Overview

LF RFID reader built around an STM32H7. The antenna is driven by a 600 V MOSFET bridge with dedicated gate drivers; the reply signal goes through instrumentation amplifiers, filters and VGAs before digitization. Field interfaces are transient-protected and switching is isolated with solid-state relays.

Design challenges solved

1. Antenna power stage: twelve 600 V MOSFETs with gate drivers and an input boost converter.
2. Weak-signal receive: INA821, OPA192 and AD8338 VGAs with a precision voltage reference.
3. 6-layer domain separation: high voltage, sensitive analog and fast digital.