情境
An embedded system designer needs to integrate a Quectel L76K GNSS module with an active patch antenna. The circuit requires stable 3.3V power, a bias-T to feed DC to the antenna LNA, and decoupling to ensure clean RF reception.
這張圖裡有什麼
看懂背後的決策。
01
Use an inductor (L1) and capacitor (C2) to form a bias-T network, injecting DC onto the antenna line while blocking DC from the receiver input.
02
Add decoupling capacitors on both main VCC and VCC_RF pins for noise suppression.
03
Pull-up resistors on TXD/RXD lines ensure idle high levels when UART is unconnected.
Suitable for any project using active GNSS antennas with integrated LNA, where the receiver module provides a bias output (VCC_RF) or when an external bias supply is needed.