A Digitally Controlled Variable Gain Amplifier for Ultrasound Imaging Applications

Vinay Alexander, Aaron Eash, Scott Rudolph

Abstract

Our project is to design a variable gain amplifier (VGA) with the specific target application of ultrasound imaging. In ultrasound VGAs are needed to account for extreme variations in acoustic damping (>110 dB) within the received signal [1]. We will design a VGA producing discrete gain values beyond a frequency of 20 MHz. To implement this design we will create a temperature and process invariant current source for biasing. We will then design a variable gain amplifier using an amplifier bypass scheme. Our goal is to design a variable gain amplifier with specifications comparable to current industry standards. We also hope to make the key parameters such as gain, input and output impedances minimally dependant on temperature and process variations.

References

  1. "Optimizing Ultrasound-Receiver VGA Output-Referred Noise and Gain: Improves Doppler Dynamic Range and Sensitivity." Maxim Application Note 4038, [Online] at http://www.maxim-ic.com/appnotes.cfm/an_pk/4038. Nov 2007.

Files