Recently, I watched a detailed explanation of circuit design by Philip Salmony, a graduate student from Cambridge University, on YouTube. The project is called the STM32-based RF to USB adapter, abbreviated as STRF, which includes:
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High-speed USB interface
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STM32L4 as the controller
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nRF24 2.4GHz RF transceiver
Of course, he designed it using KiCad, and his circuit is shown in the image below:
This board is relatively simple but is a typical type of mixed circuit. Most circuits will include three parts – USB, 32-bit microcontroller/FPGA, and analog/RF circuits (like our simple DDS signal generator).
First Part
Second Part
This guy’s video explanation is fantastic; in just over 40 minutes, he clearly outlines the key points of circuit and PCB design – covering both comprehensive system design introductions and some detailed introductions to key circuits, such as high-speed digital design, RF layout/wiring considerations, and he also discusses some key points in schematic design using KiCad, such as why a 10uF capacitor should be used for the 3.3V regulator – to limit the surge current on the USB’s 5V voltage.
In the layout and wiring section, he introduces component layout, wiring strategies, how to design impedance-matching trace widths, RF design’s 4-layer stack-up strategies, and how to handle the ground under the crystal and the RF circuit section.
Although he designed it using KiCad, the design points are equally applicable to any PCB design tool.
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