Attenuator chip

    RF attenuator is one of the most important components in RF and microwave systems. It is a bidirectional dual port passive device. As the name suggests, an attenuator attenuates or reduces the power level of the signal passing through it, just like a resistor in an electronic circuit. In the complex test environment, the attenuator not only attenuates the signal, but also has other important characteristics, such as impedance matching, signal level control and isolation.

一、 Attenuator type

1. Fixed attenuator: it has fixed attenuation value in the whole bandwidth, such as 1dB, 3dB, 10dB and 40dB.

2. Step attenuator: This attenuator is between fixed attenuator and variable attenuator. It provides different attenuation values within a specific range, but these attenuation values can only be selected by the user according to fixed increments (such as 0.5dB and 1dB).

3. Continuously variable attenuators: these attenuators provide finer attenuation output and can output any value within a given range. They use more complex solid-state components and allow more complex control mechanisms to achieve more accurate signal attenuation.

4. Programmable attenuator: also known as program-controlled step attenuator, they can be controlled by software. The control interface includes USB, Ethernet, serial port, etc. it is usually used in automatic test environment, and its attenuation range is 0 ~ 110 dB.

二、 Composition of RF attenuator

1. Attenuation part: it is the main part of the attenuator and realizes the attenuation function of the attenuator. Usually it includes a line with resistance in series or parallel with ground. It may vary by structure, type, and application. The most common types are PI type attenuators and T-type attenuators. In addition, there are some complex types, such as bridging t-attenuator, reflective attenuator and balanced attenuator.

2. Heat sink: this part is used as the heat dissipation system of attenuator. The high-power attenuator will continue to generate heat during operation. If the generated heat is not emitted, the device will be damaged. In addition, surface mounted attenuators and low-power attenuators generally do not need large heat dissipation seats due to their small heat.

3. Connectors: in common attenuation, we use almost all standard types of connectors, such as SMA, SMB, BNC, n-type, DIN type, etc.

4. Frequency range: refers to that the performance of the attenuator meets the requirements of the index within a given frequency range.

5. Attenuation: the attenuator describes the reduction degree of power after the power passes through the attenuator. Its size is determined by the material and structure constituting the attenuator, the unit is dB, and the range can be from 0dB to 100dB or more.

6. Attenuation accuracy: refers to the maximum value of attenuation deviation from the nominal value within the frequency range of the attenuator, in dB.

7. In band fluctuation: the value is within the frequency range of the attenuator, and the difference between the maximum and minimum attenuation value of the attenuator is in dB.

8. Power capacity: refers to the power that the attenuator can withstand. In DBM or W, the attenuator shall be able to safely handle the required power. In practical use, it is recommended to select an attenuator with a power capacity higher than the required power. Special attention should be paid to the heat dissipation of the attenuator in the high temperature environment. It is best to use the attenuator with better heat dissipation performance.

9. Impedance matching: to accurately attenuate the signal power, the RF power attenuator must match the impedance, otherwise it will form a standing wave or reflection, which will affect the measurement accuracy. For the input of the attenuator, the input impedance should match the output impedance of the signal source; For the output of the attenuator, the output impedance should match the load impedance. Because the RF power attenuator generally does not need impedance conversion, the input impedance, output impedance, load impedance and signal source output impedance are equal.

三、 Use of attenuator

1. Provide attenuation and protect the instrument from reflected waves.

2. Impedance matching to provide better isolation in complex transmitter and receiver networks.

3. Power control uses step attenuators and programmable attenuators in specific applications.