A CMOS four-quadrant analog current multiplier

A CMOS four-quadrant analog current multiplier is described. The circuit is based on the square-law characteristic of an MOS transistor and is insensitive to temperature and process variations. The circuit is insensitive to the body effect so it is not necessary to place transistors in individual wells. The multiplier has a large -3-dB bandwidth (50 MHz with 10-¿m transistors) and an approximately constant input impedance. The circuit was realized on a CMOS semicustom array. Measurements have shown that the nonlinearity is less than 1% at the maximum input current range and less than 0.2% when the input range is restricted to 50% of the maximu

A CMOS Wideband Linear Current Attenuator with Electronically Variable Gain

A CMOS highly linear current attenuator is described. The circuit is suited for both differential and single input currents. The current gain is electronically variable between -1 and +1 by means of two controlling currents. A simple additional circuit is described to obtain a gain that is linearly dependent on a single control current. The circuit can be used as a four-quadrant current multiplier. The current attenuator is realized in a standard 2.5 μm CMOS process using channel lengths of 5 μm. The measured nonlinearity is less than 1% over the entire input current range. Simulations indicate a feasible -3dB bandwidth of over 100 MHz

A high-Tc 4-bit periodic threshold analog-to-digital converter

Using ramp-type Josephson junctions a 4-bit periodic threshold ADC has been designed, fabricated and tested. Practical design constraints will be discussed in terms of noise immunity, flux flow, available technology, switching speed etc. In a period of four years we fabricated about 100 chips in order to bring the technology to an acceptable level and to test various designs and circuit layouts. This resulted in a basic comparator that is rather insensitive to the stray field generated by the analog input signal or variations in mask alignment during fabrication. The input signal is fed into the comparators using a resistive divider network. Full functionality at low frequencies has been demonstrate

A low-voltage Op Amp with rail-to-rail constant-gm input stage and a class AB rail-to-rail output stage

In this paper a low-voltage two-stage Op Amp is presented. The Op Amp features rail-to-rail operation and has an @put stage with a constant transconductance (%) over the entire common-mode input range. The input stage consists of an n- and a PMOS differential pair connected in parallel. The constant gm is accomplished by regulating the tail-currents with the aid of an MOS translinear (MTL) circuit. The resulting gn is constant within 5% The common-source output stage employs a feedback circuit which also contains an MTL circuit. This feedback circuit ensures class AB operation and prevents the transistors in the output stage from cutting off. The Op Amp will be realized in a semi custom CMOS process with minimum channel lengths of 1Opm. Simulations show that the minimum supply voltage is less than 2.5 V. A unity gain bandwidth of 550 kHz and a DC voltage gain larger than 80 dB are feasible. The input range exceeds the supply rails, whereas the output range reaches the rails within 130 mV

Air Damping Analysis of a Micro-Coriolis Mass Flow Sensor

A micro-Coriolis mass flow sensor is a resonating device that measures small mass flows of fluid. A large vibration amplitude is desired as the Coriolis forces due to mass flow and, accordingly, the signal-to-noise ratio, are directly proportional to the vibration amplitude. Therefore, it is important to maximize the quality factor Q so that a large vibration amplitude can be achieved without requiring high actuation voltages and high power consumption. This paper presents an investigation of the Q factor of different devices in different resonant modes. Q factors were measured both at atmospheric pressure and in vacuum. The measurement results are compared with theoretical predictions. In the atmospheric environment, the Q factor increases when the resonance frequency increases. When reducing the pressure from 1 bar to 0.1 bar, the Q factor almost doubles. At even lower pressures, the Q factor is inversely proportional to the pressure until intrinsic effects start to dominate, resulting in a maximum Q factor of approximately 7200.</p

Low creep and hysteresis silicon load cell based on a force-to-liquid pressure transformation

Important problems in load cells are creep and hysteresis. Expensive high grade steels are used in order to reduce these effects. In this paper a silicon load cell design is presented which is based on a force-to-liquid-pressure transformation. The design is insensitive to hysteresis and creep, can be made at very low costs and is able to measure loads up to 1000 kg with an accuracy of 0.03 %. Analytical, numerical and experimental results on a macroscopic steel load cell are in very close agreement with each other

Modeling, Fabrication, and Testing of a 3D-Printed Coriolis Mass Flow Sensor

This paper presents the modeling, fabrication, and testing of a 3D-printed Coriolis mass flow sensor. The sensor contains a free-standing tube with a circular cross-section printed using the LCD 3D-printing technique. The tube has a total length of 42 mm, an inner diameter of about 900 µm, and a wall thickness of approximately 230 µm. The outer surface of the tube is metalized using a Cu plating process, resulting in a low electrical resistance of 0.5 Ω. The tube is brought into vibration using an AC current in combination with a magnetic field from a permanent magnet. The displacement of the tube is detected using a laser Doppler vibrometer (LDV) that is part of a Polytec MSA-600 microsystem analyzer. The Coriolis mass flow sensor has been tested over a flow range of 0–150 g/h for water, 0–38 g/h for isopropyl alcohol (IPA), and 0–50 g/h for nitrogen. The maximum flow rates of water and IPA resulted in less than a 30 mbar pressure drop. The pressure drop at the maximum flow rate of nitrogen is 250 mbar.</p