The spectrum of wireless communication is limited, the distribution is very strict, and the electromagnetic wave of the same bandwidth can only be used once. In order to solve the problem of many problems, engineers have developed a number of "modulation technology" (ModulaTIon) and "multi-tasking technology" (MulTIplex) to increase Spectrum efficiency, so the invention of 3G, 4G, 5G different communication generation technology, then what components in our mobile phone are responsible for handling these technologies for us? Modulation technology and multitasking technology First of all, we need to understand that ModulaTIon is completely different from Multi-tasking (MulTIplex). Let's first look at how they differ. Digital signal modulation technology (ASK, FSK, PSK, QAM): Transform the simulated electromagnetic waves into different waveforms to represent 0 and 1 different digital signals. ASK uses amplitude to represent 0 and 1, FSK uses frequency to represent 0 and 1, PSK uses phase (waveform) to represent 0 and 1, QAM uses both amplitude magnitude and phase (waveform) to represent 0 and 1. Well, the digital signals 0 and 1 that each person's mobile phone antenna is going to transmit become electromagnetic waves of different waveforms. The problem is coming again. So many different waveforms of electromagnetic waves are thrown into the air, how to distinguish those that are yours (and What are you talking about, those are my (and I am talking)? Multitasking technology (TDMA, FDMA, CDMA, OFDM): Differentiating electromagnetic waves to different users. TDMA uses time to distinguish between yours and me. FDMA uses different frequencies to distinguish between yours and me. CDMA uses different passwords (orthogonal spreading codes) to distinguish between yours and me. OFDM uses different positives. The subcarrier frequency is used to distinguish between yours and mine. It is worth noting that digital signal modulation technology or multi-tasking technology is performed together when digital signals (0 and 1) are processed and processed. Generally, multi-tasking technology is first performed and then digital signal modulation technology is performed. (except OFDM), so multitasking technology and modulation technology must be used at the same time. Digital modulation technology (Digital modulation) The current mobile phone belongs to "digital communication", that is, the voice of our speech (continuous analog signal), which is first converted into discontinuous 0 and 1 digital signals by the mobile phone, and then converted into electromagnetic waves by digital modulation (analog signal) Carrying the digital signal), and finally transmitting it from the antenna, the principle is shown in Figure 1. â–² Figure 1: Schematic diagram of digital communication. (Source:the Noun Project) Digital communication system architecture The architecture of the digital communication system is shown in Figure 2 (a). Users may use a smartphone to make a voice call or access the Internet for data communication. We explain the following: â–² Figure 2: Schematic diagram of the communication system architecture. Voice upload (speaking phone): After the sound is received by the microphone, it is a low-frequency analog signal, which is converted into a digital signal by a low-frequency analog-to-digital converter (ADC), and is subjected to data compression (Encoding) and cyclic repetition through a "baseband chip (BB)". Check code (CRC), channel coding, interleaving (Inter- Leaving, Ciphering, Formatting, and multi-signaling, Modulation, and other digital signal processing, as shown in Figure 2(b). Next, it is converted into a high-frequency analog signal (electromagnetic wave) via an "IF chip" (IF), that is, a high-frequency digital-to-analog converter (DAC); finally, an electromagnetic wave of different time, frequency, and waveform is formed via a "radio frequency chip (RF)". It is transmitted by the antenna. Voice download (listening to the phone): The antenna receives electromagnetic waves of different time, frequency and waveform, and obtains high-frequency analog signals (electromagnetic waves) through "radio frequency chip (RF) processing, and then via "IF chip" (IF) The high frequency analog to digital converter (ADC) is converted to a digital signal. Next, de-modulation, de-multiplexing, de-formatting, de-ciphering, and de-interleaving (De-) are performed via "baseband chip (BB)". Inter-leaving, channel decoding, CRC, data decoding, etc., and finally converted to low-frequency analog signals via a low-frequency digital-to-analog converter (DAC) Sound) is played out by the microphone. Data communication (online): Basically, data communication is digital signal regardless of uploading or downloading, so it can be directly processed into the baseband chip (BB). Other processes are similar to voice communication, and will not be repeated here. Note: The principle of communication is a lot of mathematics. Since the mobile phone is something we use every day, most people are curious about the feeling of communication and want to know more, but often go into the first class of the classroom to see It is a lot of complicated digital: Fourier Transform, Laplace Transform, Discrete, and immediately retreat. In order to simplify the complexity, it is easy for everyone to understand. The above is for digital communication systems. The introduction is just a gesture, and there will be a gap with the actual situation. It is recommended that those who are interested in further understanding can base on the above concepts to further understand the technical details. Wireless communication system architecture Based on the previous introduction, let's take a look at several important integrated circuits (ICs) in the smartphone, including: baseband (BB), intermediate frequency (IF), and radio frequency (RF), as shown in Figure 3. Each part may have one to several integrated circuits (ICs), or it may be a package of several integrated circuits (ICs), called "System in a Package (SiP)", or The chips are integrated into one, called "System on a Chip (SoC)". â–² Figure 3: Schematic diagram of the wireless communication system architecture. Baseband (BB): A digital integrated circuit for digital signal compression/decompression, channel encoding/decoding, interleaving/de-interlacing, encryption/decryption, formatting/deformatting, multitasking/ Solving multitasking, modulation/demodulation, and managing communication protocols, controlling input and output interfaces, etc., famous mobile phone baseband chip suppliers include: Qualcomm, Broadcom, Marvell , MediaTek, etc. Modulator: Convert the digital signal processed by the baseband chip into a high-frequency analog signal (electromagnetic wave), which can be transmitted very far. For those who want to know more about the communication principle, please refer to it here. Mixer: Mainly responsible for the frequency conversion work, converting the modulated high frequency analog signal (electromagnetic wave) into the required frequency to match the frequency range (wireless spectrum) of different communication systems. Synthesizer: Provides the operating frequency required for wireless communication electromagnetic waves and radio frequency integrated circuits (RF ICs), usually via "Phase Locked Loop (PLL) and "Voltage Controlled Oscillator" (VCO: Voltage Controlled Oscillator) ) to provide accurate working frequency. Band Pass Filter (BPF): Only high-frequency analog signals (electromagnetic waves) in a specific frequency range (band) pass through, filtering out unwanted frequency ranges to obtain the frequency range (band) we need. Power Amplifier (PA): Before the high-frequency analog signal (electromagnetic wave) is transmitted, it must be amplified by a power amplifier (PA) to enhance the signal to be transmitted far enough. Transceiver: Transmitted (Tx:Transmitter) high-frequency analog signal (electromagnetic wave) to the antenna, or received by the antenna (Rx: Receiver) high-frequency analog signal (electromagnetic wave). Low Noise Amplifier (LNA): When receiving a signal, the high-frequency analog signal (electromagnetic wave) received by the antenna is very weak. It must be amplified by a low-noise amplifier (LNA) before it can be processed. Demodulator (Demodulator): used to receive signals, convert high-frequency analog signals (electromagnetic waves) into digital signals, and then transmit them to the baseband chip (BB) for digital signal processing. Therefore, the principle of mobile phone uploading (talking phone) is: firstly, the digital voice signal is processed by the baseband chip (BB), and then converted into a high frequency analog signal by a modulator, and converted into a desired one by a mixer (Mixer). Frequency, a high-frequency analog signal (electromagnetic wave) of a specific frequency range (band) is obtained by a band pass filter (BPF), which is enhanced by a power amplifier (PA) and finally transmitted by a transmission receiver (Tx) to an antenna output. On the contrary, the principle of mobile phone download (listening to the phone) is: firstly, the high-frequency analog signal (electromagnetic wave) is transmitted by the antenna, received by the transmitting receiver (Rx), and then obtained through a band pass filter (BPF) to obtain a specific frequency range ( The high frequency analog signal of the frequency band is amplified by a low noise amplifier (LNA), converted into a desired frequency by a mixer (Mixer), converted into a digital voice signal by a demodulator (Demodulator), and finally The baseband chip (BB) processes the digital voice signal. Communication related integrated circuits: baseband, intermediate frequency, radio frequency The back end of the wireless communication system described above uses a baseband chip to process digital signals, and the integrated circuit (IC) used in the front end can be roughly divided into two types: "RF chip" and "IF chip". Classes, fabricated using wafers of different materials: Intermediate Frequency (IF): Also known as "Analog baseband", the concept is "high-frequency digital-to-analog converter (DAC)" and "high-frequency analog-to-digital converter (ADC)", including: Modulators, demodulators, and usually IF amplifiers and intermediate bandpass filters (IF BPFs), usually composed of CMOS components made of silicon wafers, possibly several Integrated circuits, some of which may be integrated into an integrated circuit (IC). Radio Frequency (RF): Also known as Radio Frequency Integrated Circuit (RFIC), it is a general term for all chips that process high-frequency wireless signals, usually including: Transceiver, Low Noise Amplifier (LNA), Power Amplifiers (PAs), Bandpass Filters (BPFs), Synthesizers, Mixers, etc., typically MEMSFETs fabricated from gallium arsenide wafers, HEMT components, or BiCMOS components fabricated from silicon germanium wafers Or a CMOS component made of silicon wafers. Currently, a power amplifier made of gallium nitride (GaN) may be used, which may be several integrated circuits, some of which may be integrated into one integrated circuit (IC). Pure Sine Wave,Single Phase Hybrid Inverter,3 Phase Hybrid Inverter,Split Phase Hybrid Inveter Easun Power Technology Corp Limited , https://www.epinverter.com
