Fully integrated long time constant integrator circuit
AssigneeNortel Networks Limited
InventorsPasqualino Michelle Visocchi, Edward J W Whittaker, Robin M Flett
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Abstract
The present invention provides a long time constant integrator circuit as part of an integrated circuit. The integrator circuit is fully integrated on chip with no external capacitive or resistive components for enhancing the circuit's time constant. It achieves a −3 dB cut-off frequency of 1.6 Hz. The circuit is realisable on a very small area of silicon being formed by a bipolar process using npn transistors, resistive and capacitive elements. The integrator circuit comprises a transconductance stage as an input to an operational amplifier. The circuit design is fully differential and employs realisable resistors and capacitors.
Claims32
An integrated circuit (IC) integrator comprising:
- an attenuation stage;
- an amplifier stage;
- a resistive element R coupling the output of the attenuation stage to the input of the amplifier stage;
- and
- a capacitive element C in a feedback loop coupling the output to the input of the amplifier stage, the capacitive and resistive elements defining between them a fundamental time constant CR, whereby the attenuation stage is arranged to attenuate an input signal thereby enhancing the effective time constant of the circuit, and
- a feedback loop coupling the output of the amplifier stage to the input of the attenuation stage, said feedback loop including an additional resistive element.
An optical receiver including an integrated circuit (IC) integrator comprising:
- an attenuation stage;
- an amplifier stage;
- a resistive element R coupling the output of the attenuation stage to the input of the amplifier stage;
- a capacitive element C in a feedback loop coupling the output to the input of the amplifier stage, the capacitive and resistive elements defining between them a fundamental time constant CR, whereby the attenuation stage is arranged to attenuate an input signal thereby enhancing the effective time constant of the circuit, and
- a feedback loop coupling the output of the amplifier stage to the input of the attenuation stage, said feedback loop including an additional resistive element.
An integrated circuit (IC) integrator comprising:
- an attenuation stage;
- an amplifier stage;
- a resistive element R coupling the output of the attenuation stage to the input of the amplifier stage;
- a capacitive element C in a feedback loop coupling the output to the input of the amplifier stage, the capacitive and resistive elements defining between them a fundamental time constant CR, whereby the attenuation stage is arranged to attenuate an input signal thereby enhancing the effective time constant of the circuit,
- wherein the attenuation stage comprises an input transconductance stage a resistive driver network
- wherein the resistive divider network comprising a first resistive element coupling the output of the input transconductance stage to the resistive element R and a second resistive element coupling the resistive element R and ground, wherein the first resistive element has a value considerably greater than that of the second resistive element.
An optical receiver including an integrated circuit (IC) integrator comprising:
- an attenuation stage;
- an amplifier stage;
- a resistive element R coupling the output of the attenuation stage to the input of the amplifier stage;
- a capacitive element C in a feedback loop coupling the output to the input of the amplifier stage, the capacitive and resistive elements defining between them a fundamental time constant CR, whereby the attenuation stage is arranged to attenuate an input signal thereby enhancing the effective time constant of the circuit.
An integrated circuit (IC) integrator comprising:
- an attenuation stage;
- an amplifier stage;
- a resistive element R coupling the output of the attenuation stage to the input of the amplifier stage;
- a capacitive element C in a feedback loop coupling the output to the input of the amplifier stage, the capacitive and resistive elements defining between them a fundamental time constant CR, whereby the attenuation stage is arranged to attenuate an input signal thereby enhancing the effective time constant of the circuit,
- and wherein the integrated circuit integrator includes an input resistive element coupling an input side of the junction of the feedback loop to the input of the attenuation stage.
An optical receiver including an integrated circuit (IC) integrator comprising:
- an attenuation stage;
- an amplifier stage;
- a resistive element R coupling the output of the attenuation stage to the input of the amplifier stage;
- a capacitive element C in a feedback loop coupling the output to the input of the amplifier stage, the capacitive and resistive elements defining between them a fundamental time constant CR, whereby the attenuation stage is arranged to attenuate an input signal thereby enhancing the effective time constant of the circuit,
- and wherein the integrated circuit integrator includes an input resistive element coupling an input side of the junction of the feedback loop to the input of the attenuation stage.
Dependencies are inferred from the claim text.