AN4148 Datasheet, PDF (5/13 Pages) STMicroelectronics – Using the SPIRIT1 transceiver under ARIB STD-T93 in the 315 MHz band

AN4148
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Application circuit
Application circuit
Figure 1 shows an image of the SPIRIT1 application board. The application is made up of 2
boards: a daughterboard and a motherboard. The daughterboard contains the SPIRIT1 with
the circuits necessary for it to work. For correctly functionality, the daughterboard must be
plugged into the motherboard (see Figure 2) by two header 5x2 connectors (J6 and J7).
The motherboard is provided with an STM32L152VBT6 microcontroller to correctly program
the transceiver. The microcontroller is programmed with firmware developed for the SPIRIT1
application. A graphical user interface (GUI) is developed to correctly program the SPIRIT1.
The daughterboard is provided with a 52 MHz XTAL to provide the correct oscillator to the
SPIRIT1.
The SPIRIT1 has an internal SMPS that drastically reduces power consumption, making it
the best-in-class for application on this bandwidth. The SMPS is fed from the battery (1.8 V
to 3.6 V) and provides the device with a programmable voltage (1.4 V typical). An SMA
connector is present to connect the board to an antenna or to instrumentation to verify the
correct functionality and verify the ETSI standard request.
A few of passive devices (inductors and capacitors) are used for matching/filtering in the
power amplifier (PA) and balun network for the receiver.
To reduce application costs, the SPIRIT1 is designed to work without an external antenna
switch. The daughterboard is designed to show the SPIRIT1 functionality in this condition.
Clearly, an application with antenna switch can be realized, but this is not described in this
document.
Figure 1. SPIRIT1 application daughterboard
Doc ID 023517 Rev 1
AM13146v1
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