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Purpose The purpose of this work in designing a wideband ring voltage-controlled oscillator (VCO) based on programmable current topology. It occupies a very tiny area yet achieving a good phase noise performance, which is suitable to be implemented in cost-effective and wideband frequency synthesizers.Design/methodology/approach The tuning range and gain are improved by dividing the VCO tuning curve into multiple curves controlled by programmable current sources without introducing additional parasitic capacitance.Findings Fabricated in 130-nm standard complementary metal oxide semiconductor technology and occupying an area of 0.079 mm2, the VCO is tunable from 2.05 to 4.19 GHz, with a tuning percentage of 68.5 per cent. The VCO measures a phase noise performance of −96.7 dBc/Hz at an offset of 1 MHz from a 4.19 GHz carrier while consuming an average current of 6.5 mA, achieving figure of merit (FoM) and FoMT of −158.9 and −175.6 dBc/Hz, respectively.Originality/value The proposed design uses programmable current topology without introducing parasitic capacitance, hence achieving wideband operation. It also occupies a tiny area and achieves a good phase noise performance. [ABSTRACT FROM AUTHOR]

This paper presents a selector–combiner (SC) circuit for use as a constituent block for a multi-pixel complementary metal-oxide-semiconductor (CMOS) photon detector. The circuit essentially allows signal from pixels of interest to be summed and output. This pixel-selection configurability may enhance imaging performance and also produce different imaging effects for various analyses. A 9-to-1 SC circuit was designed and fabricated in an Austriamicrosystems (AMS) 0.35 µm process technology. The worst-case linear working range at the input was found to be between 1.50 and 1.80 V, occurring when all inputs were enabled. It exhibited an insignificant signal loss of about −0.96 dB when all inputs were enabled. The circuit has been proven to achieve a minimum bandwidth of 7.2 MHz. Simulated and experimental results have shown that signal addition can be performed effectively and the circuit is suitable to be integrated into a multi-pixel CMOS photon detector. [ABSTRACT FROM PUBLISHER]

In this paper, a novel integrated solid-state solution is proposed to replace the vacuum-based photomultiplier tube and other constituent components of the Everhart-Thornley detector, which has been widely used for secondary electron detection in scanning electron microscopy. Compared to the conventional setup, this integrated circuit offers potential merits such as higher cost effectiveness, smaller dimensions, lower voltage and power requirements, and better circuit integration. It was designed and fabricated in an optically-enhanced Austriamicrosystems 0.35 μm CMOS process technology. Results from simulations and experiments have shown that the solid-state detector can operate with a maximum transimpedance gain of 170 dBΩ and minimum bandwidth of 3.6 MHz. It can detect signals with optical power as low as 10 nW while giving a minimum signal-to-noise ratio of 24 dB regardless of gain configuration. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to design a very low-noise transimpedance amplifier (TIA) for a novel multi-pixel CMOS photon detector which performs secondary electron (SE) detection in the scanning electron microscope (SEM). Design/methodology/approach – The TIA, which is implemented with three-stage push-pull inverters, is optimised using a nomograph technique developed in MATLAB. SPICE simulations are conducted to verify the results generated from MATLAB. Important performance figures are obtained experimentally and these measurements are compared with simulation results. Findings – A low-noise TIA fabricated in a standard 0.35 μm CMOS technology was tested. Experimental results obtained show that the TIA connected to a photodiode with a junction capacitance of 0.8 pF can carry out its task effectively with a transimpedance gain of 126.9 dBΩ, a bandwidth of 9.8 MHz, an input-referred noise of 2.50x10-13 A/➃Hz and an SNR of 12.8. The power consumption of the TIA was 49.3 mW. These encouraging results have exhibited the potential of the circuit for use in the CMOS photon detector. Originality/value – This paper presents a low-noise transimpedance amplifier that is highly suitable to be used as a critical constituent block for the CMOS photon detector which aims to take over the role of photomultiplier tube in SE detection in the SEM. Solid-state approaches have recently been reinvigorated for improving certain aspects of SE detection in scanning electron microscopy and this work has supported and contributed to the trend. [ABSTRACT FROM AUTHOR]