MIKROE-2621 EMG click board™

The MIKROE-2621 EMG click from MikroElektronika measures the electrical activity produced by the skeletal muscles. It features the Microchip MCP609 operational amplifier as well as the Maxim MAX6106 micropower voltage reference. EMG click is designed to run on a 5 V power supply and it has an analog output (AN pin). The EMG click is a prototyping tool, not a medical-grade device, so it is not to be used to diagnose patients. Electromyography or EMG is a diagnostic technique for measuring the electrical activity of muscles. It is often used to diagnose the health of these muscles and the neurons that control them. These neurons are called motor neurons. They transmit electrical signals and the muscles contract when this happens. The onboard 3.5 mm audio jack is used to connect cables/electrodes to the click board. The electrode collects voltage from the skin (few millivolts) and the signal from the jack is amplified and filtered. Therefore, EMG click can be divided into seven blocks.

The MCP609 operational amplifiers from Microchip Technology are unity-gain stable with low offset voltage (250 µV, maximum). Performance characteristics include rail-to-rail output swing capability and low input bias current (80 pA at +85°C, maximum). These features make this family of op amps well suited for single-supply, precision, high-impedance, industrial process control, low-power battery-operated devices, portable equipment, data acquisition equipment, test equipment, and low-end audio applications.  This device is also AEC-Q100 Grade 1 qualified for automotive applications.

Maxim’s MAX6106 is a low-cost LDO (low-dropout), micropower voltage reference. This three-terminal reference has an output voltage of 2.048 V. The LDO features a proprietary curvature-correction circuit and laser-trimmed, thin-film resistors that result in a low temperature coefficient of 75 ppm/°C (maximum) and an initial accuracy of ±0.4% (maximum). It is offered in the extended temperature range (-40°C to +85°C); it only draws 90 µA of supply current and can source 5 mA and sink 2 mA of load current.