Quadrature LC VCO with passive coupling and phase combining network

A circuit and method for generating a signal is disclosed. The circuit includes a set of wide tuning LC tanks, a set of core transistors cross coupled to the set of wide tuning LC tanks, and a combining network coupled to the set of wide tuning LC tanks and the set of core transistors. The combining network further includes a set of inputs connected to the set of wide tuning LC tanks and the set of core transistors, a set of coupling transistors connected to the set of inputs, a set of source inductors connected to the set of coupling transistors, a coupling capacitor connected to the set of source inductors, a load resistor connected to the coupling capacitor. The combining network combines the set of inputs and the signal is delivered to the load resistor as a fourth order harmonic.Board of Regents, University of Texas Syste

Concepts and methods in optimization of integrated LC VCOs

Underlying physical mechanisms controlling the noise properties of oscillators are studied. This treatment shows the importance of inductance selection for oscillator noise optimization. A design strategy centered around an inductance selection scheme is executed using a practical graphical optimization method to optimize phase noise subject to design constraints such as power dissipation, tank amplitude, tuning range, startup condition, and diameters of spiral inductors. The optimization technique is demonstrated through a design example, leading to a 2.4-GHz fully integrated, LC voltage-controlled oscillator (VCO) implemented using 0.35-μm MOS transistors. The measured phase-noise values are -121, -117, and -115 dBc/Hz at 600-kHz offset from 1.91, 2.03, and 2.60-GHz carriers, respectively. The VCO dissipates 4 mA from a 2.5-V supply voltage. The inversion mode MOSCAP tuning is used to achieve 26% of tuning range. Two figures of merit for performance comparison of various oscillators are introduced and used to compare this work to previously reported results

ACTIVE INDUCTOR BASED LOW PHASE NOISE VOLTAGE CONTROLLED OSCILLATOR

This paper proposed a fully MOS-based voltage-controlled oscillator (VCO) with tuning range and low phase noise, replacing the most often used NMOS-based inductor-capacitor tank arranged in cross-coupled topology with a high-Q active inductor. This study mainly focuses on VCO design using a MOS-based active inductor and is implemented and verified using UMC 180nm CMOS technology. The proposed VCO is resistorless and consists of an active inductor, two MOS capacitors, and the buffer circuits. The fundamental principle of this MOS-based VCO concept is to use MOS based inductor to replace the passive inductor, which is an active inductor that gives less area and low power usage. At 1 MHz frequency offset, the phase noise achieved by this proposed configuration is -102.78dBc/Hz. In the proposed VCO architecture, the frequency tuning range is 0.5GHz to 1.7GHz. This VCO design can accomplish this acceptable tuning range by altering the regulating voltage from 0.7V to 1.8V. This suggested architecture of proposed VCO design has the power consumption of 9mW with a 1.8V supply voltage. The suggested VCO has been shown to be a good fit for low-power RF circuit applications while preserving acceptable performance metrics

Analysis and design of a 195.6 dBc/Hz peak FoM P-N class-B oscillator with transformer-based tail filtering

A complementary p-n class-B oscillator with two magnetically coupled second harmonic tail resonators is presented and compared to an N-only reference one. An in depth analysis of phase noise, based on direct derivation of the Impulse Sensitivity Function (ISF), provides design insights on the optimization of the tail resonators. In principle the complementary p-n oscillator has the same optimum Figure of Merit (FoM) of the N-only at half the voltage swing. At a supply voltage of 1.5 V, the maximum allowed oscillation amplitude of the N-only is constrained, by reliability considerations, to be smaller than the value that corresponds to the optimum FoM even when 1.8 V thick oxide transistors are used. For an oscillation amplitude that ensures reliable operation and the same tank, the p-n oscillator achieves a FoM 2 to 3 dB better than the N, only depending on the safety margin taken in the design. After frequency division by 2, the p-n oscillator has a measured phase noise that ranges from -150.8 to -151.5 dBc/Hz at 10 MHz offset from the carrier when the frequency of oscillation is varied from 7.35 to 8.4 GHz. With a power consumption of 6.3 mW, a peak FoM of 195.6 dBc/Hz is achieved.This work was supported by the European Marie Curie IAPP Grant Agreement N 251399.info:eu-repo/semantics/publishedVersio

Analysis and Design of a 1.8-GHz CMOS LC Quadrature VCO

This paper presents a quadrature voltage-controlled oscillator (QVCO) based on the coupling of two LC-tank VCOs. A simplified theoretical analysis for the oscillation frequency and phase noise displayed by the QVCO in the 1/f/sup 3/ region is developed, and good agreement is found between theory and simulation results. A prototype for the QVCO was implemented in a 0.35-/spl mu/m CMOS process with three standard metal layers. The QVCO could be tuned between 1.64 and 1.97 GHz, and showed a phase noise of -140 dBc/Hz or less across the tuning range at a 3-MHz offset frequency from the carrier, for a current consumption of 25 mA from a 2-V power supply. The equivalent phase error between I and Q signals was at most 0.25/spl deg/