Key facts
- Brand
- Linear Technology
- Model
- LT5528
- Industry
- Industrial
- Documents
- 3
- Languages
- EN
- Last added
- 2012-06-05
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LT5528 WCDMA ACPR AltCPR Measurements Design Note 375
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.
Linear Technology LT5528 specifications
| Measurement Bandwidth (Carrier) | 5MHz |
|---|---|
| ACPR Measurement Offset | 3.84MHz centered at 5MHz away from carrier center |
| AltCPR Measurement Offset | 10MHz away from carrier center |
| Resolution Bandwidth for Noise Measurement | 30kHz |
| Video Bandwidth for Noise Measurement | 100kHz |
Source: Linear Technology LT5528 WCDMA ACPR AltCPR and Noise Measurements Application Note 99
All Linear Technology LT5528 documents by type
How to use the product for one specific task, with worked examples.
Questions answered in these manuals
What is the purpose of ACPR and AItCPR measurements?
They are important measures of spectral regrowth for digital communication systems that use WCDMA modulation.
Why is measuring the LT5528 difficult?
Because its dynamic range may rival that of the measurement equipment, making it hard to account for system noise.
Why is a free running RF generator recommended for this test setup?
It provides superior noise performance; a noisy LO signal may corrupt the modulator output and degrade ACPR measurement accuracy.
From: Linear Technology LT5528 WCDMA ACPR AltCPR and Noise Measurements Application Note 99
What is the LT5528?
The LT5528 is a high linearity direct I/Q modulator that accepts WCDMA modulation at baseband inputs and generates a WCDMA modulated signal at the RF output.
From: Linear Technology LT5528 WCDMA ACPR AltCPR and Noise Measurements Application Note 99
What is the purpose of this Application Note?
This document describes a method to accurately measure internal and external phase and timing errors for a high performance direct I/Q modulator.
From: Linear Technology AN102 Measuring Phase Delay Errors in I/Q Modulators Application Note
What specific requirement is needed for -60dBc image suppression?
To achieve -60dBc image suppression, the residual I/Q phase error must be below 0.16°.
From: Linear Technology AN102 Measuring Phase Delay Errors in I/Q Modulators Application Note