Realization of Novel Linear Sinusoidal VCOs

A few linear voltage-controlled sinusoidal oscillators using IC op-amps (OAs) and IC analogue multipliers (AMs) in conjunction with passive components are already known. In present communication two new linear VCO circuits are proposed. The proposed configurations employ two IC OAs, two IC AMs and fewer passive components as compared to any other circuit of this class reported earlier. In these oscillators the condition of oscillation (CO) and frequency of oscillation (FO) are independently tunable. It has also been shown here that both the proposed circuits are reducible to single OA linear VCOs. The workability of all these configurations has been experimentally tested and the practical result conform with the theoretically obtained values.     

一种S波段压控振荡器级联的注入锁定

针对压控振荡器(VCO)阵列注入锁定电路复杂和规模受限问题,提出一种S波段VCO阵列级联的新方法。通过在多个VCO之间加入耦合网络,将传统的单级注入改进为级联注入锁定,并通过网络级联方式实现级联级数的扩展。各级VCO之间通过耦合网络实现级联,首级VCO通过信号源参考信号进行锁定,次级VCO耦合前级VCO射频输出端信号进行锁定,每级均通过VCO电压调谐端进行注入。注入信号可锁定VCO输出频率,改善每级VCO输出相位噪声。通过级间耦合的形式,实现了一个微波源锁定多个VCO的输出。设计加工了2种级联注入VCO阵列,VCO的输出频率与注入信号频率相同,各级VCO相噪保持一致,当源相噪为-107.28 dBc/Hz时,各级VCO的输出相噪保持一致,为-105 dBc/Hz。该注入锁定方式电路简洁且成本低,未来有望应用在相控阵中。     

Selective metal parallel shunting inductor and its VCO application

The methodology to calculate the parasitic capacitances in differential symmetric inductors will be presented in this paper. Inspired by the proposed methodology, a method called selective metal parallel shunting (SMPS) can move f/sub Qmax/ onto the desired frequency without additional processing steps. Based on the proposed methodology, a customized program is developed to predict Q/sub max/s and f/sub Qmax/s of on-chip inductors. Differential symmetric inductors and spiral ones with planar, all metal parallel shunting (AMPS), and SMPS configurations have been implemented in a 1P4M 0.35-/spl mu/m CMOS process to verify the proposed method. Moreover, three 2.3-2.4 GHz voltage-controlled oscillators (VCOs) using planar, AMPS, and SMPS inductors, have also been realized. The phase noise of the VCO using SMPS inductors can be improved by 9.3 and 6 dB at 100-kHz offset frequency, respectively, compared to the VCOs using planar and AMPS inductors. The proposed SMPS technique can not only be applicable to VCO but also other RF circuits.     

L波段低相位噪声压控振荡器

对微波晶体管振荡器的相位噪声进行了分析。为达到压控振荡器的低相位噪声要求,采用了低电平振荡经放大后输出的设计方案。实现的微带压控振荡器工作于L波段. 相对电调带宽大于10％,不加介质谐振器其SSB相位噪声约达到一90dBC/Hz/10kHz;经加放大输出功率达到10mW以上,功率平坦度≤±0.7dB. 在-20～+60℃范围内正常工作,频率温度稳定性为6×10~(-5);本压控振荡器已应用于频率合成器中。     

Fully integrated dual-band VCOs with power controlled by body voltage in 130 nm CMOS/SOI for multi-standard applications

In this paper, the design of two VCOs for wireless multi-standard applications is presented. The oscillation frequencies are 5.2 and 3.3 GHz. These circuits have been produced using CMOS/SOI technology, with body voltage to control power consumption and phase noise performance. A new architecture for multi-standard applications is proposed. Five standards are covered by these structures: GSM (900 MHz), GPS (1.5 GHz), DCS (1.8 GHz), Bluetooth (2.45 GHz) and 802.11 a (5.8 GHz). The tuning range can vary from 2.45 to 5.8 GHz for the first VCO and from 850 MHz to 1.9 GHz for the second by using frequency divider. The main idea is to use only two MOS varactors to cover the entire frequency span. The first one is needed to get the matched frequency variation and the second to adjust the oscillation frequency. Such VCOs can be made thanks to CMOS/SOI technology advantages, high-Q passives and body voltage biasing that allow current change and power dissipation in the VCO core. These circuits were produced with a view to producing a single VCO covering all these standards. Switched resonators were therefore studied. At a frequency offset of 100 kHz, the single side band phase noise measurements were −89 and −93 dBc/Hz at 5.2 and 3.6 GHz respectively.     

All-active monolithic InP-based HBT VCO with tunable HEMT inductor

A novel HEMT-HBT VCO is presented; it is the first all-active analogue VCO demonstrated using InP HEMT-HBT integrated MMIC technology. The MMIC monolithically integrates an InP common-collector HBT oscillator with a tunable InP HEMT active inductor using selective MBE. The novel HEMT-HBT VCO can provide performance advantages over analogue VCOs such as the multi-vibrator, and has direct implications for high speed clock recovery circuits needed in InP based optoelectronic IC applications     

Variable inductance multilayer inductor with MOSFET switch control

A variable monolithic inductor having a stacked spiral inductor connected with MOSFET switches is proposed and fabricated in a 0.18 /spl mu/m, one-poly-six-metal (1P6M) standard CMOS process. By controlling a voltage of the MOSFET switch, the proposed three-stacked inductor demonstrates a continuously variable inductance of from 8 to 23 nH at 2.4 GHz, and due to its stacked structure, it takes less than 50% of the chip area compared with conventional single layer inductors. With its compact size and variable inductance feature, the proposed variable inductor is a prospective key component for the multiband RF circuits such as electrically controllable matching circuits and wide tuning range voltage controlled oscillators (VCOs).     

Calculation of Mutual Coupling between Two RLTs in Millimeter Wave VCO Waveguide Cavities with Mode Matching Methods

In the design of millimeter wave voltage control oscillators (VCOs), mutual coupling effect is of great importance for it influences the tuning and power characteristics of VCOs significantly. In this paper, mutual coupling between two in-line radial line transformers (RLTs) in rectangular waveguide cavities of millimeter wave VCOs has been evaluated with mode matching methods. Mutual coupling characteristics varying with various parameters of resonate cavity such as the distance between two diodes, the position of sliding short, the radii of bias pins, the radii of RLTs, and the height of diodes are presented. Some useful conclusions concerning two RLTs configuration have been derived, which is helpful to design millimeter wave VCO of this structure.     

Voltage-controlled oscillators up to 98 GHz in SiGe bipolar technology

In this paper, two fully integrated voltage-controlled oscillators (VCOs) in a 200-GHz f/sub T/ SiGe bipolar technology are presented. The oscillators use on-chip transmission lines at the output for impedance transformation. One oscillator operates up to 98 GHz and achieves a phase noise of -85dBc/Hz at an offset frequency of 1 MHz. It can be tuned from 95.2 to 98.4 GHz and it consumes 12 mA from a single -5-V supply. The second oscillator operates from 80.5 GHz up to 84.8 GHz with a phase noise of -87dBc/Hz at 1-MHz offset frequency. The output power of both circuits is about -6dBm.     

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.     

RF CMOS Varactors for 2 GHz Applications

CMOS varactors are important components for the integration of tunable RF filters and VCOs. This paper presents a performance evaluation and comparison of three different types of CMOS varactors based on measurements. The tested varactor types are: (i) p⁺-to-n-well junction, (ii) standard mode nMOS, and (iii) accumulation mode nMOS. The performance of each varactor type with respect to capacitance ratio and quality factor Q is evaluated at 2 GHz. Further, it is shown how these varactor types must be configured in LC-tank circuits for optimum performance. Finally, the three varactor types are compared and it is concluded that the Standard Mode nMOS type seems to the best choice for RF applications.     

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     

Large-signal analysis of MOS varactors in CMOS -G/sub m/ LC VCOs

MOS varactors are used extensively as tunable elements in the tank circuits of RF voltage-controlled oscillators (VCOs) based on submicrometer CMOS technologies. MOS varactor topologies include conventional D = S = B connected, inversion-mode (I-MOS), and accumulation-mode (A-MOS) structures. When incorporated into the VCO tank circuit, the large-signal swing of the VCO output oscillation modulates the varactor capacitance in time, resulting in a VCO tuning curve that deviates from the dc tuning curve of the particular varactor structure. This paper presents a detailed analysis of this large-signal effect. Simulated results are compared to measurements for an example 2.5-GHz complementary -G/sub m/ LC VCO using I-MOS varactors implemented in 0.35-/spl mu/m CMOS technology.     

Development of 60-GHz front-end circuits for a high-data-rate communication system

Recent results from a Swedish program for development of 60-GHz monolithic microwave integrated circuits (MMICs) for high-data-rate communication links are presented. Front-end circuits such as mixers, amplifiers, frequency multipliers, IF amplifiers with gain control, and voltage-controlled oscillators (VCOs) have been realized utilizing GaAs PHEMT and MHEMT technologies. A newly developed 7.5-GHz coupled Colpitt VCO shows a minimum phase noise of -95 dBc at 100 kHz offset. A second-harmonic 14-GHz VCO shows a minimum phase noise of less than -90 dBc at 100 kHz. A novel balanced 7-28-GHz MMIC frequency quadrupler is described and compared with a single-ended quadrupler at the same input frequencies. To demonstrate its feasibility and potential application, the quadrupler is combined with the Colpitt VCO and the output characteristics of the resulting 30-GHz MMIC source are measured. A three-stage MHEMT wide-band amplifier covering 43-64 GHz with a gain of 24 dB, a minimum noise figure of 2.5 dB, and a passband ripple of 2 dB is also described. In future 60-GHz systems for mass markets where cost is of utmost importance, Si-based technologies, especially CMOS, are highly interesting. Some recent circuit results based on a 90-nm CMOS technology are also reported.     

A Triple-Tuned Ultra-Wideband VCO

We have already proposed a triple-tuned voltage-controlled oscillator (VCO) for achieving an ultra-wideband characteristic. The triple-tuned VCO consists of an active device and three tuned circuits. The fabricated VCO has achieved the oscillation bandwidth of 5.6-16.8 GHz and the phase noise of -114.9 dBc/Hz +/-2.9 dB at 1-MHz offset from the carrier. In this paper, for the first time, the conditions that the VCO achieves the ultra-wideband characteristic are clarified by formulation and simulation. It is also clarified that a transistor of the larger emitter size is suitable for the wideband VCO. In addition, the performances of the proposed VCO are compared with other reported wideband VCOs. As a result, it is shown that the proposed VCO has achieved the lowest figure of merit in the C-Ku-band.     

On the use of MOS varactors in RF VCOs

This paper presents two 1.8 GHz CMOS voltage-controlled oscillators (VCOs), tuned by an inversion-mode MOS varactor and an accumulation-mode MOS varactor, respectively. Both VCOs show a lower power consumption and a lower phase noise than a reference VCO tuned by a more commonly used diode varactor. The best overall performance is displayed by the accumulation-mode MOS varactor VCO. The VCOs were implemented in a standard 0.6 μm CMOS process     

Ring-Based Triple-Push VCOs With Wide Continuous Tuning Ranges

This paper proposes a new ring-based triple-push voltage-controlled oscillator (VCO) architecture to achieve a wide tuning range and high operating frequencies. Two ring-based triple-push VCOs, one with a continuous frequency tuning range of 0.2-34 GHz, fabricated in 0.13- mum CMOS, and the other with a range of 0.1-65.8 GHz, fabricated in 90-nm CMOS, are presented in this paper. These two VCOs demonstrate that the proposed VCO architecture can achieve a very wide continuous tuning range, up to millimeter-wave frequencies, without any device-switching operations. In addition to the wide tuning range, the chip area of the proposed VCO is very small, allowing integration into a phase-locked loop. The power consumptions of the 0.2-34- and 0.1-65.8-GHz VCOs are 2-70 mW from a 2-V supply voltage, and 1.2-26.4 mW from a 1.2-V supply voltage, respectively. The fundamental and second harmonic rejections are better than 15 dB for both VCOs.     

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.     

A new robust capacitively coupled second harmonic quadrature LC oscillator

A study of some reported superharmonic LC quadrature voltage-controlled oscillator (LC-QVCO) is performed in which it is shown that robustness of the quadrature oscillation varies depending on the coupling configuration. Next, a new superharmonic LC-QVCO is proposed in which the common source node in either of two identical cross-connected LC-VCOs is coupled via a capacitor to the node common between the two varactors in the LC-tank of the other LC-VCO. As a result of connecting common mode nodes, the currents flowing through the two coupling capacitors are comprised of only the even harmonics. In the proposed coupling configuration there exists a closed loop through which the second harmonic signals circulate. A qualitative argument is presented to justify the robustness of the quadrature nature of the proposed QVCO by applying the Barkhausen phase criterion to the second harmonic signals in the loop. Since the coupling devices are only two capacitors, no extra noise sources and power consumption are added to the core VCOs. A Monte-Carlo simulation showed that the phase error of the proposed QVCO caused by device mismatches is no more than 1°. Also, generalizing this method to several numbers of VCOs in a loop, multiphase signals can be generated. The proposed circuits were designed using a 0.18-μm RF CMOS technology and simulation results are presented.     

CMOS second-harmonic quadrature voltage controlled oscillator using substrate for coupling

In this work, a new circuit configuration for second-harmonic quadrature voltage controlled oscillator (QVCO) with CMOS technology is proposed. The proposed QVCO is made by coupling two identical cross-connected VCOs. The coupling elements (two resistors and two capacitors) do not increase the power consumption of the core VCOs and do not disturb the resonant frequency of the tank circuit in the core VCOs and also, according to the simulations the coupling elements do not adversely affect the phase noise. The role of the substrate terminal of cross-connected MOSFETs of the core oscillators as common mode nodes is demonstrated. Using this node for coupling makes it possible to eliminate the tail transistors in the core oscillators and therefore the circuit can operate with supply voltages as low as 0.5 V. Using the same method to couple more than two core oscillators, results in a multiphase VCO.