Since its promotion in 2018, the 5th generation (5G) cellular radio frequency (RF) communication protocol has promised to achieve an order of magnitude improvement in the way individual users, industrial machines, and cloud computing servers send and receive data. In order to meet the requirements of International Mobile Telecommunication-2020 (IMT-2020), the Third Generation Partnership Project (3GPP) has developed the 5G standard, which specifies a data transmission rate of 10 Gbps, which is 10 to 100 times faster than previous 4G standards. Compared to the 4G LTE protocol, this standard also requires a 1000 fold increase in bandwidth per unit area to allow for a maximum increase of 100 times in the number of devices connected within the area. At the same time, the organization insists on achieving 99.999% network availability while reducing energy consumption of base stations and connected devices.
By mid-2025, there will be over 2.25 billion 5G connections worldwide, with over 182 million in North America. Now, network architects have turned their attention to standalone (SA) devices, which only support 5G frequencies and protocols, can achieve faster upload and download speeds, and support advanced industrial Internet of Things (IIoT) and machine to machine (M2M) communication, with network latency as low as 1 ms.
The development of new devices for the construction of 5G infrastructure has stimulated the demand for various electronic components, including ubiquitous capacitors. In 5G applications, capacitors are versatile devices that can filter out unwanted frequencies and eliminate radio frequency interference, pair with inductors to regulate antennas, decouple power rails to stabilize voltage levels, and balance antenna connections. When designing 5G devices and cellular base stations, engineers must choose suitable capacitors to meet the specific performance, size, and cost requirements of each application.
Capacitors for 5G antenna applications
The antennas of 5G infrastructure support three frequency bands in higher RF regions: the low frequency band below 2 GHz, the mid frequency band between 2 GHz and 6 GHz, and the high frequency band between 24 GHz and 100 GHz. By pairing multi-layer ceramic capacitors (MLCC) with inductors to form an antenna oscillator, it is possible to tune to specific radio frequencies. The capacitors of 5G infrastructure must be able to handle higher frequencies of the protocol (Figure 1).
Application of MLCC in RF Communication Field
Figure 1: MLCC is widely used in the field of RF communication. Engineers must carefully select capacitors to manage the higher RF currents in 5G infrastructure. (Image source: KEMET Corporate)
KEMET's HiQ CBR series capacitors (Figure 2) are one of them. The capacitance of this series of capacitors ranges from 0.1 pF to 100 pF, and can operate for a long time in the frequency range of 1 MHz to 50 GHz without overheating or losing capacitance characteristics. Due to the use of Class I dielectric, HiQ CBR capacitors can operate within a temperature range of -55 ° C to+125 ° C with a capacitance change of less than ± 30 ppm/° C. Within a DC voltage range of 6.3 V to 500 V, this capacitor can also maintain very stable performance without aging.
KEMET HiQ CBR capacitor
Figure 2: HiQ CBR capacitors are MLCCs designed for higher frequencies used in 5G infrastructure. This surface mount device (SMD) uses Class I ceramic dielectric, paired with base metal conductors, and features matte tin coated end caps. (Image source: KEMET Corporation)
HiQ CBR capacitors are composed of multiple layers of base metal electrodes (Figure 3). The electrode material is copper, and each electrode layer is separated and embedded with ceramic material. The ceramic material here is Class I C0G dielectric CaZrO3. The metal end cap is used as the electrical connection part for the electrode, making it easy to solder the surface mount device (SMD) onto the printed circuit board (PCB).
Internal electrode MLCC layer embedded with ceramic dielectric
Figure 3: The internal electrode layer of MLCC (such as HiQ CBR series products) is embedded in ceramic dielectric, with metal connections at the end caps. (Image source: KEMET Corporation)
Thanks to its material and structure, HiQ CBR capacitors have low loss performance, represented by the quality factor Q, which is the reciprocal of the dissipation factor (DF). When testing HiQ CBR capacitors with a capacitance value of 30 pF or higher under conditions of 1 MHz ± 100 kHz and 1.0 ± 0.2 VRMS, their Q value is greater than or equal to 1000. For capacitors with lower capacitance values in this product series, Q = 400 + 20C， Where C is the capacitance value.
When designing electronic products for high-frequency RF applications, engineers are also looking for capacitors with low equivalent series resistance (ESR) and low equivalent series inductance (ESL), which can help achieve high self resonant frequency (SRF). SRF is the frequency at which a capacitor resonates, causing it to lose capacitance and act as an inductor, therefore SRF must be much higher than the operating frequency. The SRF range of HiQ CBR capacitors is from 600 MHz (100 pF capacitors) to 12000 MHz (0.1 pF capacitors).
The end caps of HiQ CBR capacitors are treated with matte tin and can be soldered onto standard printed circuit boards. This type of capacitor has common housing sizes, including 0201 (0.2 "x 0.1"), 0402 (0.4 "x 0.2"), 0603 (0.6 "x 0.3"), and 0805 (0.8 "x 0.5"). These devices have passed lead-free certification and comply with RoHS regulations.
With its unique performance characteristics and external dimensions, the HiQ CBR series capacitors play a good role in 5G cellular base stations, communication networks, RF power amplifiers (PA), wireless local area networks (LAN), global positioning system (GPS) networks, and Bluetooth communication. This series of capacitors can also be used for signal processing such as DC blocking, filtering, impedance matching, coupling, and bypass.
To reduce interference and signal noise, designers can add similar KEMET FLEX SUPPRESSOR ® This sheet or roll shaped polymer metal composite material (Figure 4) contains micrometer sized magnetic particles dispersed in a flexible polymer substrate to suppress electromagnetic waves or resonances, improve magnetic flux convergence, or reduce noise generated by electronic devices in the 5G frequency range of 3 GHz to 40 GHz.