THE THIRD GENERATION PARTNERSHIP PROJECT (3GPP) Long Term Evolution (LTE) initiative promises to enhance third-generation (3G) networks, thereby enabling new service opportunities in mobile TV and video. Yet challenges exist in achieving these capabilities in consumer devices. For example, the power amplifier (PA) contributes significantly to handset power consumption. As an active device, it also exhibits nonlinear behavior that can be problematic. In a four-page application note, Agilent Technologies shows how accurately testing the PA during design and optimization can ensure that the PA is both highly efficient and linear.
The document, titled "Ensuring Quick, Accurate ACPR Measurements of LTE Power Amplifiers," notes that LTE PA testing is made difficult by several factors: the LTE system's complexity, the nature of its signal (e.g., wideband, modulated, and relatively noise-like), and the technology's continuing evolution. Adjacent-channel power ratio (ACPR), a measure of a system's linearity, is necessary for evaluating PAs in LTE systems. Although this measurement is usually conducted with spectrum analyzers and software, these tools do not allow a PA's ACPR to be measured quickly and accurately. In addition, they fail to allow the test setup or actual test to be simplified. The application note suggests using a flexible, general-purpose signal generator and signal analyzerboth of which must be capable of dealing with the changing requirements and complexity of the LTE standard. The document details the required features and capabilities of these instruments before discussing some examples from the company.
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