Device and method for bi-directional amplification with a JFET

Claim 1

A bi-directional amplifier system for a radio-frequency transceiver in which radio frequency signals propagate in a first direction through the amplifier when the transceiver is transmitting and propagate in the opposite direction when the transceiver is receiving, comprising: (a) a channel-type amplifying device having a grounded gate and two junctions for amplifying a voltage related to a signal received at one of the junctions; (b) two impedance circuits, one electrically connected to each of the junctions, for providing a relatively low impedance at a selected one of said junctions and for providing a relatively high impedance at the other of said junctions, each of said impedance circuits comprising, (1) resistance means connected electrically in parallel between one of said junctions and a ground reference, (2) parallel capacitance means connected electrically in parallel to said resistance means, (3) an L-matching network circuit electrically connected to said one of said junctions, said L-matching network circuit comprising, an inductor electrically in parallel to said resistance means, a series capacitor electrically in series between said one of said junctions and a terminal of the amplifier system, and a switch connected to shunt said series capacitor, (4) a low Q impedance matching network circuit electrically connected in series between said L-matching network and said terminal, said low Q impedance matching network circuit comprising, an inductor electrically connected in parallel to said resistance means, a capacitor electrically connected in series between said L-matching network and said terminal, and (5) a switched supply of power electrically connected to supply said power to one of said junctions, and (c) logic means to selectively operate one of the impedance circuits to provide a relatively low impedance at the terminal transmitting the signal to be transmitted.

Claim 13

A device for alternatively amplifying two signals having different frequencies flowing in opposite directions through said device comprising: two tanks, each for providing one of said two signals, each of said two tanks having tuning means for tuning its frequency; and a bi-directional amplifier connected between said two tanks for ampliyifng said signals, said bi-directional amplifier having a JFET, and means for varying the impedance at each of said JFET's two junctions, whereby each of said tanks may be tuned independently of the other and whereby said bi-directional amplifier amplifies signals having one frequency in one direction and signals having another frequency in the other direction.

Claim 14

A device for alternatively amplifying two signals having different frequencies flowing in opposite directions through said device comprising: two tanks, each for providing one of said two signals, each of said two tanks having tuning means for tuning its frequency; and a bi-directional amplifier connected between said two tanks for ampliyifng said signals, said bi-directional amplifier having a JFET, and means for varying the impedance at each of said JFET's two junctions, whereby each of said tanks may be tuned independently of the other and whereby said bi-directional amplifier amplifies signals having one frequency in one direction and signals having another frequency in the other direction.

Claim 15

A method of amplifying a signal flowing in one direction through a transceiver when the transceiver is transmitting and in the opposite direction when the transceiver is receiving comprising the steps of: (a) applying a biasing voltage to a JFET so that current flows in one direction between the two junctions of said JFET when the transceiver is transmitting and in the opposite direction when the transceiver is receiving; and (b) varying the impedance at said two junctions so that the impedance is relatively low at the one of said junctions from which the current is flowing and relatively high at the other said junction.

Claim 16

A method of amplifying a signal flowing in one direction through a transceiver when the transceiver is transmitting and in the opposite direction when the transceiver is receiving comprising the steps of: (a) applying a biasing voltage to a JFET so that current flows in one direction between the two junctions of said JFET when the transceiver is transmitting and in the opposite direction when the transceiver is receiving; and (b) varying the impedance at said two junctions so that the impedance is relatively low at the one of said junctions from which the current is flowing and relatively high at the other said junction.

Claim 17

A method for amplifying a signal flowing in either direction through a transceiver comprising the steps of: (a) providing a JFET; (b) varying the capacitance at the two junctions of said JFET responsive to the signal direction by inserting or removing capacitor means in series with loads connected to said junctions; and (c) varying the direction of current flow between said junctions responsive to the signal direction by applying a biasing voltage to the one of said junctions to which the current is flowing.

Claim 18

A method for amplifying a signal flowing in either direction through a transceiver comprising the steps of: (a) providing a JFET; (b) varying the capacitance at the two junctions of said JFET responsive to the signal direction by inserting or removing capacitor means in series with loads connected to said junctions; and (c) varying the direction of current flow between said junctions responsive to the signal direction by applying a biasing voltage to the one of said junctions to which the current is flowing.