Temperature compensated RF circuitry

Abstract

A temperature compensated RF sensing circuitry for use in a remotely mountable weatherproof bi-directional, half-duplex switching amplifier system designed to provide maximum range for low power half-duplex radios such as Spread Spectrum radio transceivers in utilizing a voltage reference that is connected between a power supply circuit and a reference potential with a thermistor for temperature compensation purposes.

28 . Temperature compensated RF sensing circuitry, comprising: 
 a first voltage reference connected between a power supply voltage and a reference potential,    a thermistor being connected to said first voltage reference to provide temperature compensation therefor,    the output of said first voltage reference connected to one end of a pair of series connected diodes, said output of said first voltage reference forward biasing said pair of series connected diodes in the forward direction to just below the point of conduction,    the common connection between said pair of serially connected diodes being coupled to an external source of radio frequency (RF) signal,    the other end of said pair of serially connected diodes being connected to a comparator circuit, wherein:    when the amplitude of the source of radio frequency signal is zero or below a predetermined threshold, this generates one state output of the comparator circuit, and when the amplitude of the source of radio frequency signal is at or above said predetermined threshold, this generates a second state output of the comparator circuit.    
   
   
       29 . A temperature compensated RF detection circuit as in  claim 28 , wherein: 
 said source of radio frequency signal is a transceiver, remote from said temperature compensated RF detection circuit, and    said comparator circuit output states control a bidirectional switching radio frequency amplifier to control said amplifier into either a receive or a transmit condition.    
   
   
       30 . A temperature compensated RF detection circuit as in  claim 29 , wherein: 
 a second voltage reference with an output is connected between a power supply voltage and a reference potential,    said comparator circuit comprises a pair of differential comparators, each with two inputs and an output respectively,    one input of each of said pair of differential comparators is connected to said output of said second voltage reference,    the other input of one of said pair of differential comparators is connected to said other end of said pair of serially connected diodes, and    the other input of the other of said pair of differential comparators is connected to the output of said one of said pair of differential comparators,    whereby only one of said pair of differential comparators has a High output at any time, thereby indicating said amplitude of said source of radio frequency signal.    
   
   
       31 . A temperature compensated RF detection circuit as in  claim 30 , wherein: 
 said first and second voltage references comprise a plurality of serially resistors between said power supply voltage and said reference potential.