Bidirectional buffered interface for crosspoint switch
AssigneeIntersil Americas Inc.
InventorChristopher Ludeman
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Abstract
A bidirectional crosspoint switch interface employs a pair of backward-connected transimpedance amplifiers of the type disclosed in the U.S. Patent to L. Enriquez, U.S. Pat. No. 6,411,163, and associated scaling current mirrors that drive nodes of associated reverse signal cancellation circuits. The reverse signal cancellation circuits are coupled to respective pairs of ports of the crosspoint switch and input and output ports of 1:1 current mirrors, in a manner that affords bidirectional buffering between the crosspoint switch and a pair of bidirectional signaling ports that terminate respective signaling links, without signal reflections.
Claims15
A bidirectional interface for a bidirectional crosspoint switch comprising a pair of reverse-configured transimpedance amplifiers, having input/output ports thereof coupled to bidirectional signaling ports that are adapted to be coupled to respective communication lines, and having current mirror outputs thereof interconnected to ports of said bidirectional crosspoint switch via associated signal cancellation circuits, providing bidirectional buffering between said bidirectional crosspoint switch and said bidirectional signaling ports without signal reflections.
A bidirectional interface for a bidirectional crosspoint switch comprising:
- first and second transimpedance amplifier circuits, each of which includes
- an operational amplifier having first and second input nodes, and an output node, said operational amplifier having a gain stage cascaded with an output stage, said gain stage having an inverting input coupled to said first input node, and a non-inverting input coupled to said second input node, said output stage having an output thereof coupled to said output node, said output of said output stage being coupled by way of a feedback path to said inverting input of said gain stage, and
- a first current mirror coupled to a first voltage supply, and having a first current mirror input port coupled to said output stage, and a first current mirror output port coupled to an output port of a second current mirror, said second current mirror having an input port coupled through a scaling impedance to said non-inverting input of said operational amplifier;
- a bidirectional crosspoint switch having first, second, third and fourth ports, and being adapted to interconnect said first and second ports thereof with said third and fourth ports thereof;
- and wherein
- said first port of said crosspoint switch is coupled to said output port of said first current mirror of said first transimpedance amplifier circuit,
- said second port of said crosspoint switch is coupled to said non-inverting input of said operational amplifier of said first transimpedance amplifier circuit,
- said third port of said crosspoint switch is coupled to said output port of said first current mirror of said second transimpedance amplifier circuit,
- said fourth port of said crosspoint switch is coupled to said non-inverting input of said operational amplifier of said second transimpedance amplifier circuit,
- a first bidirectional signaling port coupled to the output node of said first transimpedance amplifier circuit;
- and
- a second bidirectional signaling port coupled to the output node of said second transimpedance amplifier circuit.
A bidirectional interface for providing bidirectional connectivity between a first bidirectional signaling port that is adapted to be coupled to a first bidirectional signaling link, and a second bidirectional signaling port that is adapted to be coupled to a second bidirectional signaling link, said interface comprising:
- a four-port bidirectional crosspoint switch, having a first pair of ports thereof cross-coupled to a second pair of ports thereof;
- a first buffer stage that includes
- a first, reverse-configured transimpedance amplifier circuit, having an input/output port coupled to said first bidirectional signaling port, an output stage coupled to a first scaling current mirror, which has an output thereof coupled to a first port of said first pair of ports of said four-port bidirectional crosspoint switch, and an input stage coupled to a second port of said first pair of ports of said four-port bidirectional crosspoint switch, and
- a first reflected signal cancellation stage coupled to said first and second ports of said first pair of ports of said four-port bidirectional crosspoint switch;
- and
- a second buffer stage that includes
- a second, reverse-configured transimpedance amplifier circuit, having an input/output port coupled to said second bidirectional signaling port, an output stage coupled to a second scaling current mirror, which has an output thereof coupled to a first port of said second pair of ports of said four-port bidirectional crosspoint switch, and an input stage coupled to a second port of said second pair of ports of said four-port bidirectional crosspoint switch, and
- a second reflected signal cancellation stage coupled to said first and second ports of said second pair of ports of said four-port bidirectional crosspoint switch.
Dependencies are inferred from the claim text.