{"id":1405,"date":"2010-07-07T09:59:06","date_gmt":"2010-07-07T13:59:06","guid":{"rendered":"https:\/\/wpmu2.mit.local\/?p=1405"},"modified":"2010-07-26T14:25:55","modified_gmt":"2010-07-26T18:25:55","slug":"an-sar-adc-with-adiabatic-charging-for-use-in-medical-implants","status":"publish","type":"post","link":"https:\/\/wpmu2.mit.local\/an-sar-adc-with-adiabatic-charging-for-use-in-medical-implants\/","title":{"rendered":"A SAR ADC with Adiabatic Charging for Use in Medical Implants"},"content":{"rendered":"
\"Figure<\/a>

Figure 1: 8-bit SAR ADC topology with step charging on three largest capacitors.<\/p><\/div>\n

The proposed research program has two primary goals. The first goal is to improve the evaluation and treatment of patients with diabetes and a variety of movement disorders including Parkinson\u2019s disease, restless leg syndrome, and essential tremor, by allowing doctors to continuously monitor relevant biomarkers over much longer time scales and with better precision than currently possible. The second goal is that the proposed implant be a platform<\/em> for electronic sensory monitoring that is inexpensive and flexible and that can be used with a wide variety of sensors and for a wide variety of purposes, such as chemical sensors for monitoring blood chemistry.\u00a0 In this work, we develop an energy-efficient analog-to-digital converter designed to operate with a power management scheme using ultracapacitors as opposed to a battery.<\/p>\n

\"Figure<\/a>

Figure 2: Self-stabilizing circuit to generate ramp voltage.<\/p><\/div>\n

Two techniques are employed to save on energy for the entire system.\u00a0 The first is to use adiabatic charging [1<\/a>]<\/sup> [2<\/a>]<\/sup> of the capacitors contained in the SAR ADC.\u00a0 This application is ideal for adiabatic techniques because of the low frequency of operation and the ease at which we can reclaim energy from discharging the capacitors.\u00a0 Figures 1 and 2 show the necessary circuits for implementing the adiabatic charging.\u00a0 The second technique is to employ compressive sampling (CS) [3<\/a>]<\/sup> [4<\/a>]<\/sup> to sample slower than the Nyquist rate.\u00a0 Leveraging the fact that tremor data is sparse in the frequency domain, we can implement the CS technique before the ADC to save energy and decrease the size of the memory.\u00a0 In our application, both of energy and size are important bottlenecks because the ADC is the dominant power consumer, and memory size is a significant factor for long-term data storage.<\/p>\n

\r\nReferences
  1. L.J. Svensson and J.G. Koller, \u201cDriving a capacitive load without dissipating fCV2<\/sup><\/em>,\u201d in IEEE Symposium on Low Power Electronics<\/em>, pp. 100-101, Oct. 1994. [↩<\/a>]<\/li>
  2. J.G Koller and L.J. Svensson, \u201cAdiabatic charging without inductors,\u201d USC\/ISI technical report ACMOSTR-3a<\/em>, Feb. 8, 1994. [↩<\/a>]<\/li>
  3. E. Candes, \u201cCompressive sampling,\u201d Int. Congress of Mathematics<\/em>, 3, pp. 1433-1452, Madrid, Spain, 2006. [↩<\/a>]<\/li>
  4. P. Bofounos, J. Romberg, and R. Baraniuk, \u201cCompressive sensing \u2013 theory and applications,\u201d in IEEE Int. Conf on Acoustics, Speech, and Signal Processing (ICASSP)<\/em>, Las Vegas, Nevada, Apr. 2008. [↩<\/a>]<\/li><\/ol><\/div>","protected":false},"excerpt":{"rendered":"

    The proposed research program has two primary goals. The first goal is to improve the evaluation and treatment of patients…<\/p>\n<\/div>","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[26,27],"tags":[49,4149],"_links":{"self":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts\/1405"}],"collection":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/comments?post=1405"}],"version-history":[{"count":5,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts\/1405\/revisions"}],"predecessor-version":[{"id":1411,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/posts\/1405\/revisions\/1411"}],"wp:attachment":[{"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/media?parent=1405"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/categories?post=1405"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpmu2.mit.local\/wp-json\/wp\/v2\/tags?post=1405"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}