A 4.2-5 GHz,low phase noise LC-VCO with constant bandwidth and small tuning gain

As the tuning frequency of an integrated LC-voltage controlled oscillator （LC-VCO） increases, it is difficult to co-design the active negative resistance core and the varactor to achieve wideband frequency range, low phase noise, constant bandwidth and small tuning gain together. The presented VCO solves the problem by designing a set of changeable varactor units. The whole VCO was implemented in a 0.18μm CMOS process. The measured result shows -120 dBc/Hz phase noise at 1 MHz offset. The measured tuning range is from 4.2 to 5 GHz and the tuning gain is 8-10 MHz/V. The VCO draws 4 mA from a 1.5 V supply voltage.     

采用PMOS底部电流源的低功耗电流自调整压控振荡器

This paper presents the design and implementation of a current self-adjusted VCO with low power consumption. In the proposed VCO, a bottom PMOS current source instead of a top one is adopted to decrease the tail noise. A current self-adjusted technique without additional external control signals is taken to ensure the VCO starts up in the whole band while keeping the power consumption relatively low. Meanwhile, the phase noise of the VCO at the low frequency （high Cvar） can be reduced by the technique. The circuit is implemented in 0.18 μm CMOS technology. The proposed VCO exhibits low power consumption of 〈1.6 mW at a 1.5 V supply voltage and a tuning range from 11.79 to 12.53 GHz. The measured phase noise at 1 MHz offset from the frequency 11.79 GHz is-104.7 dBc/Hz, and the corresponding FOM is -184.2 dBc/Hz.     

一种应用于无线局域网具有3.01-3.82 GHz频率范围和6.29%调谐增益变化的CMOS LC压控振荡器

A wideband low-phase-noise LC voltage-controlled oscillator （VCO） with low VCO gain （Kvco） vari- ation for WLAN fractional-N frequency synthesizer application is proposed and designed on a 0.13-μm CMOS process. In order to achieve a low Kvco variation, an extra switched varactor array was added to the LC tank with the conventional switched capacitor array. Based on the proposed switched varactor array compensation technique, the measured Kvco is 43 MHz/V with only 6.29% variation across the entire tuning range. The proposed VCO provides a tuning range of 23.7% from 3.01 to 3.82 GHz, while consuming 9 mA of quiescent current from a 2.3 V supply. The VCO shows a low phase noise of-121.94 dBc/Hz at 1 MHz offset, from the 3.6 GHz carrier.     

A 3.16–7 GHz transformer-based dual-band CMOS VCO

A dual-band, wide tuning range voltage-controlled oscillator that uses transformer-based fourth-order(LC) resonator with a compact common-centric layout is presented. Compared with the traditional wide band(VCO), it can double frequency tuning range without degrading phase noise performance. The relationship between the coupling coefficient of the transformer, selection of frequency bands, and the quality factor at each band is investigated. The transformer used in the resonator is a circular asymmetric concentric topology. Compared with conventional octagon spirals, the proposed circular asymmetric concentric transformer results in a higher qualityfactor, and hence a lower oscillator phase noise. The VCO is designed and fabricated in a 0.18- m CMOS technology and has 75% wide tuning range of 3.16–7.01 GHz. Depending on the oscillation frequency, the VCO current consumption is adjusted from 4.9 to 6.3 m A. The measured phase noises at 1 MHz offset from carrier frequencies of 3.1, 4.5, 5.1, and 6.6 GHz are –122.5, –113.3, –110.1, and –116.8 d Bc/Hz, respectively. The chip area, including the pads, is 1.20.62 mm2 and the supply voltage is 1.8 V.     

压控振荡器相位噪声、功耗和频率调谐特性的设计优化

To meet the requirements of the low power Zigbee system, VCO design optimizations of phase noise, power consumption and frequency tuning are discussed in this paper. Both flicker noise of tail bias transistors and up-conversion of flicker noise from cross-coupled pair are reduced by improved self-switched biasing technology, leading to low close-in phase noise. Low power is achieved by low supply voltage and triode region biasing. To linearly tune the frequency and get constant gain, distributed varactor structure is adopted. The proposed VCO is fabricated in SMIC 0.18-μm CMOS process. The measured linear tuning range is from 2.38 to 2.61 GHz. The oscillator exhibits low phase noise of -77.5 dBc/Hz and -122.8 dBc/Hz at 10 kHz and 1 MHz offset, respectively, at 2.55 GHz oscillation frequency while dissipating 2.7 mA from 1.2 V supply voltage, which well meet design specifications.     

一种新型低功耗CMOS压控振荡器采用电感偏置实现高性能的FoM

A novel voltage-controlled oscillator(VCO) topology with low voltage and low power is presented. It employed the inductive-biasing to build a feedback path between the tank and the MOS gate to enhance the voltage gain from output nodes of the tank to the gate node of the cross-coupled transistor. Theoretical analysis using timevarying phase noise theory derives closed-form symbolic formulas for the 1/f~2 phase noise region, showing that this feedback path could improve the phase noise performance. The proposed VCO is fabricated in TSMC 0.13 m CMOS technology. Working under a 0.3 V supply voltage with 1.2 m W power consumption, the measured phase noise of the VCO is –119.4 d Bc/Hz at 1 MHz offset frequency from the carrier of 4.92 GHz, resulting in an Fo M of 192.5 d Bc/Hz.     

应用于K波段使用了一种新的可变电感的20~25.5G的压控振荡器

A novel transformer-type variable inductor is proposed to achieve a wide tuning range at frequencies as high as K band. The variable inductor is designed, and an intuitive model is built to analyze its performance by HFSS. A lot of mathematical analysis is done in detail. A VCO using the proposed variable inductor is designed with TSMC 0.13 μm CMOS technology for verification. The frequency tuning range of the VCO depends on the proposed variable inductor. The phase noise of the VCO depends on the quality of the LC tank （including the proposed variable inductor and varactors）. So a specific AMOS varactor is implemented to improve its quality factor. The VCO is simulated at three typical TSMC fabrication comers （TT, FF, SS） to predict its measure results. The post simulation results shows that the VCO achieves a 20-25.5 GHz continuous tuning range. Its phase noise results at 1 MHz offset are -108.4 dBc/Hz and -100.5 dBc/Hz respectively at the tuning frequencies of 19.6 GHz and 25.5 GHz. The VCO draws only 3 to 6 mA from a 1.2 V power supply.     

应用于60-GHz无线通信的全差分锁相环频率综合器

A 40-GHz phase-locked loop(PLL) frequency synthesizer for 60-GHz wireless communication applications is presented. The electrical characteristics of the passive components in the VCO and LO buffers are accurately extracted with an electromagnetic simulator HFSS. A differential tuning technique is utilized in the voltage controlled oscillator(VCO) to achieve higher common-mode noise rejection and better phase noise performance. The VCO and the divider chain are powered by a 1.0 V supply while the phase-frequency detector(PFD)and the charge pump(CP) are powered by a 2.5 V supply to improve the linearity. The measurement results show that the total frequency locking range of the frequency synthesizer is from 37 to 41 GHz, and the phase noise from a 40 GHz carrier is –97.2 d Bc/Hz at 1 MHz offset. Implemented in 65 nm CMOS, the synthesizer consumes a DC power of 62 m W, including all the buffers.     

Fully integrated low phase noise multi-band LC-tank voltage controlled oscillator with switched-capacitor resonator

This paper presents the design and implementation of a fully integrated low noise multi-band LC-tank voltage-controlled-oscillator(VCO).Multi-band operation is achieved by using switched-capacitor resonator.Additional three-bit binary weighted capacitor array is also used to extend frequency tuning range in each band.To lower phase noise,two noise filters are added and a linear varactor is adopted.Implemented in a 0.18 μm complementary-metal-oxide-semiconductor(CMOS) process,the VCO achieves a frequency tuning range covering 2.26～2.48 GHz,2.48～2.78 GHz,2.94～3.38 GHz,and 3.45～4.23 GHz while occupies a chip area of 0.52 mm2.With a 1.8 V power supply,it draws a current of 10.9 mA,10.6 mA,8.8 mA,and 6.2 mA from the lowest band to the highest band respectively.The measured phase noise is-109～-120 dBc/Hz and-121～-131 dBc/Hz at a 1 MHz and 2.5 MHz offset from the carrier,respectively.     

基于SiGe BiCMOS技术的低功耗23G VCO

A 23 GHz voltage controlled oscillator(VCO) with very low power consumption is presented.This paper presents the design and measurement of an integrated millimeter wave VCO.This VCO employs an on-chip inductor and MOS varactor to form a high Q resonator.The VCO RFIC was implemented in a 0.18μm 120 GHz f_t SiGe hetero-junction bipolar transistor(HBT) BiCMOS technology.The VCO oscillation frequency is around 23 GHz,targeting at the ultra wideband(UWB) and short range radar applications.The core of the VCO circuit consumes 1 mA current from a 2.5 V power supply and the VCO phase noise was measured at around -94 dBc/Hz at a 1 MHz frequency offset.The FOM of the VCO is -177 dBc/Hz.     

单片CMOS UHF RFID阅读器中低噪声LC VCO的设计

设计了一种应用于单片CMOS超高频射频识别阅读器中的低功耗、低相位噪声LC VCO。根据超高频射频识别阅读器的系统架构和协议要求,对本振相位噪声要求做出详细讨论;采用LC滤波器和低压差调压器分别对尾电流源噪声和电源噪声进行抑制,提高了VCO相位噪声性能。电路采用IBM 0.18μm RF CMOS工艺实现,电源电压3.3 V时,偏置电流为4.5 mA,中心频率为1.8 GHz,在频偏1 MHz处,相位噪声为-136.25 dBc/Hz,调谐范围为30%。     

射频卫星电视天线电路中LC压控振荡器设计

本文设计了一款应用于卫星电视天线电路中低功耗、低相噪的宽带单片集成压控振荡器。该振荡器利用PMOS尾电流源和MIM电容阵列结构。在保证调谐范围的前提下,有效的降低了相位噪声。使得该压控振荡器实现了3.384GHz~4.022GHz频段的覆盖,在中心频率为3.7GHz时,100Hz和1MHz频偏处的相位噪声分别为-90.4dBc/Hz和-119.1dBc/Hz,工作电压下为1.8V,功耗仅为2.5mW。     

MOS varactors with n- and p-type gates and their influence on an LC-VCO in digital CMOS

The influence of the gate doping type of the MOS varactor on frequency tuning, phase noise, and frequency sensitivity to supply-voltage variations of a fully integrated inductance-capacitance voltage-controlled oscillator (LC-VCO) is presented. Three varactors in multifinger layout with shallow trench isolation (STI) are compared. The polysilicon gate is either entirely n- or p-doped or the fingers have alternating n and p doping. Differences in capacitance and quality factor are shown. Two identical VCOs with the varactors having n gates or np gates are realized. Homogenous doping increases the VCO tuning range to 1.31 GHz (/spl plusmn/20%) in comparison to 1.06 GHz (/spl plusmn/15%) obtained by mixed doping. However, mixed doping has the advantages of more linear VCO frequency tuning, lower close-in phase noise, and reduced maximum sensitivity to variations in supply voltage. Several varactor parameters are introduced. They allow prediction of the influence of varactors on the performance of a given VCO. With a current consumption of only 1 mA from a supply voltage of 1.5 V, both VCOs show a phase noise of -115 dBc/Hz at 1-MHz offset from a 4-GHz carrier and a VCO figure of merit of -185.3 dBc/Hz.     

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.     

A 0.5 V LC-VCO with improved varactor tuning technique for WSN

A 0.5 V LC-VCO implemented in 0.18 μm CMOS technology for wireless sensor network is described in this paper. An improved varactor tuning technique is proposed to decrease low frequency noise up-conversion and AM–FM phase noise of VCO, also it can increase Q of LC tank and reduce power consumption of VCO. For coarse tuning of VCO, it can increase the varactor control voltage variation range. For fine tuning of VCO, it can reduce the varactor nonlinearity. The measured tuning range is 4.58–5.26 GHz and power consumption is 2.2 mW. The measured phase noise is ?114 dBc/Hz at 1 MHz frequency offset from a 4.8 GHz carrier.     

Sub-1 V GPS band CMOS voltage-controlled oscillator with 29% tuning range

A sub-1 V 1.6 GHz voltage-controlled oscillator (VCO) was designed and fabricated using 0.35 μm CMOS technology. This LC-based VCO can operate at a supply voltage as low as 0.8 V. A top-biased PMOS, with capacitor connected in parallel, is used in order to reduce the noise contribution in the oscillated frequency even at low voltage supply. Moreover, an accumulation MOS varactor is adopted to provide 29% wider tuning frequency range compared with a diode varactor under same full tuning voltage. With a 0.8 V supply, this 1.6 GHz top-biased A-MOS VCO consumes 9 mW, included output buffer, with a measured phase noise of −109.3 dBc/Hz @ 600 kHz offset.     

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.     

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.     

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.