Publication detail

Evaluation of characteristics of an HV electrometric amplifier with low input current

ROUBAL, Z. KADLEC, R.

Original Title

Evaluation of characteristics of an HV electrometric amplifier with low input current

English Title

Evaluation of characteristics of an HV electrometric amplifier with low input current

Type

journal article

Language

en

Original Abstract

In certain special applications, for example in various fields of chemistry, it is necessary to measure voltage in the order of hundreds of volts from a high-impedance source. Standard electrometric operational amplifiers cannot be used as their input range is limited to the maximum of ten volts. Furthermore, it is impossible to increase the input range by a voltage divider in situations when the required input resistance is, for example, 10^14 Ohm. A common resistive divider in the input of an operational amplifier typically shows the maximum input resistance of 10^12 Ohm. A special circuit arrangement can be used in which the amplifier supply voltage is dynamically shifted with the input voltage. This configuration saves the high input resistance of the applied electrometric amplifier and extends the input voltage range to the desired value. In our configuration, the extended range is +-300 V. The proposed design of an HV electrometric amplifier utilizes a high-voltage differential amplifier, which regulates the high-voltage source supplying the electrometric operational amplifier. The general feedback loop has to be frequency-compensated, and this compensation is designed using the Pspice simulator. Characteristics of the HV electrometric amplifier were confirmed by the measurement of freezing potentials.

English abstract

In certain special applications, for example in various fields of chemistry, it is necessary to measure voltage in the order of hundreds of volts from a high-impedance source. Standard electrometric operational amplifiers cannot be used as their input range is limited to the maximum of ten volts. Furthermore, it is impossible to increase the input range by a voltage divider in situations when the required input resistance is, for example, 10^14 Ohm. A common resistive divider in the input of an operational amplifier typically shows the maximum input resistance of 10^12 Ohm. A special circuit arrangement can be used in which the amplifier supply voltage is dynamically shifted with the input voltage. This configuration saves the high input resistance of the applied electrometric amplifier and extends the input voltage range to the desired value. In our configuration, the extended range is +-300 V. The proposed design of an HV electrometric amplifier utilizes a high-voltage differential amplifier, which regulates the high-voltage source supplying the electrometric operational amplifier. The general feedback loop has to be frequency-compensated, and this compensation is designed using the Pspice simulator. Characteristics of the HV electrometric amplifier were confirmed by the measurement of freezing potentials.

Keywords

Freezing potencial, Electrometric amplifier

RIV year

2011

Released

22.09.2011

Pages from

995

Pages to

999

Pages count

5

BibTex


@article{BUT73499,
  author="Zdeněk {Roubal} and Radim {Kadlec}",
  title="Evaluation of characteristics of an HV electrometric amplifier with low input current",
  annote="In certain special applications, for example in various fields of chemistry, it is necessary to measure voltage in the order of hundreds of volts from a high-impedance source. Standard electrometric operational amplifiers cannot be used as their input range is limited to the maximum of ten volts. Furthermore, it is impossible to increase the input range by a voltage divider in situations when the required input resistance is, for example, 10^14 Ohm.  A common resistive divider in the input of an operational amplifier typically shows the maximum input resistance of 10^12 Ohm. A special circuit arrangement can be used in which the amplifier supply voltage is dynamically shifted with the input voltage. This configuration saves the high input resistance of the applied electrometric amplifier and extends the input voltage range to the desired value. In our configuration, the extended range is +-300 V. The proposed design of an HV electrometric amplifier utilizes a high-voltage differential amplifier, which regulates the high-voltage source supplying the electrometric operational amplifier. The general feedback loop has to be frequency-compensated, and this compensation is designed using the Pspice simulator. Characteristics of the HV electrometric amplifier were confirmed by the measurement of freezing potentials.",
  chapter="73499",
  number="2011",
  volume="2011",
  year="2011",
  month="september",
  pages="995--999",
  type="journal article"
}