Reference circuitry

This section contains a configuration summary, a schematic, and bill of materials table for QDAA QFN40 circuit configuration number 1.

Figure 1. Circuit configuration no. 1 schematic for QDAA QFN40

This section contains a configuration summary, a schematic, and bill of materials table for QDAA QFN40 circuit configuration number 2.

Figure 2. Circuit configuration no. 2 schematic for QDAA QFN40

This section contains a configuration summary, a schematic, and bill of materials table for QDAA QFN40 circuit configuration number 3.

Figure 3. Circuit configuration no. 3 schematic for QDAA QFN40

This section contains a configuration summary, a schematic, and bill of materials table for QDAA QFN40 circuit configuration number 4.

Figure 4. Circuit configuration no. 4 schematic for QDAA QFN40

This section contains a configuration summary, a schematic, and bill of materials table for CFAA WLCSP circuit configuration number 1.

Figure 5. Circuit configuration no. 1 schematic for CFAA WLCSP

This section contains a configuration summary, a schematic, and bill of materials table for CFAA WLCSP circuit configuration number 2.

Figure 6. Circuit configuration no. 2 schematic for QFAA WLCSP

This section contains a configuration summary, a schematic, and bill of materials table for CFAA WLCSP circuit configuration number 3.

Figure 7. Circuit configuration no. 3 schematic for CFAA WLCSP

This section contains a configuration summary, a schematic, and bill of materials table for CFAA WLCSP circuit configuration number 4.

Figure 8. Circuit configuration no. 4 schematic for CFAA WLCSP

A well designed PCB is necessary to achieve good RF performance. Poor layout can lead to loss in performance or functionality.

A qualified RF layout for the device and its surrounding components, including matching networks, can be downloaded from www.nordicsemi.com.

To ensure optimal performance it is essential that you follow the schematics and layout references closely. Especially in the case of the antenna matching circuitry (components between device pin ANT and the antenna), any changes to the layout can change the behavior, resulting in degradation of RF performance or a need to change component values. All reference circuits are designed for use with a 50 Ω single-ended antenna.

A PCB with a minimum of four layers, including a ground plane, is recommended for optimal performance. On the inner layers, put a keep-out area on the inner layers directly below the antenna matching circuitry (components between device pin ANT and the antenna) to reduce the stray capacitances that influence RF performance.

A matching network is needed between the RF pin ANT and the antenna, to match the antenna impedance (normally 50 Ω) to the optimum RF load impedance for the chip. For optimum performance, the impedance for the matching network should be set as described in the recommended package reference circuitry in Reference circuitry.

The DC supply voltage should be decoupled as close as possible to the VDD pins with high performance RF capacitors. See the schematics for recommended decoupling capacitor values. The supply voltage for the chip should be filtered and routed separately from the supply voltages of any digital circuitry.

Long power supply lines on the PCB should be avoided. All device grounds, VDD connections, and VDD bypass capacitors must be connected as close as possible to the device. For a PCB with a topside RF ground plane, the VSS pins should be connected directly to the ground plane. For a PCB with a bottom ground plane, the best technique is to have via holes as close as possible to the VSS pads. A minimum of one via hole should be used for each VSS pin.

Fast switching digital signals should not be routed close to the crystal or the power supply lines. Capacitive loading of fast switching digital output lines should be minimized in order to avoid radio interference.

The PCB layout shown in the following figures is a reference layout for the QFN package with internal LDO setup and VBUS supply.

For all available reference layouts, see the product page for the nRF52820 on www.nordicsemi.com.

Figure 9. Top silk layer

Figure 10. Top layer

Figure 11. Mid layer 1

Figure 12. Mid layer 2

Figure 13. Bottom layer

The nRF52 Series is comprehensively supported by Nordic Semiconductor's own range of PMICs (Power Management Integrated Circuits). These PMICs are meticulously designed to enhance the performance and efficiency of the nRF52 Series devices. This integration ensures the longest battery life and the highest reliability for the end application. The synergy between the nRF52 Series and the Nordic PMICs highlights Nordic Semiconductor's commitment to providing a complete and cohesive solution for their customers' needs in wireless technology applications.