Browse Prior Art Database

RSSI CONDITIONING CIRCUIT

IP.com Disclosure Number: IPCOM000006453D
Original Publication Date: 1992-May-01
Included in the Prior Art Database: 2002-Jan-04
Document File: 1 page(s) / 57K

Publishing Venue

Motorola

Related People

Richard LaLau: AUTHOR

Abstract

In an effort to reduce post assembly hand tuning, electical means must be sought to adjust many radio parameters. One of these parameters, the Receive Sig- nal Strength Indicator (RSSI), must be adjusted so that its slope and offset are consistent from radio to radio. This invention describes a very simple method of vary- ing both RSSI slope and offset without constant microcontroller monitoring while the transceiver is in receive mode.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 64% of the total text.

Page 1 of 1

MOTOROLA INC. Technical Developments Volume 15 May 1992

RSSI CONDITIONING CIRCUIT

by Richard LaLau

PROBLEM

  In an effort to reduce post assembly hand tuning, electical means must be sought to adjust many radio parameters. One of these parameters, the Receive Sig- nal Strength Indicator (RSSI), must be adjusted so that its slope and offset are consistent from radio to radio. This invention describes a very simple method of vary- ing both RSSI slope and offset without constant microcontroller monitoring while the transceiver is in receive mode.

SOLUTION

   This invention electrically manipulates the RSSI slope and offset by varying the gain and input bias level to a two stage op-amp buffer circuit as shown in Figure 1.

  The microcontroller writes configuration data to the D/A converter which sets the gain and offset require- ment to the hvo bulks. This method eliminates the need for continuous RSSI monitoring by the microcontroller allowing it to shut down during receive mode saving battery current. Gain is adjusted first so that DC offset is not amplified.

   The circuit requires two op-amps, a few resistors and a FET transistor biased in the triode region to act as voltage variable resistance (Reff in Figure 1). The non- inverting op-amp summing circuit is rarely used because of the interaction between input terminals and its corresponding al&t on gain. This interaction does not pose a problem since this circuit manipulates DC sig- nals only, The second rarely used circu...