Design of multistandard adaptive voltage-controlled oscillators

A multistandard/multiband adaptive voltage-controlled oscillator (VCO) satisfying the phase-noise requirements of both second- and third-generation wireless standards is described in this paper (1.8-GHz DCS1800, 2.1-GHz wide-band code division multiple access, and 2.4-GHz wireless local area network, Bluetooth, and digital enhanced cordless telecommunications standards). The design procedure for the VCO is based on an adaptive phase-noise model. A factor of 12 reduction in power consumption with a phase-noise tuning range of 20 dB is demonstrated by adapting the VCO bias to the desired application. The VCO achieves -123-, -110-, and -103-dBc/Hz phase noise at 1-MHz offset in a 2.1-GHz band at supply currents of 6, 1.2, and 0.5 mA, respectively     

Self-noise cancelling technique for voltage-controlled oscillators

A noise cancellation technique for a voltage-controlled oscillator (VCO), which does not require a reference clock, is presented. The key idea is to employ a feedback loop around a VCO using a voltage-controlled delay line and an integrator which detects and cancels the noise of the VCO. Unlike conventional VCOs, the output frequency of the proposed VCO is indirectly changed using the voltage-controlled delay line. The proposed idea is verified in theory and simulation.     

A voltage-controlled tunable distributed RC filter

A new type of voltage-controlled tunable distributed RC filter is described by the type metal-insulator-semiconductor-metal. Tuning is attained by field-effect control of the capacitance by a bias voltage, independently of the distributed resistance. Results are given for evaporated thin-film NiCr-Y/SUB 2/O/SUB 3/-CdS-Al filters, together with illustrative applications to tunable RF networks.     

CMOS active transformers and their applications in voltage-controlled quadrature oscillators

This paper introduces CMOS active transformers synthesized using MOS transistors only. The proposed active transformers are evolved from their active inductor counterparts and offer a number of attractive characteristics as compared with spiral transformers including a tunable coupling ratio, large and tunable self and mutual inductances, high and tunable quality factors, and a small silicon area consumption. The characteristics of the proposed active transformers including the tunability of the self and mutual inductances, power sensitivity, noise, and quality factor are investigated both analytically and numerically using simulation. The application of the proposed active transformers is exemplified using a 1.6 GHz quadrature VCO implemented in TSMC-0.18 μm 1.8 V CMOS technology and analyzed using SpectreRF from Cadence Design Systems with BSIM3v3 device models. The total transistor area and power consumption of the VCO are 107 μm² and 10.8 mW, respectively. The phase noise of the VCO is −114.6 dBc/Hz at 1 MHz frequency offset.     

A voltage-controlled tunable thin-film distributed RC notch filter

Notch filters are widely used in communication and instrumentation systems not only for eliminating undesired frequencies and for measuring transient harmonic distortions, but also as central components of selective filters and oscillators in feedback arrangements. This paper describes the characteristics of a thin-film distributed RC (DRC) notch filter made from Au/TaN/Y-doped BaTiO₃ (Y-BT)/Pt. The dielectric (Y-BT) and resistive (TaN) films were grown by pulsed laser deposition (PLD). A notch frequency of 2.8 MHz and notch depth of -76.7 dB were measured from zero with a notch resistance (R_N) of 34 Ω. The experimental optimum notch parameters of α=R/R_N =19.7 and x_n=ω/ω₀=33.0 were obtained. Tunability of the notch frequency was observed with an applied DC bias voltage     

Minimum length for distributed oscillators

Lyapunov stability theory predicts a minimum line length for the existence of active oscillations on a distributed circuit model of the superconductive tunnel junction strip line. Experiments on a lumped ladder-line model give close quantitative agreement with this prediction.     

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.     

Low voltage low noise open loop automatic amplitude control for voltage-controlled oscillators

This paper presents a low voltage low noise open loop automatic amplitude control method for voltage-controlled oscillators (VCO’s). In this method a feedback mechanism keeps the VCO at its optimum amplitude over temperature and process variations and then the loop is broken to avoid noise injection form the control circuitry to the VCO. The loop does not add extra noise to the VCO. Based on the proposed method, a low voltage low noise LC-VCO was designed for a low phase noise application in TSMC 0.18 micron RFCMOS technology. Simulations show considerable improvement in the phase noise with the application of the proposed method.     

Low-power voltage-controlled oscillators in 90-nm CMOS using high-quality thin-film postprocessed inductors

Wafer-level packaging (WLP) technology offers novel opportunities for the realization of high-quality on-chip passives needed in RF front-ends. This paper demonstrates a thin-film WLP technology on top of a 90-nm RF CMOS process with one 15-GHz and two low-power 5-GHz voltage-controlled oscillators (VCOs) using a high-quality WLP or above-IC inductor. The 5-GHz VCOs have a power consumption of 0.33 mW and a phase noise of -115 dBc/Hz and -111 dBc/Hz at 1-MHz offset, respectively, and the 15-GHz VCO has a phase noise of -105 dBc/Hz at 1-MHz offset with a power consumption of 2.76 mW.     

Single-transistor oscillators with distributed RC networks

Three single-transistor oscillators with distributed RC networks are presented. The design problem of these circuits is investigated, and generalised diagrams are given. The method may be applied also to other types of oscillators.     

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.     

Issues on the design and implementation of radio frequency CMOS LC tank voltage-controlled oscillators

This paper is a general tutorial on the design and implementation of integrated submicron CMOS voltage-controlled oscillators based on LC resonator tanks. Although special reference to phase noise reduction is made, the discussion also includes issues such as power consumption, oscillator reliability and adaptivity together with tuning range. Important guidelines on oscillator and LC tank design are discussed, with emphasis on the fact that reduction of noise up-conversion is as important as the reduction of the noise magnitude coming from the various components in the oscillator.     

Comparative study of gigahertz CMOS LC quadrature voltage-controlled oscillators with relevance to phase noise

This review paper presents a comparative study of published integrated submicron CMOS quadrature voltage-controlled oscillator designs, based on LC resonator tanks operating at gigahertz frequencies. Although special reference to phase noise reduction is made, the comparison also concerns issues such as power consumption, tuning range and the phase accuracy of the quadrature signals. The effect of supply voltage reduction on the choice of the oscillator topology is also included in the discussion.     

A 1.8-V distributed voltage-controlled oscillator module for 5.8-GHz ISM band

This letter presents the design and implementation of a 1.8-V 5.8-GHz distributed voltage-controlled oscillator module based on bipolar transistors. The oscillator delivered -2-dBm-output power with a current consumption of 11.5 mA. The tuning range achieved was 650 MHz. The measured phase noise was -100 dBc/Hz at 1-MHz offset. The circuit construction was simple and robust and no buffer amplifier was needed. The design can be used for 5.8-GHz ISM band wireless LAN applications.     

High-Q active resonators using amplifiers and their applications to low phase-noise free-running and voltage-controlled oscillators

This paper presents a new technique to design high-Q active resonators. The active resonators are then used in the design of low phase-noise oscillators. The proposed new technique uses an amplifier to generate a negative resistance, which compensates for the resonator losses and increases the Q factor. The active resonator using this technique shows a high loaded Q factor of 548.62 from measurement at the fixed 10-GHz resonant frequency. Considerations to design a voltage tunable active resonator is given and measurements show that the loaded Q factors exceed 500 with a 120-MHz tuning range. A low phase-noise free-running and voltage-controlled oscillator (VCO) were designed as an application of the proposed active resonators. The phase noise of the free-running oscillator using the active resonator is -114.36 dBc/Hz at 100-kHz offset, which is 14 dB lower than the phase noise of the passive resonator oscillator. In the case of a VCO using the active resonator, the phase-noise performance is below -110 dBc/Hz over the whole tuning range, which is lower 13 dB compared to the passive resonator VCO. The total dc power consumptions are approximately 500 mW.     

Effects of losses and parasitics on a voltage-controlled tunable distributed RC notch filter

An evaluation is given on the effects of MIS losses and parasitic notch inductance on the tuning-range compression of a voltage-controlled tunable distributed URC notch filter.     

Silicon-based optoelectronics

The decade of the 1990's is an opportune time for scientists and engineers to create cost-effective silicon “superchips” that merge silicon photonics with advanced silicon electronics on a silicon substrate. We can expect significant electrooptical devices from Column IV materials (Si, Ge, C and Sn) for a host of applications. The best devices will use strained-layer epitaxy, doped heterostructures, and bandgap engineering of quantum-confined structures. This paper reviews Si-based photonic components and optoelectronic integration techniques, both hybrid and monolithic     

Silicon-based micro-Fourier spectrometer

A novel Fourier spectrometer based on a partly transparent thin-film detector in combination with a tunable silicon micromachined mirror was developed. The operation principle based on the detection of an intensity profile of a standing-wave by introducing a partly transparent detector in the standing-wave. Varying the position of the mirror results in a phase shift of the standing-wave and thus in a change of the optical intensity profile within the detector. The photoelectric active region of the sensor is thinner than the wavelength of the incoming light, so that the modulation of the intensity leads to the modulation of the photocurrent. The spectral information of the incoming light can be determined by the Fourier transform of the sensor signal. Based on the linear arrangement of the sensor and the mirror, the spectrometer facilitates the realization of one- and two-dimensional arrays of spectrometers combining spectral and spatial resolution. The operation principle of the spectrometer will be described and the influence of the detector design on the spectrometer performance will be discussed. A spectral resolution of down to 6 nm was achieved under real-time imaging conditions.     

Digital voltage-controlled blocking oscillator

A digital voltage-controlled blocking oscillator is presented, which can generate a number of pulses during a period of blocking oscillation. The number of pulses can be changed due to supply voltage.