Method and apparatus for signal reception using ground termination and/or non-ground termination

A method for receiving ground-terminated signals, the method comprising:

• receiving a signal at one or more nodes that provide a grounded termination, the signal associated with a voltage level;
• shifting the voltage level that is associated with the signal upwards to produce a level-shifted signal;
• pre-amplifying the level-shifted signal to produce a processed signal that has been shifted and pre-amplified;
• and
• recovering data encoded into the signal using the processed signal.

An integrated circuit (IC) chip comprising:

• a first input and a second input that are capable of providing ground termination for a differential signal;
• data recovery circuitry that is coupled to a first node and a second node;
• a level shifter coupled to the first input and the second input, the level shifter adapted to accept the differential signal from the first input and the second input and to raise a common mode voltage of the differential signal to produce a level-shifted differential signal;
• and
• a pre-amplifier that is coupled to the first node and the second node, the pre-amplifier adapted to pre-amplify the level-shifted differential signal to produce level-shifted and pre-amplified differential signal that is output at the first node and the second node;
• wherein the data recovery circuitry is adapted to recover data from the level-shifted and pre-amplified differential signal that is received at the first node and the second node.

An apparatus comprising:

• a first input node and a second input node that are capable of providing ground termination for differential signals, the differential signals including encoded data;
• a first current source connected in series with a first transistor between a supply voltage and a common potential, the first input node coupled to a gate terminal of the first transistor, a first node located between the first current source and the first transistor;
• a second current source connected in series with a second transistor between the supply voltage and the common potential, the second input node coupled to a gate terminal of the second transistor, a second node located between the second current source and the second transistor;
• a pre-amplifier that is coupled to the first node and the second node at an input of the pre-amplifier and to a third node and a fourth node at an output of the pre-amplifier, the pre-amplifier adapted to pre-amplify differential signals present at the first node and the second node and to provide differential signals that have been pre-amplified at the third node and the fourth node;
• and
• data recovery circuitry coupled to the third node and the fourth node, the data recovery circuitry adapted to accept differential signals that are present at the third node and the fourth node and to output data encoded therein.

An arrangement comprising:

• signal receiving means for receiving a differential signal with ground termination;
• voltage shifting means for increasing a common mode voltage level that is associated with the differential signal to produce a shifted differential signal;
• and
• data recovery means for recovering data that is encoded into the differential signal using the shifted differential signal.

An apparatus comprising:

• signal input receiver circuitry that is adapted to receive signals according to a ground termination mode and a non-ground termination mode, the signal input receiver circuitry including:
• a first signal input and a second signal input that are capable of receiving at least one signal;
• data recovery circuitry that is capable of recovering data from the at least one received signal;
• a plurality of switches;
• and
• at least one mode input that is capable of selecting between the ground termination mode and the non-ground termination mode;
• wherein selection of the ground termination mode causes the plurality of switches to be in a first configuration that results in the first signal input and the second signal input providing a grounded termination for the at least one received signal and selection of the non-ground termination mode causes the plurality of switches to be in a second configuration that results in the first signal input and the second signal input providing a non-ground termination for the at least one received signal.

A receiving unit comprising:

• a first input node and a second input node that are capable of receiving ground terminated signals in accordance with a first mode and non-ground terminated signals in accordance with a second mode;
• a first switched voltage divider coupled to the first input node, the first switched voltage divider capable of being switched into operation to provide a non-ground termination in accordance with the second mode and out of operation to permit a ground termination in accordance with the first mode;
• a second switched voltage divider coupled to the second input node, the second switched voltage divider capable of being switched into operation to provide a non-ground termination in accordance with the second mode and out of operation to permit a ground termination in accordance with the first mode;
• a level shifter coupled to the first input node and the second input node, the level shifter adapted to shift voltage levels of the ground terminated signals that are present at the first input node and the second input node to produce level-shifted signals;
• a mode select input for selecting between the first mode and the second mode;
• and
• data recovery circuitry that is adapted to recover data from signals that are input thereto;
• wherein the data recovery circuitry is provided at least a version of the level-shifted signals for the first mode and at least a version of the non-ground terminated signals for the second mode responsive to the mode select input.

A receiving unit comprising:

• a first input node and a second input node that are capable of receiving ground terminated signals in accordance with a first mode and non-ground terminated signals in accordance with a second mode;
• a switched voltage divider coupled to the first and second input nodes, the switched voltage divider capable of being switched into operation to provide a non-ground termination in accordance with the second mode and switched out of operation to permit a ground termination in accordance with the first mode;
• a level shifter coupled to the first input node and the second input node, the level shifter adapted to shift voltage levels of the ground terminated signals that are present at the first input node and the second input node to produce level-shifted signals;
• a mode select input for selecting between the first mode and the second mode;
• and
• data recovery circuitry that is adapted to recover data from signals that are input thereto;
• wherein the data recovery circuitry is provided at least a version of the level-shifted signals for the first mode and at least a version of the non-ground terminated signals for the second mode responsive to the mode select input.

An apparatus comprising:

• a first input node and a second input node that are capable of receiving differential signals;
• data recovery circuitry that is capable of recovering data from the differential signals;
• at least one switched voltage divider that is coupled to at least one of the first input node and the second input node, the at least one switched voltage divider adapted to provide a termination voltage that is above ground at the first and second input nodes when activated;
• a level shifter connected between the first and second input nodes and the data recovery circuitry, the level shifter adapted to raise common mode voltages of the differential signals to produce level-shifted differential signals;
• a mode select input that enables initiation of a ground termination mode and a non-ground termination mode;
• wherein:
• initiation of the ground termination mode causes:
• the at least one switched voltage divider to be deactivated,
• a ground termination to be created at the first and second input nodes, and
• the level shifter to forward toward to the data recovery circuitry the level-shifted differential signals;
• and
• initiation of the non-ground termination mode causes:
• the at least one switched voltage divider to be activated,
• a non-ground termination to be created at the first and second input nodes, and
• the level shifter to be bypassed.

A method for operating a receiving unit in at least two modes, the method comprising:

• receiving a differential signal at two input nodes;
• determining whether a ground termination mode or a non-ground termination mode is initiated based on a mode select input;
• if the ground termination mode is initiated, then:
• de-activating at least one switched voltage divider;
• level shifting the differential signal to increase a common mode of the differential signal and to produce a level-shifted differential signal;
• and
• recovering data that is encoded into the differential signal using the level-shifted differential signal;
• and
• if the non-ground termination mode is initiated, then:
• activating at least one switched voltage divider to establish a termination voltage at the two input nodes that is above ground;
• and
• recovering data that is encoded into the differential signal.

An arrangement comprising:

• signal receiving means for receiving a differential signal at a selectable termination level;
• establishment means for establishing a voltage level that is above ground for the selectable termination level;
• shifting means for level shifting the differential signal;
• data recovery means for recovering data that is encoded into the differential signal;
• and
• mode selection means for selecting between a first mode and a second mode;
• wherein selection of the first mode results in the establishment means being inactivated and the data recovery means recovering the data from the differential signal after level shifting by the shifting means, and selection of the second mode results in the establishment means being activated and the data recovery means recovering the data from the differential signal without level shifting by the shifting means.

An apparatus comprising:

• signal input receiver circuitry that receives input signals according to a selectable termination mode, the signal input receiver circuitry including:
• a signal input that receives the input signals;
• and
• a mode select input that receives a mode signal for selecting the selectable termination mode;
• wherein a termination voltage level of the signal input receiver circuitry is set to a first level when a first termination mode is selected and the termination voltage level of the signal input receiver circuitry is set to a second level when a second termination mode is selected.

A receiving unit comprising:

• a first input node and a second input node that are capable of receiving signals terminated at a first termination level in accordance with a first mode and signals terminated at a second termination level in accordance with a second mode;
• a first switched voltage divider coupled to the first input node, the first switched voltage divider capable of being activated to provide termination at the second termination level in accordance with the second mode and deactivated to permit termination at the first termination level in accordance with the first mode;
• a second switched voltage divider coupled to the second input node, the second switched voltage divider capable of being activated to provide termination at the second termination level in accordance with the second mode and deactivated to permit termination at the first termination level in accordance with the first mode;
• a level shifter coupled to the first input node and the second input node, the level shifter adapted to shift voltage levels of the signals terminated at the first termination level that are present at the first input node and the second input node to produce level-shifted signals;
• and
• a mode select input for selecting between the first mode and the second mode.

A receiving unit comprising:

• a first input node and a second input node that are capable of receiving signals terminated at a first termination level in accordance with a first mode and signals terminated at a second termination level in accordance with a second mode;
• a switched voltage divider coupled to the first and second input nodes, the switched voltage divider capable of being activated to provide the second termination level in accordance with the second mode and deactivated to permit the first termination level in accordance with the first mode;
• a level shifter coupled to the first input node and the second input node, the level shifter adapted to shift voltage levels of the signals terminated at the first termination level that are present at the first input node and the second input node to produce level-shifted signals;
• and
• a mode select input for selecting between the first mode and the second mode.

An apparatus comprising:

• a first input node and a second input node that are capable of receiving differential signals at a first termination level and at a second termination level;
• data recovery circuitry that is capable of recovering data from the differential signals;
• at least one switched voltage divider that is coupled to at least one of the first input node and the second input node, the at least one switched voltage divider adapted to provide a termination voltage at the second termination level at the first and second input nodes when activated;
• a level shifter connected between the first and second input nodes and the data recovery circuitry, the level shifter adapted to raise common mode voltages of the differential signals to produce level-shifted differential signals;
• a mode select input that enables initiation of a first termination mode and a second termination mode;
• wherein:
• initiation of the first termination mode causes:
• the at least one switched voltage divider to be deactivated,
• a termination voltage at the first termination level to be created at the first and second input nodes, and
• the level shifter to forward toward the data recovery circuitry the level-shifted differential signals;
• and
• initiation of the second termination mode causes:
• the at least one switched voltage divider to be activated,
• a termination voltage at the second termination level to be created at the first and second input nodes, and
• the level shifter to be bypassed.