openQCM NEXT
A Network Analyzer QCM shield
As for the Q-1 the openQCM NEXT electronics mainly consists of a network analyzer that passively interrogates the quartz sensor by sweeping around its resonance frequency.
The actuation signal is generated using the AD9851 DDS/DAC frequency synthesizer and the output signal is read by AD8302 gain and phase detector, which can measure both the magnitude ratio (gain) across the quartz crystal and the phase difference between the actuation and output signals. The analysis of the gain curve allows the characterization of the sensor by measuring simultaneously the resonance frequency and quality factor. The main advantage of the scheme of measurement is the possibility to measure quartz sensor parameters in isolation without external circuity influences.NEXT
Teensy 4.0 inside its heart
openQCM Q-1 is controlled by the powerful Teensy 4.0 (developed by Paul Stoffregen) , that mounts a ARM CortexM7 brings many powerful CPU features to a true real-time microcontroller platform. So, CPU performance is many times faster than typical 32 bit microcontrollers. The high clock speed drastically increase the ADC sampling time and the resolution of the measurements.
ACTIVE THERMAL CONTROL
Onboard the main electronics is mounted a miniaturised, safe and very high accuracy complete Peltier single-module controller: MTD415 (by Thorlabs). The MTD415T is a compact and highly integrated temperature controller optimized for use in high performance thermoelectric temperature control applications. The on-chip power stage and the thermal control loop circuitry minimize external components while maintaining high efficiency.
The output current is directly controlled to eliminate current surges. An adjustable TEC current limit provides the highest level of TEC protection. The MTD415T is operated from a single power supply and provides a bipolar ±1.5 A output by connecting the TEC to the output of a bipolar
power stage. True bipolar operation ensures temperature control without “dead zones” or other non linearities at low TEC current values. These TEC controllers deliver powers up to 6 W and a maximum TEC current of ±1.5 A.
The TEC controller supports a 10 kΩ thermistor, integrated in the Sensor Module of openQCM NEXT.
