Low-power voltage mode high speed driver
AssigneeTexas Instruments Incorporated
InventorsTonmoy Shankar Mukherjee, Arlo Jame Aude
Life of this patent
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Abstract
Differential voltage mode signal driver circuitry is presented in which a differential current mode amplifier input stage provides a differential signal, and an output stage includes a pair of bipolar transistors receiving the differential signal and being connected in series with a pair of cross-coupled field effect transistors that are coupled to corresponding current sources, where a negative impedance circuit is connected between the field effect transistors to substantially cancel a parasitic capacitance of a driven output circuit.
Claims20
A signal driver apparatus, comprising:
- an input circuit comprising first and second transistors forming a current mode amplifier with corresponding first and second control terminals coupled to receive a differential input signal from corresponding first and second driver input terminals, and corresponding first and second output terminals coupled to provide a differential current mode amplifier output signal to first and second current mode amplifier output nodes;
- and
- a driver output circuit comprising:
- a first circuit branch, including a third transistor connected between a power supply node and a first node and including a third control terminal coupled with the first current mode amplifier output node, a first resistor connected between the first node and a first driver output terminal, a fourth transistor coupled between the first driver output terminal and a second node and including a fourth control terminal, and a first current source coupled between the second node and a ground node,
- a second circuit branch, including a fifth transistor coupled between the power supply node and a third node and including a fifth control terminal coupled with the second current mode amplifier output node, a second resistor connected between the third node and a second driver output terminal, a sixth transistor coupled between the second driver output terminal and a fourth node and including a sixth control terminal coupled with the first node, and a second current source coupled between the fourth node and the ground node, wherein the fourth control terminal of the fourth transistor is coupled with the third node, and
- an RC impedance circuit connected between the second node of the first circuit branch and the fourth node of the second circuit branch.
A signal driver, comprising:
- a differential current mode amplifier coupled to receive a differential input signal and providing a differential current mode amplifier output signal;
- a pair of NPN bipolar transistors with collector terminals connected to a power supply node, and gate terminals receiving the differential current mode amplifier output signal;
- a pair of resistors coupled between emitter terminals of the pair of NPN bipolar transistors and corresponding driver output terminals;
- a pair of driver output current sources individually including a first terminal coupled with a ground node, and a second terminal;
- a pair of driver output N-channel field effect transistors individually including a drain terminal coupled to a first terminal of a corresponding one of the pair of resistors, a source terminal coupled to a corresponding one of the driver output current sources, and a gate terminal coupled to a second terminal of the other one of the pair of resistors;
- and
- an RC impedance circuit connected between the second terminals of the driver output current sources.
Dependencies are inferred from the claim text.