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Browse Prior Art Database

MEANS TO REDUCE CONNECTOR PINS AND SELECT RADIO RF PATH

IP.com Disclosure Number: IPCOM000006751D
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2002-Jan-29
Document File: 1 page(s) / 63K

Publishing Venue

Motorola

Related People

Robert B. Ford: AUTHOR [+2]

Abstract

The circuit eliminates a pin or an extra mechanical RF plunger in the radio accessory connector while still providing for the RF path selection between the radio antenna or external accessory antenna.

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INC. Technical Developments Volume18 March 1993

MEANS TO REDUCE CONNECTOR PINS AND SELECT RADIO RF PATH

by Robert B. Ford and Joseph Patino

  The circuit eliminates a pin or an extra mechanical RF plunger in the radio accessory connector while still providing for the RF path selection between the radio antenna or external accessory antenna.

  Past RF switching methods required a dedicated RF selection contact or mechanical switch actuator at the accessory connector area of the radio. Future radios will be required to support more features and be more mini- aturized. The accessory connector must be kept small and have as few pins as possible, so connector pins will need to serve multiple functions. The advantage pro- vided by this circuit is that it provides 3 separate func- tions using only the RF pin and ground. The 3 functions are 'external RF selection: 'actual RF path: and 'external RF PA pre-keying:

  Referring to the diagram below, an internal radio selection detector circuit monitors the DC voltage sta- tus of the external RF signal path. With no accessory connected or with an accessory that does not require external w, the DC voltage is at a high state due to Rl

(+5 V DC typical). When an accessory requiring exter- nal RF is attached to the,radio, the RF path which is now also the select path becomes low voltge due to R2
(1.2 V DC typical). This changes the output conditions of the detector causing the &dio RF switch to route RF to the external path....