This document introduces the importance of LT5528 WCDMA ACPR and AltCPR measurements, as well as the test setup for these measurements. The LT5528 is a high linearity direct I/Q modulator that accepts complex modulation signals and generates modulated RF signals at the RF output. However, accurately measuring the spectral regrowth of the LT5528 is challenging due to its dynamic range potentially rivaling that of the measurement equipment, necessitating the consideration of measurement system noise. The document provides specific test setups and measurement parameters.
This document provides a design note on measuring Adjacent Channel Power Ratio (ACPR) and Alternate Channel Power Ratio (AItCPR) for the LT5528, a high linearity direct I/Q modulator used in WCDMA systems. It explains that accurate measurement is difficult due to the device's dynamic range rivaling standard equipment.
The text details a specific test setup involving an Agilent signal generator and spectrum analyzer, emphasizing the need for low noise floors and wide dynamic ranges. It outlines steps to measure system noise, configure resolution bandwidths, and calculate true spectral regrowth by subtracting the analyzer's noise floor from measured DUT power.
They are important measures of spectral regrowth for digital communication systems that use WCDMA modulation.
Because its dynamic range may rival that of the measurement equipment, making it hard to account for system noise.
A 30kHz resolution bandwidth is used because the spectrum analyzer shown has the lowest noise figure at that setting.