Edgar Charry Rodríguez

A Low Power CMOS Voltage Regulator for a Wireless Blood Pressure Biosensor

This paper describes a CMOS implementation of a linear voltage regulator (LVR) used to power up implanted physiological signal systems, as it is the case of a wireless blood pressure biosensor. The topology is based on a classical structure of a linear low-dropout regulator. The circuit is powered up from an RF link, thus characterizing a passive radio frequency identification (RFID) tag. The LVR was designed to meet important features such as low power consumption and small silicon area, without the need for any external discrete components. The low power operation represents an essential condition to avoid a high-energy RF link, thus minimizing the transmitted power and therefore minimizing the thermal effects on the patients tissues. The project was implemented in a 0.35-μm CMOS process, and the prototypes were tested to validate the overall performance. The LVR output is regulated at 1 V and supplies a maximum load current of 0.5 mA at 37°C. The load regulation is 13 mV/mA, and the line regulation is 39 mV/V. The LVR total power consumption is 1.2 mW.

New Architecture for Intelligent Pressure Sensors with Analog and Digital Outputs

This article proposes a new architecture for intelligent pressure sensors based on the interconnection of a Digital Signal Processor (DSP) and a microcontroller. This configuration allows to obtain a highly accurate output using a reduced number of electronic components. Additionally, very low response times are obtained and different protocols for digital communication are implemented. This paper also discusses the compensation algorithm used to correct the sensitivity and offset dependence on temperature, as well as non-linearity of the pressure sensor response. Hardware and tests performed to verify the proposed architecture operation are described. The total error band obtained in the digital output was 0.07% of full scale output for a relative pressure sensor in a temperature range of 0 to 50 °C. The obtained results demonstrate the advantages of the new architecture proposed.

A CMOS Linear power supply for a Wireless Biomedical Sensor

This paper describes a CMOS Linear Voltage Regulator (LVR) of an implanted physiological signal system (biosensor) that is used to monitor blood pressure. This system is part of a Wireless Biomedical Sensor (WBS). The LVR topology is based on a classical structure of a Low Dropout Regulator (LDO). The energy is received from a RF link, thus operating as a passive RFID tag. The LVR was designed to achieve important features like low power consumption, and a small silicon area without the need for any external discrete components. The low power operation represents an essential condition to avoid a high energy RF link, thus minimizing the power of the transmitter and the thermal effects on the patients tissues. It was implemented in a 0.35 µm CMOS process and the prototypes were tested to validate the overall performance.

Biomedical signals monitoring based in mobile computing

The main objective of this project consists in the development of a biomedical instrumentation prototype for acquisition, processing and transmission of biomedical signals. These biomedical signals are acquired and then processed with a microcontroller. After processing, all data are sent to a communication interface that can send this information to a personal computer or a cell phone. The prototype developed, which is a digital blood pressure meter, is intended to allow remote monitoring of patients living in areas with limited access to medical assistance or scarce clinical resources. We believe that this development could be helpful to improve peoples quality of life, as well as to allow an improvement in the government attendance indices.