Universal input apparatus
AssigneeMicrel, Inc.
InventorsThomas S. Wong, Stephen J. B. Pratt
Life of this patent
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Abstract
Input structures and topologies are provided for coupling a differential input into a first stage of a circuit, topology, or device. An input pin is coupled to an impedance divider that translates an input voltage to accommodate low input voltage levels, while not saturating an input differential pair. A termination pair with a center tap pin is further coupled to the input pins. The center tap facilitates coupling different termination configurations to the input signal. The topologies accommodate packaged devices that have at least three external pins, two pins for the coupling of a differential input signal, and a pin for the termination pair center tap.
Claims17
A method for coupling an input signal to a circuit, said method comprising
- receiving an input signal according to a first voltage standard;
- establishing a circuit input voltage proportional to the voltage of said input signal using a voltage divider;
- and
- coupling a center tap pin to a reference node, thereby terminating said input signal, wherein said reference node is chosen based on said first voltage standard.
A method for coupling a differential output signal comprising according to a first logic standard to a circuit, said method comprising:
- providing an integrated circuit comprising:
- a first voltage divider having a first intermediate node and a second voltage divider having a second intermediate node;
- and
- a termination pair comprising a first and second resistor, wherein said first resistor is coupled to said first voltage divider and said second resistor is coupled to said second voltage divider;
- and
- a center pin coupled to said first and second resistor;
- coupling said differential output signal to said first and second intermediate nodes;
- and
- coupling said center pin to a reference node, wherein the voltage at said reference node is chosen based on said logic standard.
A packaged integrated circuit comprising:
- an integrated circuit comprising:
- a first voltage divider having a first intermediate node and a second voltage divider having a second intermediate node;
- and
- a termination pair comprising a first and second resistor, wherein said first resistor is coupled to said first voltage divider and said second resistor is coupled to said second voltage divider;
- and
- a package comprising said integrated circuit and
- a first input pin coupled to said first voltage divider;
- a second input pin coupled to said second voltage divider;
- and
- a third input pin coupled to said first and second resistor.
Dependencies are inferred from the claim text.