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Polymethyl methacrylate (PMMA) is a widely used polymer in applications such as engineering structural plastics, energy storage materials, and biomaterials. However, its poor surface properties lead to fracture and deformation. Functionalization of the PMMA surface can make it more resistant to aggressive environments and prevent it from biodegradation, discoloration, and increased surface roughness. Here, atomic layer deposition (ALD) was used to deposit TiO2 thin films from tetrakis(dimethylamido)titanium (TDMAT) and ozone on PMMA substrates to improve its surface properties without the need for plasma assistance or another interlayer. Spectroscopic ellipsometry was used for the first time to measure the metal oxide film thickness on thick PMMA substrates. Two different growth regimes were observed, one for initial and the other for later ALD cycles. Initially, the growth rate on PMMA was 1.39 A/cycle, which is ~ 3.5 times higher than that on stand-alone silicon (0.4 A/cycle); this is attributed to cyclic chemical vapor deposition of TDMAT and moisture within PMMA concomitant with TiO2 ALD from TDMAT and ozone. However, after the formation of ~ 30-nm-thick film on PMMA, the TiO2 growth rate became similar to that on silicon. Moreover, our results revealed that the presence of PMMA in the deposition reactor affects the TiO2 growth rate on silicon substrates as well. These findings are discussed and corroborated with residual gas analyzer and X-ray absorption near-edge structure data. The thermal stability of the PMMA samples was examined by thermogravimetric analysis. Chemical composition and surface roughness of coated PMMA were studied by X-ray photoelectron spectroscopy and optical profilometry, respectively. The TiO2 coating increased wettability by ~ 70% and surface hardness by 60%.

Atomic Layer Deposition (ALD) is a promising technique to precisely deposit nanometer-thick films on inorganic and organic substrates. ALD is known for the deposition of uniform, conformal, and pinhole-free thin films with a controllable thickness with sequential and self-limiting gaseous reactions on the substrate surface of interest. ALD thin films have a wide range of applications, from semiconductor industries to medical devices. In many studies, ALD thin films are used to modify the biomaterial surface properties for particular biomedical applications. Here, polymethyl methacrylate, titanium-based alloys, and collagen were chosen as substrates for this review; thanks to their biocompatibility, these substrates have several applications in the dental, medical, and biomedical fields. The ALD of Titanium (IV) oxide (TiO2) films has been selected for this review as a biocompatible material which has attracted increasing attention in biomedical applications. Selected publications focusing on the modification of the surface of these biomaterials with TiO2 ALD are discussed.

Titanium(IV) oxide (TiO2) and zirconium(IV) oxide (ZrO2) are well-known materials for their biocompatibility, hydrophilicity, antimicrobial activity, and excellent mechanical properties. Polymethyl methacrylate (PMMA), on the other hand, has many applications in medicine, biomedical systems, and engineering. However, its poor surface and mechanical properties limit its applications. The purpose of this study is how functionalization of PMMA would provide surface protection and reduce microbial adherence and biofilm formation. Hence, low-temperature Atomic Layer Deposition (ALD) was used to deposit TiO2, ZrO2, and TiO2/ZrO2 mixed oxides nanofilms on PMMA substrates. Surface composition was examined and Ti:Zr ratios were calculated through x-ray photoelectron spectroscopy. The coatings increased wettability and slightly enhanced nanohardness of PMMA. No significant change was observed in the surface roughness of PMMA after ALD. The nanocoatings protected the PMMA surface from thermal and brushing challenges by maintaining wettability, surface roughness, and film integrity. Additionally, compared to control, the mixed oxides with 1:2 cycle ratio of TiO2:ZrO2 showed a significant reduction on all bacterial and fungal initial adhesion and biofilm formation, while the TiO2 film provided reduction at initial fungal adhesion. Thus, TiO2/ZrO2 ALD on PMMA could enhance its surface, mechanical, and biological properties, preparing it for biomedical and engineering applications.

This paper proposes a digital-to-time converter (DTC)-assisted fractional-N wide-bandwidth all-digital phase-locked loop (ADPLL) with a fine-resolution time-to-digital converter (TDC). The TDC employs a two-channel time-interleaved time-domain register with an implicit adder/subtractor realizing an error-feedback topology. Such an error-feedback unit of a first-order $\Delta \Sigma $ -TDC can be cascaded as a multi-stage noise shaping configuration to achieve higher-order noise-shaping and, thereby, low in-band phase noise (PN) of the ADPLL. A digitally controlled oscillator with a transformer and a pair of cross-coupled NMOS amplifiers exploits magnetic and capacitive coupling to achieve nearly an octave frequency coverage, i.e., 1.73–3.38 GHz (after a $\div $ 2 division). Fabricated in 40-nm CMOS, the ADPLL achieves better than −110-dBc/Hz in-band PN and occupies an active area of 0.5 mm2. With a 50-MHz reference clock, a 2-GHz output RF clock, and a loop bandwidth of 800 kHz, this prototype achieves 420-fs $_{{\mathrm{rms}}}$ jitter, integrated from 1-kHz to 30-MHz offset, while drawing 10.7 mW.

In this paper, we propose a method to broaden a tuning range of a CMOS LC-tank oscillator without sacrificing its area. The extra tuning range is achieved by forcing a strongly coupled transformer-based tank into a common-mode resonance at a much higher frequency than in its main differential-mode oscillation. The oscillator employs separate active circuits to excite each mode but it shares the same tank, which largely dominates the core area but is on par with similar single-core designs. The tank is forced in common-mode oscillation by two injection locked Colpitts oscillators at the transformer's primary winding, while a two-port structure provides differential-mode oscillation. An analysis is also presented to compare the phase noise performance of the dual-core oscillator in common-mode and differential-mode excitations. A prototype implemented in digital 40-nm CMOS verifies the dual-mode oscillation and occupies only 0.12 mm2 and measures 56% tuning range.

In this paper, we propose a method to reduce a flicker (1/f) noise upconversion in voltage-biased RF oscillators. Excited by a harmonically rich tank current, a typical oscillation voltage waveform is observed to have asymmetric rise and fall times due to even-order current harmonics flowing into the capacitive part, as it presents the lowest impedance path. The asymmetric oscillation waveform results in an effective impulse sensitivity function of a nonzero dc value, which facilitates the 1/f noise upconversion into the oscillator's 1/f3 phase noise. We demonstrate that if the ω0 tank exhibits an auxiliary resonance at 2 ω0, thereby forcing this current harmonic to flow into the equivalent resistance of the 2 ω0 resonance, then the oscillation waveform would be symmetric and the flicker noise upconversion would be largely suppressed. The auxiliary resonance is realized at no extra silicon area in both inductor-and transformer-based tanks by exploiting different behaviors of inductors and transformers in differential-and common-mode excitations. These tanks are ultimately employed in designing modified class-D and class-F oscillators in 40 nm CMOS technology. They exhibit an average flicker noise corner of less than 100 kHz.

A fault-tolerant quantum computer with millions of quantum bits (qubits) requires massive yet very precise control electronics for the manipulation and readout of individual qubits. CMOS operating at cryogenic temperatures down to 4 K (cryo-CMOS) allows for closer system integration, thus promising a scalable solution to enable future quantum computers. In this paper, a cryogenic control system is proposed, along with the required specifications, for the interface of the classical electronics with the quantum processor. To prove the advantages of such a system, the functionality of key circuit blocks is experimentally demonstrated. The characteristic properties of cryo-CMOS are exploited to design a noise-canceling low-noise amplifier for spin-qubit RF-reflectometry readout and a class-F2,3 digitally controlled oscillator required to manipulate the state of qubits.

We present an ultra-low-power Bluetooth low-energy (BLE) transceiver (TRX) for the Internet of Things (IoT) optimized for digital 28-nm CMOS. A transmitter (TX) employs an all-digital phase-locked loop (ADPLL) with a switched current-source digitally controlled oscillator (DCO) featuring low frequency pushing, and class-E/F2 digital power amplifier (PA), featuring high efficiency. Low 1/ f DCO noise allows the ADPLL to shut down after acquiring lock. The receiver operates in discrete time at high sampling rate (10 Gsamples/s) with intermediate frequency placed beyond 1/ f noise corner of MOS devices. New multistage multirate charge-sharing bandpass filters are adapted to achieve high out-of-band linearity, low noise, and low power consumption. An integrated on-chip matching network serves to both PA and low-noise transconductance amplifier, thus allowing a 1-pin direct antenna connection with no external band-selection filters. The TRX consumes 2.75 mW on the RX side and 3.7 mW on the TX side when delivering 0 dBm in BLE.

We present a digital-to-time converter (DTC)-assisted fractional-N wide-bandwidth all-digital PLL (ADPLL). It employs a MASH ΔΣ time-to-digital converter (TDC) to achieve low in-band phase noise, and a wide-tuning range digitally-controlled oscillator (DCO). Fabricated in 40nm CMOS, the ADPLL consumes 10.7 mW while outputting 1.73 to 3.38 GHz (after a ÷2 division) and achieves better than −109 dBc/Hz in-band phase noise and 420fs rms integrated jitter.

We propose a new transmitter architecture for ultra-low power radios in which the most energy-hungry RF circuits operate at a supply just above a threshold voltage of CMOS transistors. An all-digital PLL employs a digitally controlled oscillator with switching current sources to reduce supply voltage and power without sacrificing its startup margin. It also reduces 1/f noise and supply pushing, thus allowing the ADPLL, after settling, to reduce its sampling rate or shut it off entirely during a direct DCO data modulation. The switching power amplifier integrates its matching network while operating in class-E/F2 to maximally enhance its efficiency at low voltage. The transmitter is realized in 28 nm digital CMOS and satisfies all metal density and other manufacturing rules. It consumes 3.6 mW/5.5 mW while delivering 0 dBm/3 dBm RF power in Bluetooth Low-Energy mode. European Research Council

This paper proposes a new RF oscillator topology that is suitable for ultra-low voltage and power applications. By employing alternating current source transistors, the structure combines the benefits of low supply voltage operation of conventional NMOS cross-coupled oscillators together with high current efficiency of the complementary push-pull oscillators. In addition, the 1/f noise upconversion is also reduced. The 40nm CMOS prototype exhibits an average FoM of 189.5 dBc/Hz over 4–5 GHz tuning range, dissipating 0.5mW from 0.5V power supply, while abiding by the technology manufacturing rules.

This paper presents a CMOS temperature sensor intended for the temperature compensation of MEMS frequency references. It is based on a Wien bridge RC filter, whose phase-shift, due to the temperature dependency of the resistors used, is temperature dependent. This phase shift is then digitized by a phase domain sigma-delta modulator. The sensor was implemented in 0.18μm CMOS, consumes 36 μW and achieves 6mK resolution in a conversion time of 100msec. After batch calibration and a 3-point trim, it achieves ±0.15°C (3σ) inaccuracy over the industrial range (-40°C to 85°C).

Quantum computing holds the promise to achieve unprecedented computation power and to solve problems today intractable. State-of-the-art quantum processors consist of arrays of quantum bits (qubits) operating at a very low base temperature, typically a few tens of mK, as shown in Fig. 15.5.1 The qubit states degrade naturally after a certain time, upon loss of quantum coherence. For proper operation, an error-correcting loop must be implemented by a classical controller, which, in addition of handling execution of a quantum algorithm, reads the qubit state and performs the required corrections. However, while few qubits (∼10) in today's quantum processors can be easily connected to a room-temperature controller, it appears extremely challenging, if not impossible, to manage the thousands of qubits required in practical quantum algorithms [1].