After many years of discussion, development and promise, 5G network deployments began in 2019 in China, South Korea and other countries. According to the 3GPP (3rd Generation Partnership Project) mobile telecom standards specifications, the 5G NR (new radio) spec defines three classes for base stations – wide area base station, medium area base station and local area base station. These are also known as Macro BTS, Micro BTS and Pico BTS, respectively.
We’ve heard a lot of hype about what 5G will bring to mobile users but the key technology advancements 5G definitely does deliver are Massive MIMO which provides better throughput and better spectrum efficiency, as well as beamforming which boosts cell range and capacity for stronger, clearer signals.
In terms of channels, Macro BTS systems have from four up to 32 and 64 channels for sub-6 GHz and up to 512 or 1024 channels for mmWave. In this particular discussion, we call the Macro BTS with fewer than 16 channels a legacy Marco BTS and those with 16 or more channels, mMIMO BTS. This discussion mainly focuses on legacy Macro BTS.
Legacy Macro BTS systems aim to provide wide coverage at low costs. These normally have four channels for FDD mode and eight channels for TDD mode. The output power varies from 80 to 320W. Due to the lower number of channels, the output power of each channel reaches 40W or even 80W, which requires RF chips with high integration, lower power consumption and high reliability, as well as decent noise figure.
As a leading RF solutions vendor, Renesas (which acquired IDT in 2019) has a complete RF signal chain solution for customers from the LNA, pre-driver and TX VGA to high-performance switches used for digital predistortion (DPD) path, as shown in Figure 1.
For example, the F01xx dual-channel LNA family includes F0109, F0110 and F0111 which covers a wide frequency range from 600 MHz to 2.7 GHz. F01xx LNAs offers low NF and deliver excellent return loss in balanced mode with typical output return loss of -20dB and better than -15dB.
Following the F01xx, F0442/43 dual path broad band DVGAs support wide frequencies from 600 MHz to 2700 MHz.F0442/43 offer a wide gain control range and flexible gain step, supporting SPI and I2C interface. An external hard pin can be configured to fast gain switching.
The F448x family of quad-channel, high-performance TX VGAs includes F4481, F4482 and F4483 and covers the frequency range from 400 MHz to 4 GHz. F448x integrates balun, filter and DSA, which eliminates the external balun and filter used in a traditional Tx line up. The four channels can be configured by SPI efficiently and independently. Coupled with an F1471 high-power (0.5W) wide band pre-driver, F448x Tx VGAs offer a high-performance Tx lineup.
For the DPD path, the recently released F2934 high reliability SP2T RF switch features both a smaller package size (3x3 mm) and better isolation and high linearity performance than the most popular existing switch on the market.
Beyond the amplifier and VGA, Renesas can provide the necessary high-performance switches, including F2932 (SP2T), F2914 (SP4T) and F2915 (SP5T). Additionally, Renesas is developing an advanced bias controller for use in PAs and high integration modules integrating Doherty PA, driver, VGA and bias controller, which further benefit customers by shortening the development cycle and lowering overall cost. We are committed to advancing technology development for continued system improvement as seen in our focus from 3G to 4G LTE and now with next generation Macro BTS solutions for 5G.