1. Цифровая обработка сигналов (цос)



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Isolated Thermocouple

1
6-Bit Analog-to-Digital Converter For Temperature Sensors

Diagram

Analog to Digital Converters

F
unctional Diagram

Description

The ADS1146, ADS1147, and ADS1148 are highly-integrated, precision, 16-bit analog-to-digital converters (ADCs). The ADS1146/7/8 feature an onboard, low-noise, programmable gain amplifier (PGA), a precision delta-sigma ADC with a single-cycle settling digital filter, and an internal oscillator. The ADS1147 and ADS1148 also provide a built-in voltage reference with 10mA output capacity, and two matched programmable current digital-to-analog converters (DACs). The ADS1146/7/8 provide a complete front-end solution for temperature sensor applications including thermal couples, thermistors, and resistance temperature detectors (RTDs).

An input multiplexer supports four differential inputs for the ADS1148, two for the ADS1147, and one for the ADS1146.

Features (View full Description in Datasheet)

  • 16 Bits, No Missing Codes

  • Data Output Rates Up to 2kSPS

  • Single-Cycle Settling for All Data Rates

  • Simultaneous 50/60Hz Rejection at 20SPS

  • 4 Differential/7 Single-Ended Inputs (ADS1148)

  • 2 Differential/3 Single-Ended Inputs (ADS1147)

  • Matched Current Source DACs

  • Internal Voltage Reference

  • Sensor Burnout Detection

  • 4/8 General-Purpose I/Os (ADS1147/8)

  • Internal Temperature Sensor

  • Power Supply and VREF Monitoring (ADS1147/8)

  • Self and System Calibration

  • SPI-Compatible Serial Interface

  • Analog Supply Operation: +2.7V to +5.25V Unipolar, ±2.5V Bipolar

  • Digital Supply: +2.7V to +5.25V

  • Operating Temperature –40°C to +125°C

  • APPLICATIONS: Temperature Measurement (RTDs, Thermocouples, and Thermistors)

2.9. MRI: Magnetic Resonance Imaging (МРТ: Магнитно-резонансная томография)

Magnetic Resonance Imaging (MRI) uses radio-frequency waves and a strong magnetic field rather than x-rays to provide remarkably clear and detailed 2-D and 3-D pictures of internal organs and tissues.

Block Diagram


Design Considerations


Magnetic Resonance Imaging (MRI) is a non-invasive diagnostic technology that produces physiologic images based on the use of magnetic and radio frequency (RF) fields. The MRI system uses powerful magnets to create a magnetic field which forces hydrogen atoms in the body into a particular alignment (resonance). Radio frequency energy is then distributed over the patient, which is disrupted by body tissue. The disruptions correspond to varying return signals which, when processed, create the image.

The accurate processing of these signals is key to obtaining high quality images. A key system consideration for the receive channel is high SNR. The return signals have narrow bandwidths with an IF location directly dependent on the main magnet s strength. Some systems use high-speed pipeline ADCs with wideband amplifiers to directly sample the IF, leaving large headroom for post-processing gain by a digital down converter or FPGA. Other systems mix the IF to baseband where lower-speed, higher-resolution SAR and delta-sigma ADCs can be used.

For controlling the magnetic and RF energy in the MRI, high-resolution, high-speed DACs are needed. High resolution is required to accurately define the area of the patient to be scanned. High-speed is necessary to match the high IFs being generated by the main magnet. DSPs can be used to provide gradient processor control used for properly controlling the magnets in the MRI system. A DSP can also take care of preprocessing the signal before it reaches the image reconstruction engine.

A wide variety of TI products are available for MRI systems and equipment manufacturers, including op amps, DSPs, multi-channel high- and low-speed data converters, clocking distribution, interface, and power management.



2.10. Medical Meters: Portable (Медицинские метры: Портативные)

Portable Medical Instruments such as blood glucose meter, digital blood pressure meter, blood gas meter, digital pulse/heart rate monitor or even a digital thermometer leverage five system level blocks that are common to each.

B
lock Diagram




Design Considerations

Portable Medical Instrument Design

Portable Medical Instruments device design: blood glucose meter design, blood gas meter, digital pulse/heart rate monitor and digital thermometer design.

What's New


Go passive. Go battery free! With the Passive Low Frequency Interface Device (PaLFI) TMS37157, power your microcontroller, sensor, and sensor interface at short range by the PaLFI interface without a battery.

Whether developing a glucose meter, blood pressure meter, blood gas meter, digital thermometer, or a heart rate monitor there are system level blocks that are common to each: Power/Battery Management, Control and Data processing, Amplification and A/D Conversion, a display, and the sensor element itself. These are microcontroller controlled handheld devices that operate on battery and take measurements using various bio-sensors, with the topology of these blocks differing with the sensing, processing and information display demands of the meter type and feature set.



Power consumption is key, driven by the need for extended battery life, and high precision with a fast response time. Requirements such as wireless or wired connectivity, historical data profiling and audio or voice feedback drives the need for microcontrollers with adequate memory. Texas Instruments' portfolio of Microcontrollers, Instrumentation and Buffer Amplifiers, Wireless and Wired interface devices, Power and Battery Management, and Audio Amplifiers provides the ideal tool box for portable medical applications.

The common core subsystems are:

  • Analog Front-End/Sensor Interface - Bio-sensor signals in portable meters are slow moving and very low in amplitude. Front-end amplification may be required prior to A/D conversion. Front-end excitation, if required, can be accomplished with a discrete or integrated DAC within the microcontroller.

  • Microcontroller - The Microcontroller executes the signal measuring processes and controls interface with memory and peripheral devices. As power consumption is critical, the broad product portfolio of the Ultra low power MSP430 family makes it an ideal processor choice. Their high level of integration simplifies the design and reduces system cost as buffer amplifiers, data conversion, LCD controllers, and user/keypad interface are provided.

  • Connectivity - Power consumption, data rate and range are the three key considerations when selecting a wireless interface. The Zigbee protocol provides worldwide coverage, a moderate data rate and duty cycle, and supports a mesh network allowing multiple sensors in the same system with a wide range. Bluetooth and Bluetooth Low Energy® protocols provide for limited range but higher data rate.
    Passive Low Frequency Interface products (PaLFI) are not only capable of providing near field wireless connectivity, but depending on your system power consumption, PaLFI is capable of powering your complete system.

  • Power Management and Conversion - Making power management decisions early in the design cycle will help define system-level tradeoffs necessary to meet run-time targets. Smaller portable medical products may use disposable batteries, whereas larger portable systems might leverage rechargeable battery chemistries. Features such as dynamic power path management (DPPM) permit the system to draw power independently of the battery charging path. This allows a device with completely discharged batteries to be used as soon as it is plugged in, rather than waiting for the batteries to recharge. Also look for features such as Impedance tracking or battery authentication when safety and system reliability is critical.

  • Audio Amplifier - The Audio Amplifier amplifies the audio signal coming either from a PWM circuit or a DAC which can be used to notify users when measuring results are available for example. The DAC is capable to output voice instructions from speech-synthesizer software.


2.11. Patient Monitoring (Мониторинг пациентов)

Каталог: wp-content -> uploads -> 2015
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