Nowadays, smart speakers are very common in our lives. They are a tool for people to surf the Internet. They can also play songs on demand, shop online, and forecast weather. They can also turn on lights, turn on TV, turn on curtains, set the temperature of the refrigerator, and heat up the water heater. Smart speakers are a very smart home product with a very broad market prospect in the future.

What parts are common smart speakers made of? What role do diodes and triodes play in smart speakers? How do they help smart speakers achieve more intelligent functions. In this issue, Heketai will introduce you to the application of diode and triode in smart speakers to help you better understand the role of diode and triode products in smart speakers.

As we all know, diode is one of the most basic components in electronic products. Generally, electronic products will use diodes to reasonably connect elements and components such as resistors, capacitors, inductors, etc. to form circuits with different functions, which can realize various functions such as alternating current rectification, modulation signal detection, amplitude limiting and clamping, and power supply voltage stabilization.

A common smart speaker usually includes several modules: microprocessor, audio processing circuit module, power management circuit module, interface circuit module, LED display circuit module, data storage circuit module, etc. The BOM usually includes SoC chip, mixed signal microcontroller, WiFi/Bluetooth single chip, stereo audio amplifier chip, voice specific chip, DSP chip, memory chip, power management chip, LED driver, MEMS microphone polar array, PCB board, diode, triode, resistance, capacitance, inductance, crystal oscillator, sensor, connector, speaker, micro button, microphone, battery, USB interface, etc.

Take the common echo cancellation circuit as an example, diode products will be used in this part. The accuracy challenge of intelligent speaker speech recognition is that the microphone will pick up the ambient noise. To filter the noise, one technology is echo cancellation, which can recognize the digital signal of music playing, and then remove the signal from the microphone input. In order to better filter out the ambient noise, the audio amplifier with echo cancellation function has an SDOUT signal, and then the SDOUT signal is fed into the SoC to filter out the music signal received by the microphone.

Take the audio output module for example. The audio source module of the smart speaker is usually divided into two parts, one is the digital part responsible for outputting digital signals, and the other is the decoding part responsible for digital/analog conversion of digital signals. The power amplifier is also divided into a pre amplifier and a post amplifier. The pre amplifier is mainly responsible for signal voltage amplification, volume control, switching of multiple sound sources, tone adjustment, impedance matching and other functions, while the post amplifier is specifically responsible for power amplification. Both parts will use diode and triode products.

The purpose of power amplifier is to provide enough current driving capacity for the load to realize power amplification. Class D power amplifier is also called digital amplifier. It uses the conversion switch circuit of extremely high frequency to amplify the audio signal, which has the advantages of high efficiency and small size. The typical topology of Class D power amplifier is composed of triangle wave generator, comparator, power output stage and LC low-pass filter. In the full duplex voice interaction system of smart speakers, the quality of power amplifiers is very important, because AEC echo cancellation is very sensitive to signal distortion, and the performance of diodes has a great impact on power amplifiers.

In addition to the above examples, the diode and triode are used in boost switching power supply circuit, over-current protection circuit, over-voltage protection circuit, rectification circuit, detection circuit, etc. of smart speakers. Heketai products are widely used in smart speakers, mainly providing products and services such as bridge stack, diode and triode for smart speakers. The popular diode models include 1N4148, 1N4148, M1, etc. The triode models include S8050, S8550, MMBT3904, MMBT3906, etc.

Although the smart speaker market has a very good future, the industry has been affected by the epidemic situation and external factors in recent years. The overall sales growth of smart speakers has slowed down. Against the background of sluggish consumer demand, the smart speaker industry has entered a bottleneck period of growth. For solution providers, it is particularly important to provide brands with more cost-effective and competitive products and solutions.

Today's smart speaker industry is more competitive than ever before. In addition to developing products with better quality, more powerful functions, and more convenient use, brand makers also have an important choice of suppliers, including reviewing their product development, manufacturing, and supply capabilities. In order to take the lead in the fierce market competition, the design of smart speakers needs to consider the system cost, product stability and structural appearance. Heketai integrates R&D, packaging, testing and production, which can help smart speakers improve energy efficiency, reduce energy consumption and enhance the market competitiveness of customers' products.

Heketai has more than 30 years of experience in diode and triode manufacturing, and can provide smart speaker customers with product lines including power management, bridge stack, diode, triode, MOSFET, etc., to provide customers with application solutions and on-site technical support services. It has accumulated rich core technologies in circuit design, semiconductor device and process design, reliability design, device model extraction, etc., and has obtained national invention patents, utility model patents and other qualifications