Bluetooth PCB: Enablers of Wireless Technology

Bluetooth technology has a history of over 20 years in electronic applications. As this technology continues to evolve, it has expanded its reach beyond communication systems to deeply integrate with various aspects of human activities. This includes products related to smart buildings, intelligent industries, and smart cities, among others. In order to harness the power of wireless connectivity and data transmission, engineers are embedding Bluetooth modules into PCB designs. In this article, FS Technology will comprehensively explore Bluetooth PCB to assist you in achieving your deployment requirements.

bluetooth circuit board

Understanding Bluetooth PCB

In the earlier stages of wireless connectivity, infrared technology was employed. However, due to its inability to support simultaneous connections from multiple signal sources to a network and its strong dependence on sensor environments, it gradually gave way to Bluetooth technology. Bluetooth utilizes radio frequency signals to facilitate information sharing between accessing devices. Operating within the 2.4 GHz ISM frequency band, Bluetooth typically achieves signal connection distances of up to 100 meters or even farther, accommodating connections with dozens of peripheral devices simultaneously. With advancements in technology, apart from classic Bluetooth, Low Energy Bluetooth (BLE), which conserves energy consumption when no data transfer is occurring, and Bluetooth 5, offering enhanced speed and power features, have emerged.

Taking the widely-used CSR Bluetooth module 86XX series as an example, the circuit board is equipped with four pins responsible for functions like status, enablement, communication, and power. These functionalities rely on various components, such as Bluetooth SoCs, clock crystals, antennas, SMPS power inductors, filter capacitors, and memory chips, interconnected on the board. For signal transmission between disconnected devices, these electronic devices are equipped with surface-mounted antennas that receive signals and transmit them to the mainboard for processing and output. The operation of a Bluetooth PCB can be understood through three levels: the master-slave relationship, the transmission process, and data transfer.

Bluetooth Communication’s Master-Slave Relationship:

  • Within communication devices, one side acts as the host, while the other functions as the slave.
  • When enabling Bluetooth communication, both roles must be explicitly defined, initiating the host to initiate a search operation.
  • A single connection can support up to 7 devices simultaneously.
  • The roles aren’t permanent; typically, the initiator of the signal becomes the primary role.

Bluetooth Communication Process:

  • Two matched devices require pairing using a PIN code.
  • The slave device needs to obtain trust information from the master device to ensure a secure connection.
  • After successful pairing, both devices have the capability to initiate connection establishment requests.
  • Either device can initiate a request to disconnect.

Data Transfer:

  • Devices come with two pairing states:
  • Slave device silent state: Can only communicate with the master device and remains undetectable by other devices.
  • Slave device discoverable state: Can be detected by the master device and establish connections with other devices.

Electronics with Bluetooth PCB Board

Multimedia Transfer

Equipping devices with Bluetooth capabilities in multimedia applications allows them to access audio and video data sources. For instance, your smartphone includes a Bluetooth-enabled PCBA, enabling you to play songs and videos and transmit them to other Bluetooth devices. Bluetooth headphones are commonly used for audio and voice signal transmission. The functional board facilitates audio signal transmission to the headphones, operating as follows:

  1. The decoding chip decodes audio files, generating digital signals of 0s and 1s, which are then sent to the headphones via the Bluetooth antenna.
  2. Upon receiving the digital signal, an internal digital-to-analog conversion chip transforms it into audio.
  3. The analog signal is amplified through an amplifier.
  4. Bluetooth headphones receive and amplify the signal, producing sound output.

Computer Peripherals

While laptops are widely used and offer excellent performance, they can sometimes fall short in terms of user experience when compared to desktop computers. To address this, adding a mouse and keyboard to laptops is common. However, for some frequent users, wireless options may not be ideal due to the subtle latency introduced by different connectivity methods:

Connectivity Methods:

  • Bluetooth Keyboard: Keyboard PCB uses Bluetooth transmission protocol for data transfer, enabling Bluetooth communication within an effective range (within 10 meters).
  • Wireless Keyboard: Transmits signals to specific electronic devices using infrared technology or radio waves.

Reception Methods:

  • Bluetooth Keyboard: Receives and sends signals through internally installed antennas. Ceramic antennas can be used as an alternative to address transmission latency. Further reading: Ceramic Chip Antenna vs. PCB Antenna
  • Wireless Keyboard: Receives signals through an externally installed receiver on the device.

Bluetooth Speakers

Bluetooth speakers have extensive applications in consumer electronics, especially in home-use devices. They utilize a PCBA board with integrated Bluetooth modules as the main control unit, enabling wireless connectivity and eliminating the need for complex wire connections. Their operation is user-friendly and similar to that of Bluetooth on mobile phones.

Key Components and Functions:

  • Main Control PCBA Board: Responsible for controlling all operations of the speaker, including data transmission, connection, and communication with other devices.
  • Audio Amplifier: Amplifies audio signals to drive the speaker and produce sound.
  • Voltage Regulator: Ensures stable power voltage for the speaker circuit, ensuring consistent and stable audio quality.
  • Charger: Some Bluetooth speakers come with charging functionality, and the charger module is responsible for recharging the built-in battery.
  • Control Buttons: One side of the main board includes volume control buttons, power switch button, and microphone for activating voice calls.
  • Speaker: The speaker is a crucial component that generates sound by converting audio signals into audible sound.
  • Battery: Some Bluetooth speakers have built-in batteries to ensure they can operate without external power source.

Bluetooth Modules

A straightforward technique for incorporating Bluetooth functionality into devices is by employing Bluetooth modules, which are integrated circuits encompassing Bluetooth capabilities. These modules are installed onto PCBA boards. Broadly categorized by their functions, they fall into three classes: data modules, audio modules, and combined audio + data modules. Utilizing single-chip Bluetooth systems and CMOS technology, these modules measure 12.7 millimeters by 27 millimeters and operate at a data transmission rate of 2.4 GHz, with a maximum speed of 3 Mbps, supporting Bluetooth 2.0.

For clients, the utilization of Bluetooth modules offers the following advantages:

  • Faster realization of Bluetooth PCB design and reduced certification costs.
  • While slightly costlier, these modules yield economies of scale.
  • Aids in enhancing the functionality of the serial interface through wireless communication.
  • PCBA boards with built-in Bluetooth modules can harmonize with PC-associated hardware.
  • Equipped with USB ports for direct connection to various systems.

Bluetooth Transmitter PCB

Bluetooth signal transmission facilitates the connection of electronic products lacking Bluetooth functionality to Bluetooth networks. By installing Bluetooth transmitter PCB on devices like desktop computers and televisions, these devices can be transformed into products with Bluetooth capabilities. In typical applications, these boards can receive audio signals from external sources such as smartphones, enabling audio transmission, as well as data from sensors. They typically rely on an external power source to ensure a stable operational state. In some cases, consideration may be given to using built-in lithium-ion batteries for a certain period of wireless operation. To ensure continuous power supply, some designs also incorporate charging systems to recharge the batteries when needed.

Primarily consist of the following three core components:

  • Sensor Data Processing Unit: Responsible for collecting and processing data from various sensors, including environmental parameters and location information. This data is then encoded and transmitted to other devices.
  • Power Management and Voltage Regulation System: Provides stable power voltage to ensure proper power supply to various circuit components.
  • Bluetooth Communication Module: Integrates the Bluetooth wireless communication protocol, responsible for encoding sensor data and transmitting it to other Bluetooth devices through Bluetooth signals.

Bluetooth Receiver PCB

Receivers are employed to retrieve signals from devices that support Bluetooth and transmit these signals to other modules. Each device’s circuit includes a Bluetooth reception system to manage operations. Rechargeable batteries used for continuous operation need periodic replacement. In certain devices, the use of lithium-ion batteries can extend the usage time per single charge. Batteries are incorporated on the board to prevent overcharging and discharging.

The PCB of a Bluetooth receiver is equipped with an antenna to receive signals from phones or other Bluetooth devices. Its structure resembles that of a Bluetooth speaker circuit and is equipped with integrated circuits. To handle the amplifier system, the board is also configured with auxiliary outputs. Amplifiers and voltage regulators are installed on the board to ensure optimal operation.

For enthusiasts, these components can be purchased from electronics stores. If you need bulk component procurement services, FS Technology is very willing to help. Moreover, utilizing a professional Bluetooth PCB manufacturer is a prudent choice to avoid issues like functionality gaps.

Bluetooth PCB FAQ

This problem may arise due to various factors such as distance, interference, battery status, and PCB layout. In circuit design, it is recommended to optimize antenna design and utilize ground planes along with signal layer isolation to mitigate the impact of electromagnetic interference.

Select Bluetooth Module→Circuit Design→Antenna Design→Power Management→Impedance Matching→Layer Stacking→Ground Plane Layer→Pad Design→Bare Board Manufacturing→Component Assembly→Functional Test

Indeed, FS Tech provides PCBA manufacturing services for the consumer electronics industry, encompassing a wide range of products such as computers, mobile phones, gaming consoles, and various Bluetooth peripheral devices.

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