Phase noise optimization of CMOS VCO through harmonic tuning

A design of a 5.6 GHz frequency synthesizer with switched bias LIT VCO and low noise on‐chip LDO regulator for 5G applications

This paper presents a wide-range and low phase noise mm-Wave Voltage Controlled Oscillator (VCO) based on the transconductance linearization technique. The proposed technique eliminates the deep triode region of the active part of the VCO, and lowers the noise introduced by the gm-cell. The switch sizes inside the switched capacitor bank of the VCO are optimized to minimize the resistance of the switches while keeping the wide tuning range. A new layout technique shortens the routing of the VCO outputs, and lowers the parasitic inductance and resistance of the VCO routing. The presented method prevents the reduction of the quality factor of the tank due to the long routing. The proposed VCO achieves a discrete frequency tuning range, of 14 GHz to 18 GHz, through a linear coarse and middle switched capacitor array, and offers superior phase noise performance compared to recent state-of-the-art VCO architectures. The design is implemented in a 45 nm CMOS process and occupies a layout area (including output buffers) of 0.14 mm2. The power consumption of the VCO core is 24 mW from the power supply of 0.8 V. The post-layout simulation result shows the VCO achieves the phase noise performances of −87.2 dBc/Hz and −113 dBc/Hz, at 100 kHz and 1 MHz offset frequencies from the carrier frequency of 14 GHz, respectively. In an 18 GHz carrier frequency, the results are −87.4 dBc/Hz and −110 dBc/Hz, accordingly.

In this paper, a 24GHz frequency source for low phase noise is presented in a 0.18µm CMOS process. The 24GHz frequency source chip is composed of a 12GHz voltage controlled oscillator (VCO) and a 24GHz balanced frequency doubler with class B gate bias. Compared to a conventional complementary VCO, the proposed 12GHz VCO has phase noise improvement by using resistor current sources and substituting the nMOS cross-coupled pair in the conventional complementary VCO for a gm-boosted nMOS differential Colpitts pair. The measured phase noise and fundamental frequency suppression are -107.17dBc/Hz at a 1MHz offset frequency and -20.95dB at 23.19GHz frequency, respectively. The measured frequency tuning range is from 23.19GHz to 24.76GHz drawing 2.72mA at a supply voltage of 1.8V not including an output buffer.

Internet of things is a topic of rising interest and intensive research, where power consumption is one of its most relevant challenges. This article presents a new radiofrequency subthreshold ultra low power LC voltage controlled oscillator (VCO). A graphical inductor optimization approach has been proposed and used to design the LC VCO leading to high performances in terms of power consumption, chip area and phase noise. It uses the adaptive body biasing technique to ensure high immunity to process, voltage and temperature variations. Realized in a 130 nm CMOS technology, the VCO occupies a total area of 0.234 mm2. The measured frequency varies between 2.34 and 2.43 GHz. The post-layout simulation results show a phase noise of −116.1 dBc/Hz @1 MHz offset frequency, while the measured phase noise is −107.36 @1 MHz due to noisy measuring environment. The presented VCO provides a measured power consumption of only 168 μW from 0.6 V supply voltage, making it suitable for ultra low power applications.

This study presents an ultra-low-power, low-phase noise, and small-size voltage-controlled ring oscillator for use in implantable electronics operating in the Medical Implant Communication Service (MICS) frequency band and 65-nm IBM CMOS technology. This five-stage voltage-controlled ring oscillator does not require external inductor and capacitor similar to other LC oscillators, and hence, requires very small die area. A new methodology to design them has been employed in this study, and for optimizing the design of this voltage-controlled oscillator (VCO), the phase noise and power consumption of five-stage ring oscillators have been formulated and simulated for different sizes of transistors. The simulated phase noise of this VCO was -111 dBc/Hz at 1 MHz offset from a 400-MHz center frequency. The power consumption of VCO was 158 μW. This VCO has a tuning range from 352 to 454 MHz for tuning within the MICS band frequency, and frequency correction accounts for process supply voltage and temperature effects.

A new design for an ultra-low power, low phase noise differential 10 GHz LC voltage-controlled oscillator (VCO) which is biased in the subthreshold regime, is presented in the 0.18 μm CMOS process, for the first time. The designed circuit topology is an NMOS only cross-coupled LC-tank VCO which has an extra symmetric centre tapped inductor between the source ends of the cross-coupled transistors. Using this inductor leads to an improvement of the phase noise of VCO about 3.5 dB. At the supply voltage of 0.46 V, the output phase noise is －107.8 dBc/Hz at 1 MHz offset frequency from the carrier frequency of 10.53 GHz, so that the dc power consumption is only 0.346 mW. Tuning range is between 10.53 GHz to 11.35 GHz which is 7.5% and the figure of merit is －193.8 dB, which this result shows that this is the first VCO design in the subthreshold regime at this frequency. This VCO can be used for multi-standard wireless LAN communication protocols 802.11a/b/g easily by a frequency division of 2 or 4 respectively.

This paper presents a novel low power consumption, low phase noise, and high tuning range CMOS cross-coupled voltage-controlled oscillator (VCO). Using common mode double-pseudo-resistance technique in the proposed circuit leads to low power dissipation without degrading the phase noise. Additionally, band-switching capacitor array is employed in order to increase the tuning range. The schematic circuit of the proposed VCO is simulated in 0.18 μm 1P6M CMOS process and simulation results show high efficiency of the proposed circuit. The overall tuning frequency range is from 1.7 GHz to 3.18 GHz (59%) with tuning voltage variation range from 0 V to 1.5 V. The proposed VCO circuit has phase noise of -102.6 and -124.3 dBc/Hz at 100 KHz and 1 MHz offset frequency from the carrier, respectively, while consumes 1.98 mW power at 1.5 V supply voltage.

In this paper, a novel voltage controlled oscillator (VCO) with low phase noise, low power consumption and wide tuning range in the industrial, scientific and medical (ISM) band is proposed for communication systems applications. For improving the phase noise, filtering technique is used and VCO is designed with TSMC CMOS 0.18 μm technology and the power supply is 1.5 V. The simulation results with advanced design system (ADS) shows that phase noise in 1 MHz offset frequency from the carrier is -122 dBc/Hz and tuning range is 2 to 2.8 GHz. The power consumption of the core is 2.49 mW.

An 18 GHz coplanar waveguide (CPW) monolithic voltage controlled oscillator (VCO) has been demonstrated using InAlAs/InGaAs HBT technology. The VCO achieves 6% frequency tuning range using a varactor diode constructed from the HBT base-emitter junction. A CPW design was employed to increase the Q-factor of the monolithic resonator as well as reduce the chip size. The VCO obtains an output power of +10/spl plusmn/0.5 dBm over the tuning range and a collector efficiency of 11.5%. A SSB phase noise of -72 and -96 dBc/Hz at 100 kHz and 1 MHz offset frequency from the carrier were achieved, respectively. This represents the first reported phase noise results of an InAlAs/InGaAs-based HBT VCO with a monolithic integrated varactor and are comparable to other MMIC HBT varactor-tuned VCO's reported in this frequency band.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

With the increasing number of mobile communication standards, a large research effort is put into the task of complete integration of RF voltage-controlled oscillators (VCOs) for multi-band and multi-mode direct conversion transceivers. However, RF VCOs are, at present, not fully integrated in transceivers, since they suffer from poor phase noise and fabrication tolerances. Satisfying the phase noise requirements of GSM, IS-136, or UMTS is a major challenge for fully-integrated VCOs. Traditionally, (integrated) RF VCOs are realized with bipolar devices due to their low high-frequency noise and low flicker noise corner frequency. Recently, several publications on CMOS VCOs have appeared, reporting excellent phase noise performance at large frequency offsets. These VCOs, however, suffer from degraded close-to-carrier phase noise due to the high flicker noise of the CMOS devices, and from a low-resistive substrate allowing only low-Q spiral inductors and resulting in higher power consumption. Furthermore, many of the VCOs have nonlinear tuning characteristics because of the abrupt C-V curve of the MOS diode. This wideband BiCMOS VCO for multimode direct conversion transceivers achieves low phase noise both close to the carrier and at large frequency offsets. In addition the VCO must have a wide but sufficiently linear tuning characteristic and low pushing sensitivity. The design must provide sufficient performance margin for production tolerances.

A wideband CMOS LC voltage controlled oscillator (VCO) with small VCO gain (K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">VCO</sub> ) and band step variation was developed. In order to get small K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">VCO</sub> and step variation across different sub-bands, 8-unit capacitor array was optimized and an additional array of varactors was introduced into the LC-tank, both of which are temperature weighted. Implemented in a 65 nm CMOS RF technology, post-layout simulation shows that the proposed VCO can be tuned from 681 MHz to1656 MHz. VCO gain is around 170 MHz/V with 17% variation across the tuning range, while the step between two sub-bands is 99 MHz. Under a 1.2 V supply, the VCO exhibits phase noise of -73dBc/Hz at 10 kHz offset and phase noise -124.3 dBc/Hz at 1 MHz offset from the carrier. VCO figure-of-merit (FoM) of -184.0dBc/Hz is achieved.

A frequency-tuning negative-conductance (-G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> ) boosted structure and applications for a voltage-controlled oscillator (VCO) is presented in this paper. Analog tuning varactors connected to a -G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> boosted structure is proposed to significantly alleviate the limitation of the tuning range for the -G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</sub> boosted structure, resulting in a low-voltage low-power wide-tuning-range VCO. Based on the proposed architecture, the fabricated 0.18-μm CMOS VCO exhibits a measured 49.8% tuning range. Operating at 0.65 V low supply voltage, the VCO core consumes 2.37-mW dc power. At this bias condition, the measured average value of phase noise for all frequency ranges is -115.1 dBc/Hz at 1-MHz offset from the carriers. Relative to recently published wide-tuning-range CMOS VCOs, the proposed VCO simultaneously achieves low supply voltage, low dc power dissipation, low phase noise, and a wide tuning range, leading to a good figure-of-merit (FOM) and FOM including the tuning range. Furthermore, formulas of analysis for the proposed frequency-tuning -Gm boosted structure and wide VCO tuning range are presented, and the mechanisms are validated by experiments.

In this paper, a novel Colpitts voltage-controlled oscillator (VCO) with low phase noise and an octave frequency tuning range is presented. To achieve low phase noise and a wide tuning range concurrently, the designed VCO employs quad-core-coupled structures, series resonators, dual-mode-coupled inductors, and push–push structures. The quad-core-coupled structures are used for phase noise improvement. The presented series resonators effectively expand the tuning range while reducing phase noise deterioration from amplitude-to-phase modulation (AM/PM) conversion. The dual-mode operation based on coupled inductors and quad-core structures further expands the tuning range. In addition, the adopted push–push structure increases the output frequency. Designed in a 180 nm SiGe BiCMOS process, the proposed Colpitts VCO operates from 7.2 to 14.5 GHz with an octave tuning range of 67.3%. The phase noise ranges from −131.4 to −121.8 dBc/Hz with a peak figure-of-merit (FoM) of 183.0 dBc/Hz and figure-of-merit-tuning (FoMT) of 199.5 dBc/Hz at a 1 MHz offset. The proposed VCO exhibits superior performance in phase noise and tuning range and achieves an octave tuning range for the first time in Colpitts VCOs.

In this paper, a fully integrated 5GHz voltage controlled oscillator (VCO) is presented. The VCO is designed with 0.18µm silicon complementary metal oxide semiconductor (Si-CMOS) process. To achieve low phase noise, a novel varactors pair circuit is proposed to cancel effects of capacitance fluctuation that makes harmonic currents which increase phase noise of VCO. The VCO with the proposed varactor circuit has tuning range from 5.1GHz to 6.1GHz (relative value of 17.9%) and phase noise of lower than −110.8dBc/Hz at 1MHz offset over the full tuning range. Figure-of-merit-with-tuning-range (FOMT) of the proposed VCO is −182dBc/Hz.

To design a multi standard and a multi band transceiver, a quadrature voltage controlled oscillator (VCO), which has a wide tuning range, is essential, while providing low phase noise with low current consumption. In this paper, a dual band quadrature VCO in 0.18 mum CMOS process is presented. To accomplish dual band operation, reconfigurable LC tank is adopted. Series coupling transistors are attached to generate quadrature phase signal with low power consumption and low phase noise. To improve phase noise performance, current sources are eliminated and a filter inductor at the common source node is added. The measured phase noises of low frequency mode and high frequency mode are -101.81 dBc/Hz and -100.59 dBc/Hz at 10 kHz offset frequency; and -123.83 dBc/Hz and -115.06 dBc/Hz at 1 MHz offset frequency and figure of merit (FoM) at 1 MHz offset frequency of -181.8 dB and -180.5 dB with 4 mA current consumption with a 1.7 V supply.