing is applied directly across the varactor. The tuning curve becomes strongly dependent on the oscillator bias current. As a result, the practical tuning range is reduced and the upconverted flicker noise of the bias current dominates the 1/f/sup 3/ close-in phase noise, even if the waveform symmetry has been assured. A first-order estimation of the tuning curve for MOS-varactor-tuned VCOs is provided. Based on this result, a simplified phase-noise model for double cross-coupled VCOs is derived. This model can be easily adapted to cover other LC-tuned oscillator topologies. The theoretical analyses are experimentally validated with a 0.25 /spl mu/m CMOS fully integrated VCO for 5 GHz wireless LAN receivers. By eliminating the bias current generator in a second oscillator, the close-in phase noise improves by 10 dB and features -70 dBc/Hz at 10 kHz offset. The 1/f/sup 2/ noise is -132 dBc/Hz at 3 MHz offset. The tuning range spans from 4.6 to 5.7 GHz (21%) and the current consumption is 2.9 mA.     

Fully integrated 5.35-GHz CMOS VCOs and prescalers

Two 5.35-GHz monolithic voltage-controlled oscillators (VCOs) and two prescalers have been fabricated in a digital 0.25-μm CMOS process. One VCO uses p⁺/n-well diodes, while the other uses MOS varactors, Q of 57 at 5.5 GHz and 0 V bias (low-Q condition) for a p ⁺/n-well varactor has been achieved. For an MOS varactor, it is possible to achieve a quality factor of 140 at 5.5 GHz. The tuning ranges of the VCOs are >310 MHz, and their phase noise is <-116.5 dBc/Hz at a 1-MHz offset while consuming ~7 mW power at V_DD=1.5 V. The low phase noise is achieved by using only PMOS transistors in the VCO core and by optimizing the resonator layout. The prescalers utilize a variation of the source-coupled logic. The power consumption is 4.1 mW at 1.5-V V_DD and 5.4 GHz. By widening the transistors in the first three divide-by-two stages, the maximum operating frequency is increased to 9.96 GHz at V_DD=2.5 V     

8-GHz CMOS quadrature VCO using transformer-based LC tank

A fully integrated quadrature VCO at 8 GHz is presented. The VCO is implemented using a transformer-based LC tank in 0.18 /spl mu/m CMOS technology, in which two VCOs are coupled to generate I-Q signals. The VCO is realized employing the drain-gate transformer feedback configuration proposed here. This makes use of the quality factor enhancement in the resonator using a transformer and the deep switching-off technique by controlling gate bias. By turning off switching transistors of the differential VCO core deeply, the phase noise performance is improved more than 10 dB. The measured phase noise values are -110 and -117 dBc/HZ at the offset frequencies of 600 kHz and 1 MHz respectively. The tuning range of 250 MHz is achieved with the control voltage from 0 to 1 V. The VCO draws 8 mA in two differential core circuits from 3 V supply. When the bias voltage goes down to 2.5 V, the phase noise decrease only 2 dB compared to that of 3 V bias. The VCO performances are compared with previously reported quadrature Si VCOs in 5/spl sim/12 GHz frequency range.     

A Low Phase-Noise X-Band MMIC VCO Using High-Linearity and Low-Noise Composite-Channel Al0.3Ga0.7N/Al0.05Ga0.95N/GaN HEMTs

A low phase-noise X-band monolithic-microwave integrated-circuit voltage-controlled oscillator (VCO) based on a novel high-linearity and low-noise composite-channel Al_0.3Ga_0.7N/Al_0.05Ga_0.95 N/GaN high electron mobility transistor (HEMT) is presented. The HEMT has a 1 mumtimes100 mum gate. A planar inter-digitated metal-semiconductor-metal varactor is used to tune the VCO's frequency. The polyimide dielectric layer is inserted between a metal and GaN buffer to improve the Q factor of spiral inductors. The VCO exhibits a frequency tuning range from 9.11 to 9.55 GHz with the varactor's voltage from 4 to 6 V, an average output power of 3.3 dBm, and an average efficiency of 7% at a gate bias of -3 V and a drain bias of 5 V. The measured phase noise is -82 dBc/Hz and -110 dBc/Hz at offsets of 100 kHz and 1 MHz at a varactor's voltage (V_tune)=5 V. The phase noise is the lowest reported thus far in VCOs made of GaN-based HEMTs. In addition, the VCO also exhibits the minimum second harmonic suppression of 47 dBc. The chip size is 1.2times1.05 mm²     

新型复合沟道Al0.3Ga0.7N/Al0.05Ga0.95N/GaN HEMT低相位噪声微波单片集成压控振荡器

设计并研制了一种新型复合沟道Al0.3Ga0.7N/Al0.05Ga0.95N/GaN HEMT(CC-HEMT)微波单片集成压控振荡器(VCO),且测试了电路的性能.CC-HEMT的栅长为1μm,栅宽为100μm.叉指金属-半导体-金属(MSM)变容二极管被设计用于调谐VCO频率.为提高螺旋电感的Q值,聚酰亚胺介质被插入在电感金属层与外延在蓝宝石上GaN层之间.当CC-HEMT的直流偏置为Vgs=-3V,Vds=6V,变容二极管的调谐电压从5.5V到8.5V时,VCO的频率变化从7.04GHz到7.29GHz,平均输出功率为10dBm,平均功率附加效率为10.4%.当加在变容二极管上电压为6.7V时,测得的相位噪声为-86.25dBc/Hz(在频偏100KHz时)和-108dB/Hz(在频偏1MHz时),这个结果也是整个调谐范围的平均值.据我们所知,这个相位噪声测试结果是文献报道中基于GaN HEMT单片VCO的最好结果.     

Low noise 5 GHz differential VCO using InGaP/GaAs HBT technology

The authors present the first InGaP/GaAs HBT differential VCOs with low phase noise performance. One is a cross coupled differential VCO, and the other is a Colpitts differential VCO. To achieve a fully integrated VCO, collector-base junction capacitance of HBT transistor is used for the frequency tuning varactor. The measured output frequency ranges of VCOs are 290 MHz and 190 MHz, and the phase noises at an offset frequency of 1 MHz are -118 dBc/Hz and -117 dBc/Hz respectively. The each VCO core dissipates 13.2 mW from a 3.5 V supply, and the output power is about -0.2 dBm. Concerned with cross coupled VCO, it shows the figure of merit of -179 dBc/Hz, which is the best result among the reported compound semiconductor FET and HBT VCOs.     

A Differentially-Tuned Voltage ControlledOscillator Using Symmetric Transformer

This letter proposes a new voltage controlled oscillator (VCO) topology that cancels common-mode noise by adoption of differential tuning varactor. To suppress common mode noise effectively, a symmetric three-coil transformer is proposed as a differential tuning resonator. The measured phase noise shows -128.7 dBc/Hz at 1 MHz offset frequency from the 1.2 GHz oscillation frequency. Over the whole frequency range, common-mode noise rejection is larger than 36 dB. Measured tuning range of the proposed VCO is about 204 MHz from the 1.18 GHz to 1.38 GHz while dissipating 1.2 mA at 1.8 V power supply.     

Low-power low-phase-noise differentially tuned quadrature VCOdesign in standard CMOS

This paper describes the design and optimization of VCOs with quadrature outputs. Systematic design of fully integrated LC-VCOs with a high inductance tank leads to a cross-coupled double core LC-VCO as the optimal solution in terms of power consumption. Furthermore, a novel fully differential frequency tuning concept is introduced to ease high integration. The concepts are verified with a 0.25-μm standard CMOS fully integrated quadrature VCO for zero- or low-IF DCS1800, DECT, or GSM receivers. At 2.5-V power supply voltage and a total power dissipation of 20 mW, the quadrature VCO features a worst-case phase noise of -143 dBc/Hz at 3-MHz frequency offset over the tuning range. The oscillator is tuned from 1.71 to 1.99 GHz through a differential nMOS/pMOS varactor input     

A low-voltage 40-GHz complementary VCO with 15% frequency tuning range in SOI CMOS technology

The design of a low-voltage 40-GHz complementary voltage-controlled oscillator (VCO) with 15% frequency tuning range fabricated in 0.13-/spl mu/m partially depleted silicon-on-insulator (SOI) CMOS technology is reported. Technological advantages of SOI over bulk CMOS are demonstrated, and the accumulation MOS (AMOS) varactor limitations on frequency tuning range are addressed. At 1.5-V supply, the VCO core and each output buffer consumes 11.25 mW and 3 mW of power, respectively. The measured phase noise at 40-GHz is -109.73 dBc/Hz at 4-MHz offset from the carrier, and the output power is -8 dBm. VCO performance using high resistivity substrate (/spl sim/300-/spl Omega//spl middot/cm) has the same frequency tuning range but 2 dB better phase noise compared with using low resistivity substrate (10 /spl Omega//spl middot/cm). The VCO occupies a chip area of only 100 /spl mu/m by 100 /spl mu/m (excluding pads).     

Fully Differential 5‐GHz LC‐Tank VCOs with Improved Phase Noise and Wide Tuning Range

In this paper, we propose two LC voltage‐controlled oscillators (VCOs) that improve both phase noise and tuning range. With both 1/f induced low‐frequency noise and low‐frequency thermal noise around DC or around harmonics suppressed significantly by the employment of a current‐current negative feedback (CCNF) loop, the phase noise in the CCNF LC VCO has been improved by about 10 dB at 6 MHz offset compared to the conventional LC VCO. The phase noise of the CCNF VCO was measured as ?112 dBc/Hz at 6 MHz offset from 5.5 GHz carrier frequency. Also, we present a bandwidth‐enhanced LC VCO whose tuning range has been increased about 250 % by connecting the varactor to the bases of the cross‐coupled pair. The phase noise of the bandwidth‐enhanced LC‐tank VCO has been improved by about 6 dB at 6 MHz offset compared to the conventional LC VCO. The phase noise reduction has been achieved because the DC‐decoupling capacitor Cc prevents the output common‐mode level from modulating the varactor bias point, and the signal power increases in the LC‐tank resonator. The bandwidth‐enhanced LC VCO represents a 12 % bandwidth and phase noise of ?108 dBc/Hz at 6 MHz offset.     

基于90nmCMOS工艺的低功耗宽带压控振荡器设计

A low power VCO with a wide tuning range and low phase noise has been designed and realized in a standard 90 nm CMOS technology. A newly proposed current-reuse cross-connected pair is utilized as a negative conductance generator to compensate the energy loss of the resonator. The supply current is reduced by half compared to that of the conventional LC-VCO. An improved inversion-mode MOSFET(IMOS) varactor is introduced to extend the capacitance tuning range from 32.8% to 66%. A detailed analysis of the proposed varactor is provided. The VCO achieves a tuning range of 27–32.5 GHz, exhibiting a frequency tuning range(FTR) of 18.4%and a phase noise of –101.38 d Bc/Hz at 1 MHz offset from a 30 GHz carrier, and shows an excellent FOM of –185d Bc/Hz. With the voltage supply of 1.5 V, the core circuit of VCO draws only 2.1 m A DC current.     

A 25-GHz ultra-low phase noise InGaP/GaAs HBT VCO

A 25-GHz monolithic voltage controlled oscillator (VCO) has been designed and fabricated in a commercial InGaP/GaAs heterojunction bipolar transistor (HBT) process. This balanced VCO has a novel topology using a feedback /spl pi/-network and a common-emitter transistor configuration. Ultra-low phase noise is achieved: -106 dBc/Hz and -130 dBc/Hz at 100kHz and 1-MHz offset frequency, respectively. To the authors' knowledge, this is the lowest phase noise achieved in a monolithic microwave integrated circuit (MMIC) VCO at such high frequency. The single-ended output power is -1 dBm. It can be tuned between 25.33GHz and 25.75GHz using the base-collector junction capacitor of the HBT as a varactor. The dc power consumption is 90mW for a 9-V supply. An excellent figure-of-merit of -195 dBc/Hz is obtained.