Temperature compensated power control circuit

Abstract

A temperature compensation technique employing a directional coupler providing signals from a forward sample port to a detector circuit for providing a DC output representative of transmitted power. A temperature compensation circuit including a current source is coupled to a reverse sample port of the directional coupler for providing a compensating DC bias current via said coupler, to the detector circuit. The detector circuit and the temperature compensation circuit each include matched diodes and corresponding circuits for tracking temperature and offsetting the effects of temperature on the DC output of the detector circuit.

1. A temperature compensated detector, comprising:
 a first conductor carrying signals to be detected;    a second conductor carrying signals electromagnetically induced therein from said first conductor;    a detector including a rectifier for providing an output signal representative of the signal carried by said first conductor; and    a temperature compensation circuit providing a compensating bias signal to said detector, said compensating circuit being connected in a manner to provide compensating bias signals to said detector so as to prevent loading thereof.    
     
     
       2. The temperature compensated detector of  claim 1 , wherein said first conductor and said second conductor comprise a directional coupler. 
     
     
       3. The temperature compensated detector of  claim 2 , wherein said detector is coupled to a terminal of said directional coupler for sensing a forward signal carried by said first conductor, and said temperature compensation circuit is connected to a different terminal of said directional coupler. 
     
     
       4. The temperature compensated detector of  claim 3 , wherein said different terminal comprises a reverse sample port that is AC terminated to a reference impedance. 
     
     
       5. The temperature compensated detector of  claim 1 , wherein said detector and said temperature compensation circuit each include a rectifier diode, and including corresponding circuitry for providing substantially an equal magnitude bias current to flow through each said diode. 
     
     
       6. The temperature compensated detector of  claim 1 , wherein said rectifier comprises a semiconductor diode. 
     
     
       7. The temperature compensated detector of  claim 1 , wherein said temperature compensation circuit includes a current source for sourcing substantially a constant current between said temperature compensation circuit and said detector, a magnitude of said current being substantially independent of temperature. 
     
     
       8. The temperature compensated detector of  claim 7 , further including a matched pair of semiconductor diodes, a first diode located in said detector and a second diode located in said temperature compensation circuit, and said current source sources current between said diodes. 
     
     
       9. The temperature compensated detector of  claim 8 , wherein said current source is configured to provide a constant current that is independent of temperature. 
     
     
       10. A temperature compensated detector, comprising:
 a directional coupler having an input port, an output port, a forward sample port and a reverse sample port;    a detector circuit including a rectifier, said detector circuit coupled to said forward sample port; and    a temperature compensation circuit coupled to said reverse sample port, said temperature compensation circuit providing a compensating bias to said detector circuit via said reverse sample port.    
     
     
       11. The temperature compensated detector of  claim 10 , wherein said detector circuit and said temperature compensation circuit each include a semiconductor diode of a matched diode pair, and each said diode carries substantially the same magnitude of DC bias current, and the magnitude of said bias current is independent of temperature. 
     
     
       12. The temperature compensated detector of  claim 10 , further including in combination a wireless transceiver, and wherein said temperature compensated detector is coupled between an amplifier and a load for controlling a power transmitted by said amplifier to said load. 
     
     
       13. A method of providing temperature compensation to a detector, comprising the steps of:
 coupling RF power to a directional coupler and therefrom to a load;    rectifying a signal provided at a forward sample port of said directional coupler to provide a DC voltage representative of the RF power; and    generating a DC bias signal that is independent of a rectifier temperature and coupling said DC bias signal to said forward sample port of the directional coupler, via a reverse sample port.    
     
     
       14. The method of  claim 13 , further including providing a matched pair of rectifier diodes, one rectifier diode coupled to said reverse port and another rectifier diode coupled to said reverse sample port. 
     
     
       15. The method of  claim 13 , further including terminating AC signals at said reverse sample port to a common circuit node. 
     
     
       16. A temperature compensated detector, comprising:
 a four-port directional coupler having an input port, an output port, a forward sample port and a reverse sample port;    a detector circuit coupled to said forward sample port, said detector circuit including a first semiconductor diode, a filter and an output providing a voltage corresponding to a signal carried between the input port and the output port of said directional coupler; and    a temperature compensation circuit coupled to said reverse sample port, said temperature compensation circuit including a current source and a second semiconductor diode, said current source being configured to source substantially the same amount of current between said first and second semiconductor diodes as the temperature changes.    
     
     
       17. The temperature compensated detector of  claim 16 , wherein said first and second semiconductor diodes have matched electrical characteristics. 
     
     
       18. A temperature compensated detector for an input signal, comprising:
   a directional coupler having an input port for receiving said input signal, an output port, a forward sample port and a reverse sample port;        a detector circuit, which includes a first rectifier, for producing an output signal representing the amplitude of said input signal, said detector circuit connected to said input port of said coupler;        a temperature compensation circuit which includes a current source that provides a DC bias current to a node from which said bias current is divided into first and second currents which flow through respective first and second circuit paths, said second path including a second rectifier;        said first path extending from said node through said reverse sample port of said coupler, said forward sample port of said coupler and through said first rectifier of said detector circuit; and        said first path and said second path having substantially equal resistance wherein said first and second currents are substantially equal.     
     
     
       19. The temperature compensated detector of  claim 18  wherein said current source is a temperature compensated constant current source. 
     
     
       20. The temperature compensated detector of  claim 18  wherein said first path includes a first resistor connected in series with said first rectifier between said node and a common terminal and said second path includes a second resistor in series with said second rectifier between said node and said common terminal. 
     
     
       21. The temperature compensated detector of  claim 20  wherein said detector circuit includes a first capacitor connected in parallel with said first resistor and said temperature compensation circuit includes a second capacitor connected in parallel with said second rectifier. 
     
     
       22. The temperature compensated detector of  claim 18  wherein said first and second rectifiers are matched diodes. 
     
     
       23. The temperature compensated detector of  claim 18  wherein said detector circuit is an RF detector circuit. 
     
     
       24. The temperature compensated detector of  claim 18 , further including in combination a wireless transceiver and wherein said temperature compensated detector is coupled between an amplifier, said amplifier providing said input signal, and a load for controlling a power transmitted by said amplifier to said load. 
     
     
       25. A temperature compensated detector for an input signal, comprising:
   a directional coupler having an input port for receiving said input signal, an output port, a forward sample port and a reverse sample port;        a detector circuit, which includes a first rectifier connected in series with a first resistor between said forward sample port of said coupler and a common terminal and a first capacitor connected in parallel with said first resistor, for producing an output signal at a junction node between said first rectifier and said first capacitor, said output signal representing the amplitude of said input signal;        a temperature compensation circuit which includes a constant current source that provides a DC bias current to a first node from which said bias current is divided into first and second currents which flow through respective first and second circuit paths, said second path having a second rectifier connected in series with a second resistor between said first node and said common terminal;        said first path extending from said first node through said reverse sample port of said coupler, said forward sample port of said coupler, said first rectifier and said first resistor of said detector circuit to said common terminal; and        said first path and said second path having substantially equal resistance wherein said first and second currents are substantially equal.     
     
     
       26. The temperature compensated detector of  claim 25  wherein said constant current source is temperature compensated. 
     
     
       27. The temperature compensated detector of  claim 25  wherein said first rectifier is matched to said second rectifier and said first and second resistors have substantially the same resistance. 
     
     
       28. The temperature compensated detector of  claim 25 , further including in combination a wireless transceiver and wherein said temperature compensated detector is coupled between an amplifier, said amplifier providing said input signal, and a load for controlling a power transmitted by said amplifier to said load. 
     
     
       29. A temperature compensated detector for an input signal, comprising:
   a first conductive line for carrying said input signal;        a second conductive line proximate said first conductive line, said second conductive line for carrying electromagnetically induced signals from said first conductive line, said second conductive line having first and second terminals,        a detector circuit, which includes a first rectifier, for producing an output signal representing the amplitude of said input signal, said detector circuit connected to said first terminal of said second conductive line;        a temperature compensation circuit which includes a current source that provides a DC bias current to a node from which said bias current is divided into first and second currents which flow through respective first and second circuit paths, said second path including a second rectifier;        said first path extending from said node through said second terminal of said second conductive line, said second conductive line, said first terminal of said second conductive line, and said first rectifier of said detector circuit; and        said first path and said second path having substantially equal resistance wherein said first and second currents are substantially equal.     
     
     
       30. The temperature compensated detector of  claim 29  wherein said current source is a temperature compensated constant current source. 
     
     
       31. The temperature compensated detector of  claim 29  wherein said first path includes a first resistor in series with said first rectifier between said node and a common terminal and said second path includes a second resistor in series with said second rectifier between said node and said common terminal. 
     
     
       32. The temperature compensated detector of  claim 31  wherein said detector circuit includes a first capacitor connected in parallel with said first resistor and said temperature compensation circuit includes a second capacitor connected in parallel with said second rectifier. 
     
     
       33. The temperature compensated detector of  claim 29  wherein said first and second rectifiers are matched diodes. 
     
     
       34. The temperature compensated detector of  claim 29  wherein said detector circuit is an RF detector circuit. 
     
     
       35. The temperature compensated detector of  claim 29  wherein said first and second conductive lines are part of a directional coupler. 
     
     
       36. The temperature compensated detector of  claim 29 , further including in combination a wireless transceiver and wherein said temperature compensated detector is coupled between an amplifier, said amplifier providing said input signal, and a load for controlling a power transmitted by said amplifier to said load. 
     
     
       37. A temperature compensated detector for an input signal, comprising:
   a first conductive line for carrying said input signal;        a second conductive line proximate to said first conductive line, said second conductive line for carrying electromagnetically induced signals from said first conductive line, said second conductive line having first and second terminals;        a detector circuit, which includes a first rectifier connected in series with a first resistor between said first terminal of said second conductive line and a common terminal, and a first capacitor connected in parallel with said first resistor, for producing an output signal at a junction node between said first rectifier and        said first capacitor, said output signal representing the amplitude of said input signal;        a temperature compensation circuit which includes a constant current source that provides a DC bias current to a node from which said bias current is divided into first and second currents which flow through respective first and second circuit paths, said second path having a second rectifier connected in series with a second resistor between said node and said common terminal;        said first path extending from said node through said second terminal of said second conductor, said second conductor, said first terminal of said second conductor, said first rectifier and said first resistor of said detector circuit to said common terminal; and        said first path and said second path having substantially equal resistance wherein said first and second currents are substantially equal.     
     
     
       38. The temperature compensated detector of  claim 37  wherein said constant current source is temperature compensated. 
     
     
       39. The temperature compensated detector of  claim 37  wherein said first rectifier is matched to said second rectifier and said first and second resistors have substantially the same resistance. 
     
     
       40. The temperature compensated detector of  claim 37 , further including in combination a wireless transceiver and wherein said temperature compensated detector is coupled between an amplifier, said amplifier providing said input signal, and a load for controlling a power transmitted by said amplifier to said load.