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# Calculation Method to Predict CDMA ACPR from Two-Tone Performance Based on an Envelope Power Probability Distribution Function (PDF)

IP.com Disclosure Number: IPCOM000007827D
Original Publication Date: 2002-Apr-25
Included in the Prior Art Database: 2002-Apr-25
Document File: 4 page(s) / 69K

Motorola

## Related People

Yinglei Yu: AUTHOR

## Abstract

Based on envelope power probability distribution function (PDF), a calculation method to predict CDMA ACPR from two-tone performance is proposed. This method can be applied to ACPR testing or CAD simulation. A computation algorithm is also proposed and it can be easily implemented into CAD simulation or auto-testing system.

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Calculation Method to Predict CDMA ACPR from Two-Tone Performance Based on an Envelope Power Probability Distribution Function (PDF)

# Yinglei Yu

Motorola, Inc.

## Abstract

Based on envelope power probability distribution function (PDF), a calculation method to predict CDMA ACPR from two-tone performance is proposed. This method can be applied to ACPR testing or CAD simulation. A computation algorithm is also proposed and it can be easily implemented into CAD simulation or auto-testing system.

The non-linearity of a RF system is traditionally characterized by two-tone testing and the 3rd order inter-modulation distortion (IMD3) or the 3rd intercept point (IP3) is used as the figure of merit. However, the non-linearity of the CDMA systems are specified by adjacent channel power (ACP) or adjacent channel power rejection ratio (ACPR).  Therefore, it is necessary to associate ACPR with 2-tone IMD performance.

The two-tone performance can be calculated by the following equations:

(1)

These calculations should be interpreted based on the envelope power probability distribution function (PDF). By looking at the power PDF function of the sinusoidal envelope, it is reasonable to interpret PIM3 and a3 as the measurement of the 3rd in-band distortion of the system with the input average power equal to the average power of the 2-tone signal and input envelope power PDF equal to psin(x). In another words, if the system is excited with a signal with the same envelope power PDF as psin(x), it is assumed that the 3rd in-band distortion can be characterized by using a3, which can be calculated by equation (1) from the PIM3 of 2-tone input with the same average output power Pout. Moreover, if the CDMA input signal can be represented by several signals Pi with uniform spectrum density and different power level...