Biasing arrangement for a push-pull amplifier

Claim 2

An amplifier circuit comprising: a first and a second field effect transistor each having source and drain electrodes, a connection between the source electrode of said first transistor and the drain electrode of said second transistor, an output terminal taken out of said connection, input terminals connected to the gates of said transistors, a first resistor connected between gate and one of said electrodes of said first transistor, a second resistor connected between gate and one of said electrodes of said second transistor, a first voltage supply connected to the drain of said first transistor, a second voltage supply connected to the source electrode of said second transistor, and a constant current supplying means including a pair of output adjustable constant current supplying units, each unit having a respective further transistor with a collector electrode connected directly to a respective one of said gates, a base electrode, and an emitter electrode, said constant current supplying means further including a differential balancing potentiometer having an adjustable tap and being connected at opposite ends to said emitters respectively and a manually adjustable third voltage supply connected between said tap on one hand and both of said base electrodes on the other hand for selectively setting manually the operating mode of said first and second field effect transistors by varying the gate biases thereof equally by only adjusting said adjustable third voltage source, the adjustment of said tap being itself operative to balance said gate biases.

Claim 3

An amplifier circuit as in claim 1 wherein each of the said further transistors in said constant current supplying means has substantially infinite impedance for alternating current.

Claim 4

An amplifier circuit comprising: a first and a second field effect transistor each having source and drain electrodes, a connection between the source electrode of said first transistor and the drain electrode of said second transistor, an output terminal taken out of said connection, input terminals connected to the gates of said transistors, a first resistor connected between gate and one of said electrodes of said first transistor, a second resistor connected between gate and one of said electrodes of said second transistor, a first voltage supply connected to the drain of said first transistor, a second voltage supply connected to the source electrode of said second transistor, and constant-current supplying means having two output terminals connected respectively to the gates of said transistors and comprising: a differential amplifier including a third and a fourth transistor each having a collector electrode connected to one of said output terminals of said constant-current supplying means, a base electrode, and an emitter electrode, and an output adjustable constant-current supplying unit including a fifth transistor having a collector electrode connected to said emitters of said third and fourth transistor, an emitter electrode connected through a resistor to a third voltage supply, a base electrode, and a manually adjustable voltage supply to said third voltage supply and base electrode of said fifth transistor for selectively setting manually the operating mode of said first and second field effect transistors by varying the gate biases thereof equally by only adjusting said adjustable voltage source.

Claim 5

An amplifier circuit comprising: a first and a second field effect transistor each having source and drain electrodes, a connection between the source electrode of said first transistor and the drain electrode of said second transistor, an output terminal taken out of said connection, input terminals connected to the gates of said transistors, a first resistor connected between gate and one of said electrodes of said first transistor, a second resistor connected between gate and one of said electrodes of said second transistor, a first voltage supply connected to the drain of said first transistor, a second voltage supply connected to the source electrode of said second transistor, and constant-current supplying means having two output terminals connected respectively to the gates of said transistors and comprising: a differential amplifier including a third and a fourth transistor each having a collector electrode connected to one of said output terminals of said constant-current supplying means, a base electrode, and an emitter electrode, and an output adjustable constant-current supplying unit including a fifth transistor having a collector electrode connected to said emitters of said third and fourth transistor, an emitter electrode connected through a resistor to a third voltage supply, a base electrode, and a manually adjustable voltage supply to said third voltage supply and base electrode of said fifth transistor for selectively setting manually the operating mode of said first and second field effect transistors by varying the gate biases thereof equally by only adjusting said adjustable voltage source.

Claim 6

An amplifier circuit as in claim 1 or 3 wherein adjustment of said manually adjustable voltage supply causes the said operating mode of said first and second transistors to be selectively set for either a class A or class B operation.

Claim 7

An amplifier circuit comprising: a first and a second field effect transistor each having source and drain electrodes, a connection between the source electrode of said first transistor and the drain electrode of said second transistor, an output terminal taken out of said connection, input terminals connected to the gates of said transistors, a first resistor connected between gate and one of said electrodes of said first transistor, a second resistor connected between gate and one of said electrodes of said second transistor, a first voltage supply connected to the drain of said first transistor, a second voltage supply connected to the source electrode of said second transistor, constant-current supplying means having two output terminals connected respectively to the gates of said transistors and comprising: a differential amplifier including a third and a fourth transistor each having a collector electrode connected to one of said output terminals of said constant-current supplying means, a base electrode, and an emitter electrode, and an output adjustable constant-current supplying unit including a fifth transistor having a collector electrode connected to said emitters of said third and fourth transistor, an emitter electrode connected through a resistor to a third voltage supply, and a base electrode connected through an output adjustable voltage supply to said third voltage supply, wherein said output adjustable voltage supply is controlled by a supply-voltage fluctuation detecting means comprising: a sixth transistor having a emitter electrode connected through a fifth resistor to said first voltage supply, a base electrode connected directly to said second voltage supply, and an collector electrode connected through a sixth resistor to said third voltage supply, and said output adjustable voltage supply includes a Zener diode with its anode connected to said third voltage supply, a first diode with its cathode connected to the cathode of said Zener diode and its anode connected through a fourth resistor to the ground, a potentiometer with an end connected to the junction point of said sixth transistor and said sixth resistor, the other end connected to the anode of said first diode, and a sliding tap connected directly to the base electrode of said fifth transistor and through a second diode to the cathode of said Zener diode.

Claim 8

An amplifier circuit comprising: a first and a second field effect transistor each having source and drain electrodes, a connection between the source electrode of said first transistor and the drain electrode of said second transistor, an output terminal taken out of said connection, input terminals connected to the gates of said transistors, a first resistor connected between gate and one of said electrodes of said first transistor, a second resistor connected between gate and one of said electrodes of said second transistor, a first voltage supply connected to the drain of said first transistor, a second voltage supply connected to the source electrode of said second transistor, constant-current supplying means having two output terminals connected respectively to the gates of said transistors and comprising: a differential amplifier including a third and a fourth transistor each having a collector electrode connected to one of said output terminals of said constant-current supplying means, a base electrode, and an emitter electrode, and an output adjustable constant-current supplying unit including a fifth transistor having a collector electrode connected to said emitters of said third and fourth transistor, an emitter electrode connected through a resistor to a third voltage supply, and a base electrode connected through an output adjustable voltage supply to said third voltage supply, wherein said output adjustable voltage supply is controlled by a supply-voltage fluctuation detecting means comprising: a sixth transistor having a emitter electrode connected through a fifth resistor to said first voltage supply, a base electrode connected directly to said second voltage supply, and an collector electrode connected through a sixth resistor to said third voltage supply, and said output adjustable voltage supply includes a Zener diode with its anode connected to said third voltage supply, a first diode with its cathode connected to the cathode of said Zener diode and its anode connected through a fourth resistor to the ground, a potentiometer with an end connected to the junction point of said sixth transistor and said sixth resistor, the other end connected to the anode of said first diode, and a sliding tap connected directly to the base electrode of said fifth transistor and through a second diode to the cathode of said Zener diode.

Claim 9

An amplifier circuit comprising: a first and a second field effect transistor each having source and drain electrodes, a connection between the source electrode of said first transistor and the drain electrode of said second transistor, an output terminal taken out of said connection, input terminals connected to the gates of said transistors, a first resistor connected between gate and one of said electrodes of said first transistor, a second resistor connected between gate and one of said electrodes of said second transistor, a first voltage supply connected to the drain of said first transistor, a second voltage supply connected to the source electrode of said second transistor, constant-current supplying means having two output terminals connected to the gates of said transistors and comprising: a differential amplifier including a third and a fourth transistor each having a collector electrode connected to one of said output terminals of said constant-current supplying means, a base electrode, and an emitter electrode, and an output adjustable constant-current supplying unit including a fifth transistor having a collector electrode connected to said emitters of said third and fourth transistor, an emitter electrode connected through a resistor to a third voltage supply, and a base electrode connected through an output adjustable voltage supply to said third voltage supply, wherein said output adjustable voltage supply is controlled by a supply-voltage fluctuation detecting means comprising: a sixth transistor having an emitter electrode connected through a fifth resistor to ground, a base electrode connected directly to said second voltage supply, and a collector electrode connected through a sixth resistor to said third voltage supply, and said output adjustable voltage supply includes a Zener diode with its anode connected to said third voltage supply, a first diode with its cathode connected to the cathode of said Zener diode and its anode connected through a fourth resistor to ground, a potentiometer with an end connected to the junction point of said sixth transistor and said sixth resistor, the other end connected to the anode of said first diode, and a sliding tap connected directly to the base electrode of said fifth transistor and through a second diode to the cathode of said Zener diode.

Claim 10

An amplifier circuit comprising: a first and a second field effect transistor each having source and drain electrodes, a connection between the source electrode of said first transistor and the drain electrode of said second transistor, an output terminal taken out of said connection, input terminals connected to the gates of said transistors, a first resistor connected between gate and one of said electrodes of said first transistor, a second resistor connected between gate and one of said electrodes of said second transistor, a first voltage supply connected to the drain of said first transistor, a second voltage supply connected to the source electrode of said second transistor, constant-current supplying means having two output terminals connected to the gates of said transistors and comprising: a differential amplifier including a third and a fourth transistor each having a collector electrode connected to one of said output terminals of said constant-current supplying means, a base electrode, and an emitter electrode, and an output adjustable constant-current supplying unit including a fifth transistor having a collector electrode connected to said emitters of said third and fourth transistor, an emitter electrode connected through a resistor to a third voltage supply, and a base electrode connected through an output adjustable voltage supply to said third voltage supply, wherein said output adjustable voltage supply is controlled by a supply-voltage fluctuation detecting means comprising: a sixth transistor having an emitter electrode connected through a fifth resistor to ground, a base electrode connected directly to said second voltage supply, and a collector electrode connected through a sixth resistor to said third voltage supply, and said output adjustable voltage supply includes a Zener diode with its anode connected to said third voltage supply, a first diode with its cathode connected to the cathode of said Zener diode and its anode connected through a fourth resistor to ground, a potentiometer with an end connected to the junction point of said sixth transistor and said sixth resistor, the other end connected to the anode of said first diode, and a sliding tap connected directly to the base electrode of said fifth transistor and through a second diode to the cathode of said Zener diode.