Murata has developed the industry's first negative mutual inductance to eliminate ESL parasitic inductance in capacitors to reduce noise

～Using fewer capacitors can reduce noise and help simplify design～

Murata Manufacturing Co., Ltd. (hereinafter referred to as "Murata") has developed the industry's first parasitic inductance noise reduction component "LXLC21 Series" (hereinafter referred to as "this product") that can suppress power supply noise in the harmonic range of several MHz to 1 GHz (3) by utilizing negative mutual inductance (1). Simply connecting one of these products to a capacitor in a power supply circuit eliminates the ESL (4) of the capacitor connected to this product and improves the noise cancellation performance of the capacitor. This makes it possible to suppress noise with fewer capacitors than before, contributing to the miniaturization and high-performance of electronic devices. Mass production of the LXLC21 series has already begun, and samples are now available.

In recent years, as electronic devices have become smaller and more functional, the density of circuit boards has increased and the number of ICs used has also increased. However, the switching power supply (5) noise generated by the IC is transmitted through cables and circuit board wiring, or emitted into the air as unnecessary electromagnetic waves, which may cause malfunctions or functional degradation of surrounding electronic devices. In order to achieve a safe, secure, and comfortable environment for the use of electronic devices, it is necessary to take noise countermeasures for the switching power supply.

A common power supply noise countermeasure is to configure a capacitor between the power line and GND, the propagation path of the power supply noise, to release the noise to GND. The noise elimination performance of this countermeasure method improves as the impedance of the capacitor used decreases. However, in the harmonic region, there is a parasitic component (called ESL) inside the capacitor that works as an inductor, which causes the impedance to increase, so it will reduce the noise elimination performance. Therefore, in devices that require high reliability, in order to improve the noise elimination effect in the harmonic region, the impedance is reduced by connecting multiple capacitors in parallel. However, this requires providing space for connecting multiple capacitors in parallel, which hinders the further miniaturization of electronic devices.

To this end, Murata has developed a power supply noise suppression component that uses the industry's first negative mutual inductance product, using its unique component design technology and ceramic multilayer technology to cancel out the parasitic inductance inside the capacitor and the parasitic inductance generated in the circuit board. By connecting one of these products, noise can be reduced with fewer capacitors, helping to save overall space.

Murata will continue to work on developing power supply noise suppression components that meet market needs and contribute to the miniaturization and advanced functionality of electronic devices.

Main Features

1. Noise suppression products for power circuits using the industry's first negative mutual inductance product

Transformer technology is used to generate negative mutual inductance, which cancels out the parasitic inductance components in the noise suppression capacitor and the wiring between the power line and GND. This makes it possible to suppress power supply noise in the harmonic region of several MHz to 1GHz.

2. Contribute to space saving

This contributes to space saving and improved reliability by reducing the number of components.

3. Achieve stable power supply noise cancellation performance

Since it is a non-magnetic material, it has no DC superposition characteristics (6) and can stably eliminate noise in response to current changes.

Main Specifications

Main Application

• Power supply circuits for the following applications

• Base stations, FA system-related and other industrial equipment

• Infotainment and other in-vehicle equipment

• Digital home appliances, PCs and other consumer devices

• Medical Devices

  
  

Notes

(1) Results of our investigation. As of May 13, 2024.

(2) Mutual inductance: refers to the change in induced electromotive force generated on one side of two adjacent magnetically coupled inductors due to a change in current on the other side. When two magnetically coupled inductors are connected in series, an inductance equivalent to that of the connected part is generated, which is called mutual inductance.

(3) Harmonics: Signals (usually noise) whose frequencies are integer multiples of the fundamental frequency (the same frequency as the signal itself).

(4) ESL (Equivalent Series L): Equivalent series inductance. As ESL increases, the impedance in the harmonic region also increases.

(5) Switching power supply: refers to a circuit that uses semiconductors to convert voltage by intermittently switching current.

(6) DC superposition characteristics: When DC current is applied, the inductance value usually decreases due to the magnetic saturation of the magnetic core. This characteristic is called DC superposition characteristics.

(7) AEC-Q200: Industry standard for passive components (capacitors, inductors, etc.) defined by the Automobile Electronics Council.