China Zhongshi Zhihui Technology (suzhou) Co., Ltd. Company News

   The stability of the amplifier in a circuit is determined by the noise gain, not the signal gain. Most modern op amps are stable at unity gain, but some special purpose amplifiers cannot do this. Compared to standard unity-gain stabilized op amps, non-fully compensated op amps provide unique advantages, such as lower noise voltages and wider bandwidth. So, in which case should noise gain be dealt with?    Imposing noise gain can bring benefits to a variety of applications. For example, to take advantage of one or more characteristics, you may need to use a non-fully compensated amplifier below its minimum stable gain. Normally it will not work, but handling the noise gain can "fool" the amplifier into thinking it is operating at a higher gain. Another wonderful benefit of imposing high noise gain is that it improves the stability of the amplifier when driving capacitive loads.    Depending on the situation, imposing noise gain usually requires adding a resistor or a capacitor to the circuit. It may be as simple as adding a resistor between the inverting and non-inverting inputs, adding a series RC circuit between the inverting input and ground, or connecting the component in parallel with the input or gain resistor.

The circuit principle of RF power amplifier is that the directional coupler at the output end of the transmitter power amplifier detects the reverse power voltage output. After being processed by the relevant circuits in the power amplifier stabilizing power supply, it is sent to the transmitter control circuit XP1/12A. Then, after passing through the reverse power detection voltage compensation circuit, it is added to the N20B amplifier, which is then added to the in-phase input terminal of N20A. When the voltage at this input terminal reaches about 300mV (when the power amplifier output and antenna impedance are mismatched, the voltage standing wave ratio is greater than 2.5:1), the output voltage of N23A is greater than 6.2V, causing the VD5 voltage regulator and V3 to conduct. V3 conduction causes VD6 conduction, which lowers the level of the in-phase input terminal of N23B and the voltage at the output terminal of N23B. As a result, the DC control voltage applied to the Vx input terminal of the analog multiplier N24 drops to a certain level, ultimately reducing the output power of the RF amplifier to a certain value and protecting the RF amplifier. When the voltage standing wave ratio is not greater than 2.5:1, the reverse power detection voltage is small, and the voltage output by N23A is not enough to make VD5 conductive. Therefore, the circuit VD6 of the RF power amplifier is also turned off due to reverse bias. Only the normal power DC control voltage set on the front panel is applied to the N23B in-phase input terminal, and the voltage applied to the input terminal of the analog multiplier Vx is also normal. The transmitter RF power amplifier outputs power normally.

In the era of information, the influence of automatic identification technology is even more important today. As the ancestor of automatic identification, bar code technology has long been unable to cope with the rapid demand for information automation today. As a novel information technology, RF power amplifier technology has emerged, fully leveraging the technical advantages of automatic identification. In practical applications, UHF(915MHz) radio frequency identification technology is sensitive to water-containing substances and cannot be used in humid environments. This is because the UHF signal has a high frequency and short wavelength, and is easily absorbed by substances with a large water content, resulting in energy weakening and a sharp decline in performance. However, long-distance HF(13.56MHz) radio frequency identification signals have low frequencies and long wavelengths. Therefore, the design of RF power amplifier modules has become the most important aspect of the development of RF communications.

The operating frequency of RF power amplifiers is very high, but the relative frequency band is narrow. RF power amplifiers generally use frequency selection networks as the load loop. RF power amplifiers can be divided into three types of working states: A (A), B (B), and C (C) according to different current conduction angles. The conduction angle of the current of the Class A amplifier is 360°, which is suitable for small signal and low power amplification. The conduction angle of the current of the Class B amplifier is equal to 180°, and the conduction angle of the current of the Class C amplifier is less than 180°. Both Class B and Class C are suitable for high-power working states, and the output power and efficiency of Class C working state are the highest among the three working states. Most RF power amplifiers work in Class C, but the current waveform of Class C amplifiers is too distorted and can only be used for resonant power amplification using a tuned loop as a load. Because the tuning loop has filtering capabilities, the loop current and voltage are still close to sinusoidal waveforms, with little distortion.  

The integration of baseband chips and radio frequency chips has always been a topic in the mobile phone industry. However, the integration of baseband chips and RF chips is not a topic that is really in demand at present. Silicon Laboratories has achieved a single chip design in the industry, but it has not become very popular in the market, but has been acquired. Many foreign RF professional manufacturers still have a large share of mobile phone platforms."Therefore, although the topic of full integration and integration of RF chips and baseband chips will continue to exist, there will be no real motivation to carry out this investment in the next three years." The technical person in charge of Dingxin Company said. However, from the perspective of future development trends, it is an inevitable trend to achieve more integration of TD-SCDMA radio frequency module chips and baseband chips. Innox believes that for architecture, some value-added applications related to radio frequency will become the most likely part of RF transceiver chip integration. This architectural change will slowly transform the traditional RF transceiver part into a RF multi-service platform for multiple applications, into a transceiver + tuner integration, including GPS, digital broadcasting, etc.

 Impact on Others · Jammer: Negatively impacts others by blocking their communications (e.g., a jammer in a café stops all customers from making calls). · Booster: Positively impacts others by improving signal quality for everyone in the coverage area (e.g., a WiFi booster helps all residents in an apartment building). Example:If you’re in a remote cabin with no cell service, a booster would pick up the weak signal from a distant tower and let you make calls. If you’re in a prison and want to stop inmates from using cell phones, a jammer would block all signals in the facility. In short, the fundamental difference is their purpose: jammers block signals to prevent communication, while boosters amplify signals to improve it.

Unwanted signal interference (e.g., dropped calls, slow WiFi) occurs when an external signal disrupts the target signal. It can come from various sources (microwaves, Bluetooth devices, illegal jammers). Here’s how to handle it: Part 1: Detecting Interference 1. Observe Patterns: Note when interference occurs. For example, if your WiFi slows down when you use the microwave (2.4GHz), the microwave is the culprit. 2. Use Tools: · Spectrum Analyzer: Displays the frequency spectrum to identify abnormal signals (e.g., a strong 2.4GHz signal that’s not your WiFi). · Signal Detector: Locates wireless signals (e.g., rogue WiFi routers or jammers). · Mobile Apps: Apps like WiFi Analyzer (Android) scan for WiFi interference. 3. Test Devices: If only one device is affected, the problem is with the device (e.g., a faulty antenna). If multiple devices are affected, the interference is external. Part 2: Dealing with Interference 1. Adjust Frequency/Channel: · WiFi: Switch to a less crowded channel (e.g., from channel 6 to 11 in 2.4GHz). Many routers have an "auto-channel" feature. · Cell Phones: Try switching to a different network (e.g., 5G instead of 4G) if available. 2. Increase Distance: Move your device away from interference sources (microwaves, Bluetooth speakers). Keep your WiFi router away from the kitchen. 3. Use Shielding: Metal or conductive materials (e.g., aluminum foil) can block interference. Line your router’s enclosure with foil (though this may reduce your signal range). 4. Upgrade Equipment: · WiFi Routers: Switch to a dual-band (2.4GHz/5GHz) or mesh network. The 5GHz band is less crowded. · Antennas: Replace the default antenna with a high-gain antenna to improve reception. 5. Report Illegal Interference: If you suspect an illegal jammer (e.g., someone blocking cell signals in a public place), report it to your local regulatory body (e.g., FCC in the US). Part 3: Preventing Future Interference · Plan Your Network: Use a spectrum analyzer to scan for interference before setting up a WiFi router. · Use Quality Devices: High-quality routers and antennas are less prone to interference. · Update Firmware: Firmware updates often include anti-interference improvements.

Signal jammers and boosters serve opposite purposes in wireless communications. Here’s how they differ: 1. Primary Purpose · Jammer: Disrupt or block communications. It prevents target devices (e.g., cell phones) from receiving/transmitting signals. · Booster: Enhance or improve weak signals. It extends the range of a signal and improves quality for devices with poor reception. 2. Working Principle · Jammer: Uses blocking (overpowering the target signal) or spoofing (sending fake signals) to interfere. · Booster: Receives a weak signal, amplifies it, and retransmits it to target devices. 3. Applications · Jammer: Used in secure environments (prisons, exam halls) to prevent unauthorized communication. · Booster: Used in areas with poor coverage (rural areas, basements) to improve communication. 4. Legality · Jammer: Illegal in most countries without authorization. · Booster: Legal in most countries (provided they meet regulatory standards).

Using a signal jammer is illegal in most countries without explicit authorization. The primary reason is that jammers disrupt critical communications (e.g., emergency calls) and violate public network rights. Here’s an overview of global rules: · United States: The FCC strictly prohibits jammers. Violators face fines up to $16,000 and imprisonment. Exceptions are limited to federal agencies (e.g., FBI). · European Union: Jammers require CE certification but are restricted to secure environments (prisons, military bases). Private use is banned. · Canada: Industry Canada prohibits jammers except for government use. Unauthorized use leads to fines and criminal charges. · Australia: The ACMA bans jammers under the Radiocommunications Act. Exceptions are for law enforcement. Legal Use Cases:Jammers are permitted in scenarios where unauthorized communication must be prevented: · Prisons: Stop inmates from using cell phones to coordinate crimes. · Exam Halls: Prevent cheating via wireless devices. · Military Bases: Protect sensitive information from eavesdropping. Consequences of Illegal Use: · Fines: Hefty penalties (e.g., $16,000 in the US, €100,000 in the EU). · Imprisonment: Criminal charges for repeat offenders. · Confiscation: Seizure of the jammer and equipment. Tips for Compliance: · Check local laws before purchasing a jammer. · Obtain authorization from the relevant regulatory body (e.g., FCC). · Use approved devices that meet technical standards. In summary, while jammers have legitimate uses, their deployment is heavily regulated to protect public safety.

A signal booster (or repeater) is a device that enhances weak wireless signals by receiving, amplifying, and retransmitting them. It’s used in areas with poor coverage (e.g., rural areas, basements) to improve communication quality for cell phones, WiFi, or TV. The working principle is simple: 1. Receive: An external antenna picks up the weak signal from a source (e.g., a cell tower). 2. Amplify: A power amplifier boosts the signal strength. 3. Transmit: An internal antenna retransmits the amplified signal to target devices (e.g., smartphones). This process extends the signal range and reduces issues like dropped calls, slow internet, or pixelated TV. There are several types of boosters, each for specific technologies: · Cell Phone Boosters: Target 2G/3G/4G/5G signals. They include an external antenna (roof-mounted), an amplifier (indoor), and an internal antenna (for weak areas). Popular in rural areas. · WiFi Boosters (Range Extenders): Extend WiFi coverage. They receive the existing signal, amplify it, and retransmit it to areas with weak reception (e.g., upstairs bedrooms). · TV Signal Boosters: Improve over-the-air (OTA) TV signals. Mounted on the roof with the TV antenna, they reduce static or pixelation. While boosters are beneficial, over-amplification is illegal in many countries (e.g., the US). It can interfere with other networks, so always choose a booster that matches your target frequency (e.g., 4G for 4G signals). In short, boosters work by amplifying weak signals—making them a valuable tool for addressing poor wireless communication.