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This article comprehensively reviews and studies CMOS transformer tank voltage‐controlled oscillators (VCOs) designed to improve the frequency tuning range (FTR) and minimize phase noise (PN) across a broad frequency range, particularly for mm‐wave and fifth‐generation applications. The study focuses on enhancing the performance of the oscillators to meet the demanding requirements of these advanced applications. This study thoroughly investigates and compares various strategies to increase the FTR, minimize PN, and reduce power dissipation in transformer tank VCOs. The aim is to establish fundamental guidelines for implementing transformer‐based tank VCOs. The study comprehensively reviews and analyzes the overall architecture of transformer‐based tank VCOs, presenting a detailed examination of the methods employed to enhance VCO performance. Additionally, the study illustrates the impact of the coupling factor on the VCO's performance parameters, detailing and demonstrating the overall tank circuit quality factor (Q) and resonator coupling factor (κ). A thorough understanding of PN methodology and the limitations of FTR has led to the development of innovative architectures. These include transformer‐based capacitive feedback (FB) oscillators with resistively adjusted variable inductors, as well as class‐F and inverse class‐F VCOs. These novel architectures contribute significantly to the improvement of oscillator performance. [ABSTRACT FROM AUTHOR]

Summary: This paper presents more compatible three‐stage inverter‐based ring voltage controlled oscillators (VCOs) by modifying the current‐starved delay cell to oscillate with high tuning range. Unlike some ring structures in which extra transistors are used as current boosting to enhance the frequency tuning range, no extra elements are used in the proposed three‐stage VCOs for increasing the tuning range. Besides, a new method is introduced to couple two proposed ring VCOs for designing a six‐phase ring VCO. The coupling method can be generalized to some other ring VCOs to generate multiphase signals. The proposed circuits have wide frequency tuning ranges and show good noise performances. The proposed six‐phase VCO can oscillate from 1.62 GHz to 3.45 GHz, which illustrates 72.2% tuning range. The phase noise of the proposed VCO is −97.5 dBc/Hz at 1 MHz offset frequency. The circuit figure of merit is −181.5 dBc/Hz. The post‐layout simulation results of the proposed six‐phase VCO are provided based on the TSMC 0.18 μm CMOS process. [ABSTRACT FROM AUTHOR]

Here, a new design of a variable micro electromechanical system (MEMS) capacitor is introduced to use in telecommunication systems. For the first time, an on‐chip MEMS component has been used in the substrate integrated waveguide (SIW) structures to avoid discrete and non‐integrated connection problems and high noise levels and affects the operating frequency of telecommunication systems. The behaviour of two capacitors with the fixed–fixed and supported membrane by special spiral arms is analysed and simulated using the finite element method. The MEMS bridges are implemented by a 6 μm gold layer and an air gap of 3 μm. It can be seen that using the new special arms, the movement of the membrane is more uniform than the clamped while the actuation voltage is up to 1.32 V and the tuning range of the capacitor is 29%. Then both the capacitors are placed on half‐mode SIW structure and the electromagnetic simulation is done. Finally, the results comparison shows that the frequency tuning range of the MEMS variable capacitor is more significant than the other. [ABSTRACT FROM AUTHOR]

A quasi‐lumped dual‐mode reconfigurable eight‐way filtering power divider (FPD) is presented. Two operating modes are one eight‐way tunable FPD and one all stopband filter (ASF) with high suppression. The measured eight‐way FPD can be tuned from 1.0 to 2.15 GHz, corresponding to the frequency tuning range (FTR) of 73%. The ASF is obtained by misaligning resonant frequencies of LC resonators and weakening their coupling. The proposed dual‐mode FPD has the advantage of wide FTR, compact size, high isolation, ultra‐wide isolation BW, and high suppression. [ABSTRACT FROM AUTHOR]

ABSTRACT This letter presents CMOS voltage controlled oscillator (VCO) circuit, as a part of Automatic Dependent Surveillance-Broadcast (ADS-B) transmitter, operating at the center frequency of 980 MHz, delivers highest output power with highest efficiency ever reported to the best of authors' knowledge. The 0.713 mm × 0.638 mm VCO chip fabricated using 0.18 μm CMOS technology exhibits the single-ended peak output power of 1.4 dBm and the differential peak output power of 4.4 dBm at the frequency of 1.097 GHz, with the frequency tuning range from 980 MHz to 1.1 GHz, and phase noise of −125 dBc/Hz at 1 MHz offset centered at the frequency of 980 MHz, consuming 48-mW power from 1.8-V supply, thus showing state-of-the-art performances. This promising result shows a path toward realizing high-power single-chip CMOS ADS-B transmitter. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2437-2441, 2015 [ABSTRACT FROM AUTHOR]

In this article, a novel voltage-controlled oscillator (VCO) using the output matching network based on the novel harmonic control circuit is presented for reducing the phase noise without the reduction of the frequency tuning range. The phase noise suppression is achieved by the harmonic control circuit having the short impedances for the second- and third-harmonic components. The high-Q resonator has been used for reducing the phase noise but has the problem that the frequency tuning range has been also reduced by the increase of the Q value of the resonator. However, the frequency tuning range of the proposed VCO has not been reduced because the phase noise has been reduced without the high-Q resonator. The microstrip square open loop multiple split ring resonator has been used with the proposed harmonic control circuit for better phase noise property. The phase noise of this VCO has been -127.5 to -126.33 dBc/Hz @ 100 kHz in the tuning range, 5.744–5.865 GHz. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1838–1842, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24510 [ABSTRACT FROM AUTHOR]

In this article, a K-band push-push Voltage Controlled Oscillator (VCO) is presented using a miniaturized hairpin resonator (MHR) with a higher loaded quality factor and the reduced circuit area within 50% compared to the conventional one at 9.2 GHz.The MHR combined with the GaAs MESFET varactor shows a tuning range of 140 MHz, and this voltage tunable MHR is used to compose a push-push VCO. It provides the frequency tuning range of 71 MHz with flatness of +0.13 dB, which is increased by 31 MHz compared to the conventional VCO. The voltage controlled push-push oscillator based on the series feedback topology is implemented on 0.54 mm-thick Teflon substrate with a dielectric constant of 2.54. The measurement shows the output power of 1.18 dBm, the fundamental signal power suppression of -33 dBc, and phase noise performance of -86.78 dBc/Hz at 100 kHz offset. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52: 699–701, 2010; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/mop.25007 [ABSTRACT FROM AUTHOR]