Analysis and design of voltage‐controlled current sources for a grounded load

Пандиев, И. М.

doi:10.1002/cta.1971

Cited by 9 publications

(10 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The modeling of the above circuit, also discussed in [16], is reproduced here for didactic reasons and, more importantly, to describe the design constraints of a power HCS able to output a load-independent current proportional to the input voltage. Subsection II-A deduces both the output current i L as a function of the input voltage v i and the conditions necessary to maintain this relationship true regardless of the load.…”

Section: Howland Current Sourcementioning

confidence: 99%

See 1 more Smart Citation

Howland Current Source Applied to Magnetic Field Generation in a Tri-Axial Helmholtz Coil

et al. 2019

View full text Add to dashboard Cite

This work describes the design and testing of a power Voltage-Controlled Current Source (VCCS) based on the Howland Current Source (HCS) topology. This source is part of a system that contains a three-axial Helmholtz coil and is used to generate a controlled magnetic field environment for aerospace applications. Initially, the paper presents the HCS theory and practical limitations on the premise that the system must be built using low-cost off-the-shelf components. The paper also carefully address on how to design and plan the VCCS matching physical and electrical parameters/limitations of a specific Helmholtz coil. All project details as well as the built VCCS electronics and its results are shown. These include linearity and a first order calibration test, stability and low-frequency error measurement, step response and a frequency limitation analysis. The built source is capable of sourcing up to ±1.5 A at ±25 V, maintaining its linearity and achieving an error smaller than 0.5% with a first order calibration. The final HCS prototype together with the Helmholtz coil allows an excellent capability regarding magnetic field generation for both open and closed-loop applications.

show abstract

Section: Howland Current Sourcementioning

confidence: 99%

“…Combining (8) with (16) and after some algebraic manipulation, (17) describes the relationship between the relative rate of change of the current load as function of the resistor's TCR and the relative rate of change of the input voltage, within a specified temperature range.…”

Section: B Hcs Stability Due To R 2b Temperaturementioning

confidence: 99%

Howland Current Source Applied to Magnetic Field Generation in a Tri-Axial Helmholtz Coil

et al. 2019

View full text Add to dashboard Cite

show abstract

“…At the circuit board level, the simplest ways to build such current source is to apply a linear voltage ramp to a differentiation capacitor or to use precision both voltage references and resistor in order to increase the system accuracy and ensure it over time [ 25 , 26 ]. However, they are mainly realized starting from op-amps acting as Voltage-to-Current (V-I) converters (i.e., transconductance amplifiers) [ 27 ]. V-I converters accept a voltage as input to source or sink a current from a load.…”

Section: Introductionmentioning

confidence: 99%

Compact Current Reference Circuits with Low Temperature Drift and High Compliance Voltage

Pettinato

Orsini

Salvatori

2020

Sensors

View full text Add to dashboard Cite

Highly accurate and stable current references are especially required for resistive-sensor conditioning. The solutions typically adopted in using resistors and op-amps/transistors display performance mainly limited by resistors accuracy and active components non-linearities. In this work, excellent characteristics of LT199x selectable gain amplifiers are exploited to precisely divide an input current. Supplied with a 100 µA reference IC, the divider is able to exactly source either a ~1 µA or a ~0.1 µA current. Moreover, the proposed solution allows to generate a different value for the output current by modifying only some connections without requiring the use of additional components. Experimental results show that the compliance voltage of the generator is close to the power supply limits, with an equivalent output resistance of about 100 GΩ, while the thermal coefficient is less than 10 ppm/°C between 10 and 40 °C. Circuit architecture also guarantees physical separation of current carrying electrodes from voltage sensing ones, thus simplifying front-end sensor-interface circuitry. Emulating a resistive-sensor in the 10 kΩ–100 MΩ range, an excellent linearity is found with a relative error within ±0.1% after a preliminary calibration procedure. Further advantage is that compliance voltage can be opposite in sign of that obtained with a passive component; therefore, the system is also suitable for conditioning active sensors.

show abstract

“…Another drawback is the increasingly significant power loss that occurs if the voltage at the current delivery node rises. The improved Howland current pump reduces the effects of these shortcomings. It is capable of delivering a low value of constant current into high‐resistance loads since the voltage at the output node can rise to higher values.…”

Section: Introductionmentioning

confidence: 99%

“…The system works extremely well at low frequencies, and many variations of the basic topology have been introduced that increase its range of applications. These latter applications include bridge configurations that minimize common‐mode interference, circuits with lead‐lag compensation for higher frequency response and improved stability, circuits that use power amplifiers and additional power transistors, and several other systems . In this paper, an enhanced version of the improved Howland current pump is presented.…”

Section: Introductionmentioning

confidence: 99%