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

Hemmati, Mohammad Jafar; Naseh, Sasan

doi:10.1007/s10470-011-9645-2

Cited by 5 publications

(4 citation statements)

References 18 publications

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“…As reported in the studies conducted by Ebrahimi and Naseh (2011) and Hemmati and Naseh (2011), low robustness is the main issue of these structures. In other words, the presented circuits in the studies conducted by Naseh et al (2008), Soltanian and Kinget (2006) and Hemmati and Naseh (2011) are in quadrature only for a narrow region of the circuit parameters, and there are no clear design guides to find this region. It is worth mentioning, the proposed QVCOs in the studies conducted by Ebrahimi and Naseh (2011); Gierkink et al (2003); Hancock and Rebeiz (2004); Kuo et al (2015) and Jafari and Sheikhaei (2018a) have a good robustness because of enforcing 180°phase shift by coupling elements or mechanism.…”

Section: Introductionmentioning

confidence: 80%

“…X 1 ) has been introduced as a common-mode node for coupling. As reported in studies conducted by Ebrahimi and Naseh (2011) and Hemmati and Naseh (2011), the presented LC-QVCOs in Naseh et al (2008) and Soltanian and Kinget (2006), which are made by a direct connection of two identical common-mode nodes, suffer from low robustness.…”

Section: Proposed Switching Superharmonic Coupling Schemementioning

confidence: 98%

“…Another group of superharmonic QVCOs is based on direct coupling of common-mode nodes. In studies conducted by Naseh et al (2008); Soltanian and Kinget (2006) and Hemmati and Naseh (2011), identical common-mode nodes of two core LC-VCOs are directly connected together and the circuit parameters are chosen in such a way that the circuits operate in quadrature. As reported in the studies conducted by Ebrahimi and Naseh (2011) and Hemmati and Naseh (2011), low robustness is the main issue of these structures.…”

Section: Introductionmentioning

confidence: 99%

“…In studies conducted by Naseh et al (2008); Soltanian and Kinget (2006) and Hemmati and Naseh (2011), identical common-mode nodes of two core LC-VCOs are directly connected together and the circuit parameters are chosen in such a way that the circuits operate in quadrature. As reported in the studies conducted by Ebrahimi and Naseh (2011) and Hemmati and Naseh (2011), low robustness is the main issue of these structures. In other words, the presented circuits in the studies conducted by Naseh et al (2008), Soltanian and Kinget (2006) and Hemmati and Naseh (2011) are in quadrature only for a narrow region of the circuit parameters, and there are no clear design guides to find this region.…”

Section: Introductionmentioning

confidence: 99%

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A new tail-switching superharmonic multiphase LC-VCO

Ebrahimi

2020

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Purpose Multiphase and quadrature voltage-controlled oscillators (QVCOs) play key roles in modern communication systems and their phase noise performance affects the performance of the overall system. Different studies are devoted to efficient quadrature signals generation. This paper aims to present a new low-phase noise superharmonic injection-locked QVCO. Design/methodology/approach The proposed QVCO is comprised of two identical inductor-capacitor circuit (LC)-voltage-controlled oscillators (VCOs) in which second harmonics, with 180° phase shift, are injected from one core VCO to the gate of tail current source of the other VCO via a coupling capacitor. Using second harmonics with high amplitude will switch the tail from the inversion to the accumulation, and therefore, flicker noise is reduced. Also, because of the use of lossless and noiseless coupling elements, that is, coupling capacitors, and also because of the existence of an inherent high-pass filter, the proposed LC-QVCO has a good phase noise performance. Findings The introduced technique is designed and simulated in a commercial 0.18 µm radio frequency complementary metal oxide semiconductor (RF-CMOS) technology and 10 dB improvement of close-in phase noise is achieved (compared to the conventional method). Simulation results show that the phase noise of the proposed QVCO is −130.3 dBc/Hz at 3 MHz offset from 5.76 GHz center frequency, while the total direct current (DC) current drawn from a 0.9-V power supply is 4.25 mA (figure of merit = −190.2 dBc). Monte Carlo simulation results show that the figure of merit of the circuit has a Gaussian distribution with mean value and standard deviation of −189.97 dBc and 0.183, respectively. Originality/value This technique provides a new simple but efficient superharmonic coupling and noise shaping method that reduces close-in phase noise of superharmonic multiphase VCOs by switching of tail transistors with 2 ω0 (second harmonic of oscillation frequency). No extra devices such as area-consuming transformer or additional power-hungry oscillator are used for coupling.

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Section: Introductionmentioning

confidence: 80%

Section: Proposed Switching Superharmonic Coupling Schemementioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A new tail-switching superharmonic multiphase LC-VCO

Ebrahimi

2020

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Wide Frequency Multiphase Oscillator Designed by Coupling Two Identical Ring Voltage Controlled Oscillators

Hemmati,

Mood,

Dehnavi

2024

Circuit Theory & Apps

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This work presents a novel wide tuning range ring voltage controlled oscillator (RVCO) designed to generate six‐phase signals. The proposed circuit is realized by coupling two identical three‐stage single‐ended inverter‐based RVCOs. The coupling network injects the common mode signals from one RVCO to the other one and vice versa in a cross‐connected manner. Three‐stage RVCOs used for coupling have been configured by modifying the conventional current‐starved RVCO. The proposed six‐phase RVCO is optimized using an improved version of non‐dominated Sorting Genetic Algorithm III (NSGAIII). In this algorithm, the sigma scaling method is used to control selection pressure and enhance the algorithm's performance. The proposed RVCO oscillates at 3.46 GHz. It can operate from 970 MHz to 4 GHz with a supply voltage of 1.5 V, demonstrating a wide frequency tuning range of 120%. Additionally, another six‐phase oscillator is proposed, achieved by capacitively coupling two identical three‐stage RVCOs. Both proposed oscillators are designed in TSMC 0.18 μm CMOS technology.

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