web
openqcm.com
Centro Direzionale, Isola G7
80143 Naples (Italy)
phone +39 081 0320584
5
Electronic Hardware
Teensy
The openQCM Q-1 PCB is designed to use a Teensy 3.6 development board
https://www.pjrc.com/teensy/index.html
which is a powerful arduino-compatible microcontroller, featuring a 32 bit 180 MHz ARM Cortex-M4
processor developed by Paul Stoffregen. The development board has a lot of functionalities, the most
interesting one is the analog input ADC with an usable resolution of 13 bits
https://www.pjrc.com/teensy/techspecs.html
It means that over the full-scale range of 3.3 volt it is possible to measure input voltage variations with a
resolution 0.4 mV/bits.
Frequency Synthesizer AD9851 DDS/DAC
The AD9851 DDS/DAC frequency synthesizers
http://www.analog.com/media/en/technical-documentation/data-sheets/AD9851.pdf
is an integrated device which uses DDS technology for generating an analog output sine wave when it is
referenced to a stable clock source. In this application the AD9851 was connected to a 30MHz standard
clock oscillators. The DDS can generate a sine wave with frequency from DC up to 72 MHz, with an
output tuning resolution of about 0.04 Hz when clocked at 180 MHz. The output frequency is controlled
by the digital pin W_CLK and S_LD using a defined protocol of communication.
The wide
–
range frequency output capability of AD9851 ( 0
–
72 MHz) enables to interrogate the quartz
sensor not only at the fundamental frequency but also to the higher mode of vibration, which are
supposed to be more suitable for biosensing applications, mainly because they have less drift and less
environmental effects.
Gain and Phase Detector AD8302
The AD8302 Gain and Phase Detector
www.analog.com/media/en/technical-documentation/data-sheets/AD8302.pdf
is capable of measure simultaneously both the magnitude ratio, defined as gain, and phase
difference
between two signals, from low frequencies up to 2.7 GHz. The AD8302 measures the gain loss through
the quartz crystal, referenced to the input signal, and simultaneously the phase lag between the
response and actuation signal.