Temperature responsive circuit for protecting an electron device

Claim 2

A control circuit for controlling an amplifier including an electron device and a heat dissipating structure associated with the device in response the temperature of the heat dissipating structure and the ambient temperature, the temperature of the device depending on the magnitude of a bias level applied to the amplifier, such control circuit including in combinAtion: a normally nonconductive device having first, second and third electrodes and being rendered conductive in response to a control voltage of a given magnitude applied to said second electrode; first circuit means applying a supply voltage to said first electrode of said device; second circuit means coupling said third electrode of said normally nonconductive device to the amplifier; first temperature sensitive resistance means having first and second ends and a body which is thermally connected to the heat dissipating structure associated with the electron device for sensing the temperature thereof; third circuit means applying said supply voltage to said first end of said first temperature sensitive resistance means, second temperature sensitive resistance means having a body positioned to sense the ambient temperature, a first and connected to said second end of said first temperature sensitive resistance means and a second end connected to a reference potential; fourth circuit means connecting said first end of said second temperature sensitive resistance means to said second electrode of said normally nonconductive electron device; and said first and second temperature sensitive resistance means cooperating to develop a control voltage across said second temperature sensitive resistance means, said normally nonconductive electron device being rendered conductive by said control voltage exceeding a given magnitude to apply a portion of said supply voltage to the amplifier to change said bias level to thereby control the temperature of the electron control device.

Claim 3

The control circuit of claim 1 wherein said normally nonconductive device is a silicon controlled rectifier, and said first, second and third electrodes are respectively the anode, gate and cathode thereof.

Claim 4

The control circuit of claim 1 wherein said first circuit means includes a power supply providing a supply voltage at its output and a potentiometer connected between said output of said power supply and said first electrode of said normally nonconductive device.

Claim 5

The control circuit of claim 1 wherein said second circuit means includes a diode having first and second terminals, said first terminal of said diode being connected to said third electrode of said normally nonconductive device and said second terminal of said diode being connected to the amplifier, said diode isolating said third electrode of said normally conductive device from changes in the bias level occurring in the amplifier.

Claim 6

The control circuit of claim 1 wherein said first and second temperature sensitive resistance means are respectively first and second thermistors each having negative temperature coefficients, said second thermistor having more thermal capacity than said first thermistor.

Claim 7

The control circuit of claim 1 wherein said fourth circuit means includes a resistor means having a first end connected to said first end of said second temperature sensitive resistance means and a second end; filter capacitor means having a first plate connected to said reference potential and a second plate connected both to said second end of said resistor means and to said second electrode of said normally nonconductive electron device; and said resistor means and filter capacitor means suppressing transients possibly occurring at said first end of said second temperature sensitive resistance means so that said transients cannot render said normally nonconductive device conductive.

Claim 8

In a radio frequency amplifier having first and second cascaded stages wherein the temperature of the electron control device of the second stage varies with a bias potential developed across a component of the first stage, the electron control device of the second stage having a heat dissipating structure associated therewith, a control circuit for controlling the temperature of the electron control device of the second stage including in combination: normally nonconducTive device having first, second and third electrodes and being rendered conductive in response to control voltage of a given magnitude applied to its second electrode; power supply means providing a supply voltage at its output; first circuit means connected from said output of said power supply means to said first electrode of said normally nonconductive device; second circuit means coupling said third electrode of said normally nonconductive device to the component of the first stage; first temperature sensitive resistive means having first and second ends and a body which is thermally connected to and senses the temperature of the heat dissipating structure associated with the electron control device of the second stage, said first end of said first temperature resistive means being connected to said output of said power supply means; second temperature sensitive resistive means having a body positioned to sense the ambient temperature near the heat dissipating structure, a first end connected to said second end of said first temperature sensitive resistive means and a second end connected to a reference potential; third circuit means connecting said first end of said second temperature sensitive resistive means to said second electrode of said normally nonconductive device; said first and second temperature sensitive resistive means cooperating to develop said control voltage across said second temperature sensitive resistive means, said normally nonconductive device being rendered conductive by said control voltage exceeding said magnitude to apply a portion of said supply voltage to the component thereby changing the bias potential, the temperature of the electron control device of the second stage changing in response to said change in the bias potential.

Claim 9

In a radio frequency amplifier having first and second cascaded stages wherein the temperature of the electron control device of the second stage varies with a bias potential developed across a component of the first stage, the electron control device of the second stage having a heat dissipating structure associated therewith, a control circuit for controlling the temperature of the electron control device of the second stage including in combination: normally nonconducTive device having first, second and third electrodes and being rendered conductive in response to control voltage of a given magnitude applied to its second electrode; power supply means providing a supply voltage at its output; first circuit means connected from said output of said power supply means to said first electrode of said normally nonconductive device; second circuit means coupling said third electrode of said normally nonconductive device to the component of the first stage; first temperature sensitive resistive means having first and second ends and a body which is thermally connected to and senses the temperature of the heat dissipating structure associated with the electron control device of the second stage, said first end of said first temperature resistive means being connected to said output of said power supply means; second temperature sensitive resistive means having a body positioned to sense the ambient temperature near the heat dissipating structure, a first end connected to said second end of said first temperature sensitive resistive means and a second end connected to a reference potential; third circuit means connecting said first end of said second temperature sensitive resistive means to said second electrode of said normally nonconductive device; said first and second temperature sensitive resistive means cooperating to develop said control voltage across said second temperature sensitive resistive means, said normally nonconductive device being rendered conductive by said control voltage exceeding said magnitude to apply a portion of said supply voltage to the component thereby changing the bias potential, the temperature of the electron control device of the second stage changing in response to said change in the bias potential.

Claim 10

The combination of claim 7 wherein said first circuit means includes a potentiometer having an adjustable resistance, said resistance being adjusted so that the bias potential across the component shifts a predetermined amount in response to said normally nonconductive device being rendered conductive.

Claim 11

The combination of claim 7 wherein said normally nonconductive device is a silicon controlled rectifier, and said first, second and third electrodes are respectively the anode, gate and cathode thereof.

Claim 12

The combination of claim 9 wherein said first circuit means includes a switch means for interrupting the current flow through said silicon controlled rectifier so that said silicon controlled rectifier can be reset to its nonconductive state after it has been rendered conductive and after the temperature of the electron control device of the second stage has decreased.