Rf amplifier control system

Claim 2

RF circuit apparatus including in combination RF circuit means having an input connection, an output connection, and a DC power connection for applying operating voltage thereto; an input terminal; variable RF impedance means connected in series between the input terminal and the input connection of the RF circuit means, the value of the RF impedance of the variable RF impedance means being inversely related to the DC current passing therethrough; a source of DC voltage; and switching means including first transistor means connected between said source of DC voltage and said DC power connection of the RF circuit means and having a control input connection connected thereto, said first transistor means being operable in a conducting condition in response to a first input condition being present at said control input connection thereby permitting said source of DC voltage to supply operating voltage to said RF circuit means, and being operable in a nonconducting condition in response to a second input condition being present at said control input connection thereby preventing said source of DC voltage from supplying operating voltage to said RF circuit means; and second transistor means connected between said first transistor means and said variable RF impedance means, said second transistor means being operable in a conducting condition when said first transistor means is in a conducting condition thereby permitting DC current to flow through said variable RF impedance means, and being operable in a nonconducting condition when said first transistor means is in a nonconducting condition thereby preventing DC current from flowing through said variable RF impedance means; whereby said RF circuit means is activated and a low RF impedance is produced at the input thereto in response to the first input condition at said switching means, and said RF circuit means is inactivated and a high RF impedance is produced at the input thereto in response to the second input condition at said switching means.

Claim 3

Apparatus in accordance with claim 1 wherein said variable RF impedance means includes a semiconductor diode; and including first input circuit means connected between the input terminal and the semiconductor diode for permitting the flow of RF current from the input terminal to the semiconductor diode and for preventing the flow of DC current from the source of DC voltage to the input terminal; and second input circuit means connected between the semiconductor diode and the second transistor means for permitting the flow of DC current from the second transistor means to the semiconductor diode and for preventing the flow of RF current from the input terminal to the second transistor means.

Claim 4

Apparatus in accordance with claim 2 wherein said first transistor means includes a first transistor of one conductivity type having its collector connected to said source of DC voltage, its base connected to said control input connection, and its emitter connected to the DC power connection of the RF circuit means; and said second transistor means includes a second transistor of the opposite conductivity type having its emitter connected to the emitter of the first transistor and its collector connected to the semiconductor diode.

Claim 5

Apparatus in accordance with claim 3 wherein said RF circuit means includes an RF amplifier; and including biasing control means connected to the base of said second transistor and operable to vary the current through the second transistor when the second transistor is in a conducting condition thereby varying the RF impedance between the input terminal and the input connection of the RF circuit means.

Claim 6

Apparatus in accordance with claim 1 including biasing control means connected to said second transistor means and operable to vary the current through the second transistor means when the second transistor means is in a conducting condition thereby varying the RF impedance of the variable RF impedance means.

Claim 7

An RF amplifier control system including in combination first RF amplifier means having an input connection, an output connection, and a DC power connection for applying operating voltage thereto; second RF amplifier means having an input connection, an output connection, and a DC power connection for applying operating voltage thereto; an input terminal; first variable RF impedance means connected in series between the input terminal and the input connection of the first RF amplifier means; second variable RF impedance means connected in series between the input terminal and the input connection of the second RF amplifier means; the value of the RF impedance of each of the variable RF impedance means being inversely related to the DC current passing therethrough; a source of DC voltage; first switching means having a control input connection and being connected to said source of DC voltage, to said DC power connection of the first RF amplifier means, and to the first variable RF impedance means; second switching means having a control input connection and being connected to said source of DC voltage, to said DC power connection of the second RF amplifier means, and to said second variable RF impedance means; said first and second switching means each including a first transistor means connected between said source of DC voltage and said DC power connection of the associated RF amplifier means and having said associated control input connection connected thereto, a first transistor means being operable in a conducting condition in response to a first input condition being present at the associated control input connection thereby permitting said source of DC voltage to supply operating voltage to the associated RF amplifier means activating the RF amplifier means, and being operable in a nonconducting condition in response to a second input condition being present at the associated control input connection thereby preventing said source of DC voltage from supplying operating voltage to the associated RF amplifier means inactivating the RF amplifier means; a second transistor means connected between said first transistor means and the associated variable RF impedance means, a second transistor means bEing operable in a conducting condition when the associated first transistor means is in a conducting condition thereby permitting DC current to flow through the associated variable RF impedance means producing a low impedance at the input to the associated RF amplifier means, and being operable in a nonconducting condition when said first transistor means is in a nonconducting condition thereby preventing DC current from flowing through the associated variable RF impedance means and producing a high RF impedance at the input to the associated RF amplifier means; additional circuit means; and signal coupling means connected to the output connection of the first RF amplifier means, the output connection of the second RF amplifier means, and to the additional circuit means, said signal coupling means being operable when said first RF amplifier means is activated and said second RF amplifier means is inactivated to couple output signals from said first RF amplifier means to said additional circuit means, and operable when said first RF amplifier means is inactivated and said second amplifier means is activated to couple output signals from said second RF amplifier means to said additional circuit means.

Claim 8

An RF amplifier control system including in combination first RF amplifier means having an input connection, an output connection, and a DC power connection for applying operating voltage thereto; second RF amplifier means having an input connection, an output connection, and a DC power connection for applying operating voltage thereto; an input terminal; first variable RF impedance means connected in series between the input terminal and the input connection of the first RF amplifier means; second variable RF impedance means connected in series between the input terminal and the input connection of the second RF amplifier means; the value of the RF impedance of each of the variable RF impedance means being inversely related to the DC current passing therethrough; a source of DC voltage; first switching means having a control input connection and being connected to said source of DC voltage, to said DC power connection of the first RF amplifier means, and to the first variable RF impedance means; second switching means having a control input connection and being connected to said source of DC voltage, to said DC power connection of the second RF amplifier means, and to said second variable RF impedance means; said first and second switching means each including a first transistor means connected between said source of DC voltage and said DC power connection of the associated RF amplifier means and having said associated control input connection connected thereto, a first transistor means being operable in a conducting condition in response to a first input condition being present at the associated control input connection thereby permitting said source of DC voltage to supply operating voltage to the associated RF amplifier means activating the RF amplifier means, and being operable in a nonconducting condition in response to a second input condition being present at the associated control input connection thereby preventing said source of DC voltage from supplying operating voltage to the associated RF amplifier means inactivating the RF amplifier means; a second transistor means connected between said first transistor means and the associated variable RF impedance means, a second transistor means bEing operable in a conducting condition when the associated first transistor means is in a conducting condition thereby permitting DC current to flow through the associated variable RF impedance means producing a low impedance at the input to the associated RF amplifier means, and being operable in a nonconducting condition when said first transistor means is in a nonconducting condition thereby preventing DC current from flowing through the associated variable RF impedance means and producing a high RF impedance at the input to the associated RF amplifier means; additional circuit means; and signal coupling means connected to the output connection of the first RF amplifier means, the output connection of the second RF amplifier means, and to the additional circuit means, said signal coupling means being operable when said first RF amplifier means is activated and said second RF amplifier means is inactivated to couple output signals from said first RF amplifier means to said additional circuit means, and operable when said first RF amplifier means is inactivated and said second amplifier means is activated to couple output signals from said second RF amplifier means to said additional circuit means.

Claim 9

A system in accordance with claim 6 wherein said first variable RF impedance means includes a first semiconductor diode; said second variable RF impedance means includes a second semiconductor diode; and including a first input circuit means connected between the input terminal and the first semiconductor diode for permitting the flow of RF current from the input terminal to the first semiconductor diode and for preventing the flow of DC current from the source of DC voltage to the input terminal by way of the first switching means; a second input circuit means connected between the first semiconductor diode and the second transistor means of the first switching means for permitting the flow of DC current from the second transistor means to the first semiconductor diode and for preventing the flow of RF current from the input terminal to the second transistor means; another first input circuit means connected between the input terminal and the second semiconductor diode for permitting the flow of RF current from the input terminal to the second semiconductor diode and for preventing the flow of DC current from the source of DC voltage to the input terminal by way of the second switching means; and another second input circuit means connected between the second semiconductor diode and the second transistor means of the second switching means for permitting the flow of DC current from the second transistor means to the second semiconductor diode and for preventing the flow of RF current from the input terminal to the second transistor means.

Claim 10

A system in accordance with claim 7 wherein said first transistor means of the first switching means includes a first transistor of one conductivity type having its collector connected to said source of DC voltage, its base connected to the control input connection of the first switching means, and its emitter connected to the DC power connection of the first RF amplifier means; said second transistor means of the first switching means includes a second transistor of the opposite conductivity type having its emitter connected to the emitter of the first transistor and its collector connected to the first semiconductor diode; said first transistor means of the second switching means includes a first transistor of the one conductivity type having its collector connected to said source of DC voltage, its base connected to the control input connection of the second switching means, and its emitter connected to the DC power connection of the second RF amplifier means; and said second transistor means of the second switching means includes a second transistor of the opposite conductivity Type having its emitter connected to the emitter of the first transistor and its collector connected to the second semiconductor diode.

Claim 11

A system in accordance with claim 8 wherein said first RF amplifier means includes a tuned output circuit having an inductance coupled to a point of reference potential; said second RF amplifier means includes a tuned output circuit having an inductance coupled to said point of reference potential; and said signal coupling means includes a transformer having a primary winding with one terminal connected intermediate the ends of the inductance in the tuned output circuit of the first RF amplifier means and with the other terminal connected intermediate the ends of the inductance in the tuned output circuit of the second RF amplifier means.

Claim 12

A system in accordance with claim 9 wherein said additional circuit means includes an amplifier having an output connection; and including biasing control means connected to the base of the second transistor of the first switching means and to the base of the second transistor of the second switching means, said biasing control means being operable to vary the current through a second transistor when a second transistor is in a conducting condition thereby varying the RF impedance between the input terminal and the input connection of the associated RF amplifier means; feedback means connected to the output connection of the amplifier of said additional circuit means and to said biasing control means and operable when the output of the amplifier exceeds a predetermined level to cause the biasing control means connected to a second transistor in a conducting condition to decrease current flow therethrough thereby increasing the RF impedance of the associated semiconductor diode.

Claim 13

A system in accordance with claim 6 including biasing control means connected to the second transistor means of the first switching means and to the second transistor means of the second switching means, said biasing control means being operable to vary the current through a second transistor means when a second transistor means is in a conducting condition thereby varying the RF impedance of the associated variable RF impedance means.