Title :
A low noise preamplifier for AC bridges
Author :
Zhao Jianting ; Lu Yunfeng ; He Qing
Author_Institution :
Nat. Inst. of Metrol., Beijing, China
Abstract :
This paper describes the design, schematics, and performance of a very low-noise J-EFT preamplifier. The amplifier has a gain flatness better than 1dB in the 500Hz to 1MHz frequency region. Noise measurements on this amplifier yield a voltage noise less 0.5nV/√Hz and current noise less 1fA/√Hz in the 100Hz to 100kHz frequency region. It could be used as the preamplifier of the null detector of AC bridges. With modest changes it could be extended to a wide variety of uses requiring low noise gain.
Keywords :
bridge circuits; circuit noise; junction gate field effect transistors; low noise amplifiers; preamplifiers; AC bridges; J-FET preamplifier; amplifier yield; current noise; frequency 500 Hz to 1 MHz; gain flatness; low noise preamplifier; noise measurements; null detector; Bridge circuits; Capacitance; Current measurement; Detectors; Noise; Noise measurement; Preamplifiers; J-EFT amplifier; cascade; low noise preamplifiers; null detector;
Conference_Titel :
Precision Electromagnetic Measurements (CPEM), 2012 Conference on
Conference_Location :
Washington, DC
Print_ISBN :
978-1-4673-0439-9
DOI :
10.1109/CPEM.2012.6251069
