More Like this

1. A Low Phase Noise 28 GHz VCO Using Transformer-based Q-enhanced Active Impedance Converter

   https://doi.org/10.1109/IMS37962.2022.9865389  

   Hoque, Md Aminul ; Chahadori, Mohammad ; Mokri, Mohammad Ali ; Mohapatra ; Soumen Mohapatra ; Kar, Dipan ; Heo, Deukhyoun ( July 2022 , IEEE International Microwave Symposium)

   This paper presents a low phase noise 28 GHz voltage-controlled oscillator (VCO) using a transformer-based active impedance converter to enhance the quality factor (Q) of the capacitor in the resonator. The active impedance converter can enhance the Q of a capacitor bank and varactor by 25-40% across the VCO’s tuning range. The proposed VCO is fabricated using the proposed transformer-based Q-enhancement impedance converter in a standard 65 nm CMOS process. The VCO achieves a 15.9% measured fractional frequency tuning range and phase noise of −107.6 dBc/Hz at 1 MHz offset from 28 GHz oscillation frequency while occupying only 0.05 mm2 area (200 μm × 250 μm). The VCO consumes 5.1 mW power, resulting in an excellent figure-of-merit (FoM) of 189.4 dBc/Hz and a figure-of-merit-with-area (FoMA) of 202.8 dBc/Hz. 

   more » « less
2. A Triple-Band, High DC-to-RF Efficiency, Multicore VCO With a Dual-Path Inductor and Mode-Switching Capacitor

   https://doi.org/10.1109/TMTT.2024.3439653  

   Hoque, Md Aminul ; Heo, Deukhyoun ( January 2024 , IEEE Transactions on Microwave Theory and Techniques)

   This article introduces an innovative four-port dual-path inductor designed to deliver two distinct inductance values to the resonator of a voltage-controlled oscillator (VCO). The switching between the inductor’s two excitation modes, even and odd, is determined by the differential excitation’s input polarity, eliminating the need for a series switch. Thus, the inductor has a high-quality factor ( Q ) in both modes. The inductances in these modes can be independently set based on desired frequencies. This inductance change achieves coarse frequency tuning, while fine-tuning is realized by a conventional 2-bit capacitor bank with a small-size varactor. This inductor is well suited for designing multiband VCOs aimed at widely spaced operation frequency bands. Apart from the inductance change, a particular case of mode-switching capacitor is employed to extend to another frequency band in between the low and middle bands, achieving triple-band oscillation. As a result, this article presents two VCOs designed using the proposed inductor: one in class-D biasing in a 65-nm CMOS process and another with class-B biasing in a 180-nm BiCMOS process. Both VCOs successfully oscillate across three distinct frequency bands, centered at 19, 28, and 36 GHz, while maintaining outstanding phase noise and minimal power consumption. Measurement results show good match with simulation, resulting in a peak figure of merit (FoM) of 185.7 dBc/Hz at 18.5 GHz, and occupy 0.088- mm2 (250 × 350 μ m) area in both processes. 

   more » « less
3. A Single-Switch 3.1-4.7 GHz 194.52-dB FoM Class-D VCO With 495μW Power Consumption

   https://doi.org/10.1109/TCSII.2024.3407842  

   Liu, Xuyang ; Moradi, Behnam ; Aghasi, Hamidreza ( January 2024 , IEEE Transactions on Circuits and Systems II: Express Briefs)

   Bonizzoni, Edoardo (Ed.)

   This brief presents an ultra-low-power class-D voltage-controlled oscillator (VCO) designed for GHz applications that mandate decent phase noise performance. A waveform-centric approach of phase noise reduction by controlling the ratio between the floating and single-ended (SE) capacitors in an oscillator tank is proposed. By co-designing an RF choke with the tank inductor to introduce high impedance for the floating capacitors, the optimum capacitance ratio is maintained across the tuning range. The VCO is fabricated in 65nm Bulk CMOS technology and achieves a measured phase noise of -118.36 dBc/Hz and -138.64 dBc/Hz, and figure-of-merit of 192.89 dBc/Hz and 194.52 dBc/Hz at 1 MHz and 10 MHz offset frequencies, respectively. The VCO’s lowest measured 1/f3 corner is approximately 50kHz, which enables a decent figure-of-merit (FoM) down to a frequency offset of 10 kHz. The VCO features a tuning range of 40% (3.1 GHz -4.66 GHz) using a one-bit switch to realize two-point modulation in phase-locked loops (PLLs) with milliwatt-level power consumption. 

   more » « less
4. A 23.7 to 29.9 GHz Tunable Fully Differential Voltage Controlled Oscillator Designed in 180nm CMOS process

   https://doi.org/10.1109/DCAS57389.2023.10130248  

   Kakaraparty, Karthik ; Mahbub, Ifana ( April 2023 , 2023 IEEE 16th Dallas Circuits and Systems Conference (DCAS))

   This paper presents the design of a 23.7 to 29.9 GHz wide tuning range VCO (Voltage Controlled Oscillator) designed using a 180 nm CMOS process. In order to achieve a good phase noise performance and get a wide frequency tuning range, cross-coupling and gate biasing techniques are utilized in the proposed cross-coupled LC VCO architecture. The simulated phase noise of −130 dBc/Hz is achieved at a 1 MHz offset. With the supply voltage of 1.8 V, the total power consumption of the VCO is 32.04 mW. The proposed VCO has good performance in terms of low-phase noise and has a wide frequency tuning range, which makes it highly suitable for millimeter wave-based applications. 

   more » « less
5. A 300-500 MHz Tunable Oscillator Exploiting Ten Overtones in Single Lithium Niobate Resonator

   Kourani, Ali ; Lu, Ruochen ; Gao, Anming ; Gong, Songbin ( May 2019 , 2019 IEEE International Frequency Control Symposium)

   This paper presents the first voltage-controlled MEMS oscillator (VCMO) based on a Lithium Niobate (LiNbO3) lateral overtone bulk acoustic resonator (LOBAR). The VCMO consists of a LOBAR in a closed loop with 2 amplification stages and a varactor-embedded tunable LC tank. By adjusting the bias voltage applied to the varactor, the tank can be tuned to change the closed-loop gain and phase responses of the oscillator so that the Barkhausen conditions are satisfied for a particular resonance mode. The tank is designed to allow the proposed VCMO to lock to any of the ten overtones ranging from 300 to 500 MHz. Owing to the high-quality factors of the LiNbO3 LOBAR, the measured VCMO shows a low close-in phase noise of -100 dBc/Hz at 1 kHz offset from a 300 MHz carrier and a noise floor of -153 dBc/Hz while consuming 9 mW. With further optimization, this VCMO can lead to direct radio frequency (RF) synthesis for ultra-low power transceivers in multi-mode Internet-of-Things (IoT) nodes. 

   more » « less