Open AccessLow noise, −50 dB second harmonic distortion single‐ended to differential switched‐capacitive variable gain amplifier for ultrasound imaging
Author(s) -
Wang Peng,
Ytterdal Trond
Publication year - 2016
Publication title -
iet circuits, devices and systems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.251
H-Index - 49
ISSN - 1751-8598
DOI - 10.1049/iet-cds.2014.0364
Subject(s) - video graphics array , variable gain amplifier , total harmonic distortion , automatic gain control , amplifier , electrical engineering , fully differential amplifier , capacitor , low noise amplifier , noise (video) , physics , materials science , operational amplifier , voltage , cmos , engineering , computer science , artificial intelligence , image (mathematics)
A low noise, low power, single‐ended to differential switched‐capacitor variable gain amplifier (SC‐VGA) is designed and fabricated in 0.18 µm complementary metal‐oxide‐semiconductor technology for a 2–6 MHz second harmonic cardiac ultrasound imaging system. The SC‐VGA has 10‐bit dB‐linear gain steps from −14 to 32 dB which are distributed into two stages, and each stage has a single‐stage operational trans‐conductance amplifier using floating capacitors to save the power and improve the noise performance. The first stage converts the single‐ended input to differential outputs with the 2‐bit gain control from 0 to 18 dB, and the second stage exploits 8‐bit capacitor arrays to control the gain from −14 to 14 dB. The measured results show that the second harmonic distortion is <−50 dB, the third harmonic distortion is <−50 dB and the integrated noise from 2 to 6 MHz at the output is −64 dBm at the maximum gain and a sampling frequency of 30 MHz. The simulation results match well with the measured results. The SC‐VGA works at a supply voltage of 1.6 V and consumes the current of 900 µA. The die size of the SC‐VGA is 387 µm × 502 µm.