An inductorless modulator driver with effective overshoot suppression and a large swing for high-speed optical communications is presented. A novel interleave frequency variant feedback (IFVF) ...technique is proposed, which employs active feedback loops with the RC degeneration. The <inline-formula> <tex-math notation="LaTeX">RC</tex-math> </inline-formula> degeneration allows place the pole in the overall transfer function to shape the waveform for overshoot and ringing suppression. Using a 90-nm complementary metal oxide semiconductor (CMOS) technology, the driver achieves a maximum 3.4 V<inline-formula> <tex-math notation="LaTeX">_{\text{pp}}</tex-math> </inline-formula> differential output voltage swing. Clear eye diagrams for non-return to zero (NRZ) and pulse amplitude modulation 4-level (PAM4) signal formats can be obtained up to 32 Gb/s and 20 Gbaud, respectively. The circuit consumes a total power of 560 mW and occupies a core area of only 0.092 mm<inline-formula> <tex-math notation="LaTeX">^{\text{2}}</tex-math> </inline-formula>.
Flexible integrated circuits with complex functionalities are the missing link for the active development of wearable electronic devices. Here, we report a scalable approach to fabricate self-aligned ...graphene microwave transistors for the implementation of flexible low-noise amplifiers and frequency mixers, two fundamental building blocks of a wireless communication receiver. A devised AlO x T-gate structure is used to achieve an appreciable increase of device transconductance and a commensurate reduction of the associated parasitic resistance, thus yielding a remarkable extrinsic cutoff frequency of 32 GHz and a maximum oscillation frequency of 20 GHz; in both cases the operation frequency is an order of magnitude higher than previously reported. The two frequencies work at 22 and 13 GHz even when subjected to a strain of 2.5%. The gigahertz microwave integrated circuits demonstrated here pave the way for applications which require high flexibility and radio frequency operations.
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A 300-MHz class-E dc-dc converter using the resonant gate driving technique is proposed. The gate driver utilizes the harmonic shaping network and RC feedback to enhance the output swing voltage, and ...the class-E power converter can minimize the voltage-current overlap to improve efficiency. With the 0.25-μm GaN high-electron-mobility transistor and 0.18-μm CMOS for the switching power device and the gate driver, respectively, a complete dc-dc converter operating at 300 MHz is demonstrated including all the passive components microfabricated by integrated passive device (IPD) technology on the high-resistivity silicon substrate. The overall chip area is smaller than 1 cm × 1 cm and the volume is only 0.115 cm 3 . The measured results show a maximum output power of 4.16 W with 47.3% efficiency. An excellent power density of 36.2 W/cm 3 can be achieved. The flip-chip assembled converter on the IPD substrate demonstrates the potential of heterogeneous integration for high-frequency power conversion applications.
In this article, a novel duplexing rectenna with harmonic feedback capability is proposed for efficient wireless power transfer (WPT) applications. The proposed duplexing rectenna can harvest the ...incoming radio frequency (RF) energy efficiently and also make use of an inherent harmonic signal, which is sent back to the RF transmitter (Tx) for positioning in order to guide the radiation patterns from Tx antenna array for optimum WPT. A novel duplexing dipole antenna is designed based on the top loading and capacitive gap effects. It is used to receive RF power at fundamental frequency 0.915 GHz and transmit the second harmonic signals at 1.83 GHz as a feedback. Experimental validation of a complete WPT system with beam-scanning capability has been carried out. It is shown that the fabricated rectifier has realized a maximum RF-dc conversion efficiency of 71% (at 15-dBm input power) and a measured peak second harmonic power of −1 dBm. Thus, the proposed duplexing rectenna can form a closed-loop system by providing its location information for efficient WPT applications.
In this letter, we demonstrate high-performance AlGaN/GaN Schottky barrier diodes (SBDs) on Si substrate with a recessed-anode structure for reduced turn-on voltage VON. The impact of the surface ...roughness after the recessed-anode formation on device characteristics is investigated. An improved surface condition can reduce the leakage current and enhance the breakdown voltage simultaneously. A low turn-on voltage of only 0.73 V can be obtained with a 50-nm recess depth. In addition, the different lengths of Schottky extension acting like a field plate are investigated. A high reverse breakdown voltage of 2070 V and a low specific ON-resistance of 3.8 mΩ · cm 2 yield an excellent Baliga's figure of merit of 1127 MW/cm 2 , which can be attributed to the low surface roughness of only 0.6 nm and also a proper Schottky extension of 2 μm to alleviate the peak electric field intensity in the SBDs.
A high-efficiency compact broadband rectifier is developed for wireless energy harvesting. A novel three-stage impedance matching technique is utilized in a broadband rectifier design to achieve high ...conversion efficiency with a compact size. In the rectifier, a low loss impedance matching technique is initiated by employing a linearly tapered transmission line for controlling the impedance curve at the required input power level, followed by two stages to make a circular impedance curve for wideband impedance matching. Both theoretical analysis and numerical simulations of the proposed rectifier are performed. For validation, a prototype is fabricated and demonstrated a broadband performance with a fractional bandwidth (FBW) of 74% (from 1.12 to 2.43 GHz) and power conversion efficiency of more than 50% at a 5 dBm input power level. Moreover, the rectifier can reach an efficiency of more than 50% extending from 0.97 to 2.55 GHz (FBW = 90%) at the input power of 10 dBm, which is the highest bandwidth reported under this condition. This low complexity design is suitable for realizing broadband rectifiers for wireless energy harvesting (WEH) applications.
This article presents two ultracompact inductorless low-noise amplifiers (LNAs) in 40-nm CMOS for cryogenic qubit readout. Both LNAs utilize an inverter-based input stage as the main amplifier, and ...LNA-I and LNA-II employ a complementary and common-source (CS) stage, respectively, as the auxiliary amplifier for achieving noise canceling (NC). LNA-I also incorporates self-forward body bias (SFBB) to counter <inline-formula> <tex-math notation="LaTeX">{V} _{\text {th}} </tex-math></inline-formula> reduction and improve <inline-formula> <tex-math notation="LaTeX">{r} _{\text {out}} </tex-math></inline-formula> during cryogenic operation, while LNA-II uses source-follower feedback(SFFB) to enhance gain and noise figures (NFs) without compromising input impedance matching. At room temperature (RT), LNA-I achieves a measured gain (<inline-formula> <tex-math notation="LaTeX">{S} _{21} </tex-math></inline-formula>) of 25.6 dB and a minimum NF of 0.63 dB at 2 GHz. At 4 K, it demonstrates a measured gain of 29 dB and a minimum NF of 0.033 dB (corresponding to a noise temperature <inline-formula> <tex-math notation="LaTeX">{T} _{N} </tex-math></inline-formula> of 2.2 K), along with a 3-dB bandwidth <inline-formula> <tex-math notation="LaTeX">{f} _{\text {3 dB}} </tex-math></inline-formula> from 10 MHz to 3 GHz, while consuming 19.4 mW. LNA-II achieves a measured gain of 27 dB and a minimum NF of 1.16 dB at 0.5 GHz at RT. At 4 K, it demonstrates a measured gain of 30.2 dB and a minimum NF of 0.29 dB (<inline-formula> <tex-math notation="LaTeX">{T} _{N} </tex-math></inline-formula> of 20 K), accompanied by a <inline-formula> <tex-math notation="LaTeX">{f} _{\text {3 dB}} </tex-math></inline-formula> from 20 MHz to 4 GHz and with a total power consumption of 10.8 mW. The circuit only occupies an active area of 0.018 and 0.0072 mm2 for LNA-I and LNA-II, respectively.
High-quality graphene grown on metal-free substrates represents a vital milestone that provides an atomic clean interface and a complementary metal-oxide-semiconductor-compatible manufacturing ...process for electronic applications. We report a scalable approach to fabricate radio frequency field-effect transistors with a graphene channel grown directly on the sapphire substrate using the technique of remote-catalyzed chemical vapor deposition (CVD). A mushroom-shaped AlO x top gate is used to allow the self-aligned drain/source contacts, yielding remarkable increase of device transconductance and reduction of the associated parasitic resistance. The quality of thus-grown graphene is reflected in the high extrinsic cutoff frequency and maximum oscillation frequency of 10.1 and 5.6 GHz for the graphene channel of length 200 nm and width 80 μm, respectively, potentially comparable with those of transferred CVD graphene at the same channel length and holding promise for applications in high-speed wireless communications.
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This paper presents CMOS distributed amplifiers (DAs) using the proposed gate-drain transformer feedback technique. The feedback allows reuse of the traveling signal to achieve a high gain-bandwidth ...product while maintaining low power consumption of DAs. With the folded transmission lines and patterned ground shield, the miniaturized transformer has high quality factors and a well-controlled feedback coupling coefficient. Two DAs are realized using the proposed technique in both 0.18-μm and 90-nm CMOS technologies, respectively. The 0.18-μm CMOS DA achieves a gain of 9.5 dB with a 3-dB bandwidth of 32 GHz, and the noise figure (NF) ranges from 4.1 to 7.6 dB under a power consumption of 71 mW. Under a power consumption of 60 mW, the 90-nm DA demonstrates a gain of 7 dB, a bandwidth of 61.3 GHz, and an NF below 6.2 dB up to 40 GHz. The core areas of the 0.18-μm and 90-nm designs are only 0.58 and 0.41 mm 2 , respectively.
An ultra-low-power 60 GHz low-noise amplifier (LNA) with a 12.5 dB peak gain and a 5.4 dB minimum NF is demonstrated in a 90 nm CMOS technology. The LNA is composed of four cascaded common-source ...stages with the gate-source transformer feedback applied to the input stage for simultaneous noise and input matching. Also, the drain-source transformer feedback is used in the following stages for gain enhancement and interstage/output matching. This LNA consumes only 4.4 mW from a 1 V supply with a compact core area of 0.047 .
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