MIPI RFFE is the specification of a bus interface specifically tailored for the needs of current and future mobile wireless systems to control the slave devices in an RF front-end. This article gives an overview of MIPI RFFE Version 1.0 and discusses the desires and rationale behind the development of RFFE, including a survey of existing alternatives.
Mobile phone RF systems have become increasingly complex and will benefit from a single control interface solution.
Need for Unification in Mobile Radio Platforms
During the last decade, the number of mobile phones has grown rapidly, with 1.4 billion devices shipped in 2010, and with no saturation of demand in sight. Over that same time, the complexity has evolved from voice-only 2G devices, then to 3G and, most recently, 4G multi-functional smartphones. In addition, cellular communication complexity has increased with connectivity for Wi-Fi, Bluetooth, GPS, FM radio, and other capabilities.
The addition of these wireless standards creates a need for multi-radio solutions which cover ten or more frequency bands. As a result, the number of devices required for RF front-ends has also increased. For phone manufacturers, the complexities of control for all these devices becomes an ever-mounting challenge.
The MIPI Alliance Specification for RF Front-End Control Interface (RFFE) seeks to address this challenge by providing a bus interface connecting the transceiver, or radio, to the myriad of RF front-end devices such as LNAs, PAs, antenna switches, antenna tuners, DC/DC converters, filters, sensors, and the like. These devices may be controlled by an RFIC, or, alternately, some other source. This commentary provides a brief overview of the features of the RFFE spec which makes It uniquely suitable for the tasks presented by this burgeoning environment.