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METHOD TO CONSERVE POWER IN SUBSCRIBERS USING C/I+N DETECTION ALGORITHM

IP.com Disclosure Number: IPCOM000007109D
Original Publication Date: 1994-Feb-01
Included in the Prior Art Database: 2002-Feb-26
Document File: 3 page(s) / 245K

Publishing Venue

Motorola

Related People

Bradley Jentz: AUTHOR

Abstract

The expanding market for wireless communica- tion systems has resulted in a customer demand for portable radio products that also meet the practical requirements of reduced cost, size, and power con- sumption. One area of technology that is being looked into as part ofthe solution to this problem is to design and implement a direct conversion receiver IC that can be used in both low tier and high tier product lines. The most stringent technical specifi- cations for this IC are going to be set by the high tier, spectrum efficient linear systems. Mixers and amplifiers with third-order intercept points on the order of + 10 dBm will be needed to prevent unwanted IM interference.

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(&#OTOFtOLA Technical Developments Volume 21 February 1994

METHOD TO CONSERVE POWER IN SUBSCRIBERS USING C/I+N DETECTION ALGORIThM

by Bradley Jentz

direct conversion receiver IC, but have no need for the dynamic IP3 algorithm.

1 INTRODUCTION

2 DESCRIPTION

  The expanding market for wireless communica- tion systems has resulted in a customer demand for portable radio products that also meet the practical requirements of reduced cost, size, and power con- sumption. One area of technology that is being looked into as part ofthe solution to this problem is to design and implement a direct conversion receiver IC that can be used in both low tier and high tier product lines. The most stringent technical specifi- cations for this IC are going to be set by the high tier, spectrum efficient linear systems. Mixers and amplifiers with third-order intercept points on the order of + 10 dBm will be needed to prevent unwanted IM interference.

  Such high linearity requirements will be met at the expense of additional current drain which will not be necessary in the low tier product lines. What has traditionally been done in the past is to design dual-mode mixers/amplifiers that can be pro- grammed to run in either a high performance, high current drain mode, or in a low performance, low current drain mode of operation. In order to fiuther reduce power consumption in the high tier prod-

ucts, there exists a need for a dynamic IP3 algo- rithm that will enable the receiver to detect when on channel interference is low enough that it can switch to the low current drain mode of operation without penalizing system performance, and return to the high current drain mode only when on chan- nel noise due to IM interference is high enough that it begins to degrade system performance.

  The invention described in this paper is a method for generating such a dynamic IP3 algorithm. It not only helps to reduce power consumption, but it also does not require that any additional circuits be added onto the direct conversion receiver IC itself. There- fore, a cost penalty is not incurred in the form of additional chip area. This is especially important for the low tier product lines which will be using the

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  The dynamic IP3 algorithm is based on the stand- ard control circuit model which includes a detector, a circuit to be controlled, and an algorithm which uses the output of the detector to generate a control signal. The approach that was taken to design such an algorithm was to take known elements, and com- bine them in a new way to produce the desired results.

  In order to determine whether or not the receiver can be operating in the low current drain mode, there needs to be some kind of detector which gives an ongoing measure of both the average carrier and interferer signal power that is present on the received channel. An example of this kind of detector is the SQE algorithm that was designed for the Motorola MIRS radio system. This algorithm calculates the avera...