Variable-gain constant-bandwidth transimpedance amplifier
AssigneeMarvell International Ltd.
InventorFarbod Aram
Life of this patent
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Abstract
An amplifier circuit includes a first operational transconductance amplifier (OTA) having an input and an output. A second OTA has an input that communicates with the output of the first OTA and an output. A first feedback path communicates with the input and the output of the first OTA and includes a first resistance. A second feedback path communicates with the input and the output of the second OTA and includes a second resistance. A third feedback path communicates with the input of the first OTA and the output of the second OTA. The first and second resistances are variable resistances that have resistance values that decrease as frequency increases.
Claims23
An amplifier circuit comprising:
- a first operational transconductance amplifier (OTA) having an input and said output;
- a second OTA having an input that communicates with an output of said first OTA and an output;
- a first feedback path that communicates with said input and said output of said first OTA and that includes a first resistance;
- a second feedback path that communicates with said input and said output of said second OTA and that includes a second resistance;
- and
- a third feedback path that communicates with said input of said first OTA and said output of said second OTA,
- wherein said first and second resistances are variable resistances that have resistance values that decrease as frequency increases.
An amplifier circuit comprising:
- a first operational transconductance amplifier (OTA) having an input and an output;
- a second OTA having an input that communicates with said output of said first OTA and an output;
- a first feedback path that communicates with said input and said output of said first OTA and that includes a first resistance;
- a second feedback path that communicates with said input and said output of said second OTA and that includes a second resistance;
- and
- a third feedback path that communicates with said input of said first OTA and said output of said second OTA,
- wherein said first feedback path includes a first capacitance in parallel with said first resistance and wherein said second feedback path includes a second capacitance in parallel with said second resistance.
An amplifier circuit comprising:
- a first operational transconductance amplifier (OTA) having an input and an output;
- a second OTA having an input that communicates with said output of said first OTA and an output;
- a first feedback path that communicates with said input and said output of said first OTA and that includes a first resistor;
- a second feedback path that communicates with said input and said output of said second OTA and that includes a second resistance;
- a third feedback path that communicates with said input of said first OTA and said output of said second OTA;
- and
- a third OTA having an input that communicates with said output of said first OTA and an output that communicates with said input of said second OTA.
A method for operating an amplifier circuit, comprising:
- providing first and second operational transconductance amplifiers (OTAs), each having inputs and outputs;
- feeding back said output of said first OTA to said input of said first OTA via a first resistance;
- feeding back said output of said second OTA to said input of said second OTA via a second resistance;
- feeding back said output of said second OTA to said input of said first OTA;
- and
- lowering a second resistance value of said second resistance at high frequencies relative to said second resistance value low frequencies.
A method for operating an amplifier circuit, comprising:
- providing first and second operational transconductance amplifiers (OTAs), each having inputs and outputs;
- feeding back said output of said first OTA to said input of said first OTA via a first resistance;
- feeding back said output of said second OTA to said input of said second OTA via a second resistance;
- feeding back said output of said second OTA to said input of said first OTA;
- and
- implementing said first resistance using a third resistance in parallel with a first capacitance and a fourth resistance in series with said third resistance.
A method for operating an amplifier circuit, comprising:
- providing first and second operational transconductance amplifiers (OTAs), each having inputs and outputs;
- feeding back said output of said first OTA to said input of said first OTA via a first resistance;
- feeding back said output of said second OTA to said input of said second OTA via a second resistance;
- feeding back said output of said second OTA to said input of said first OTA;
- and
- implementing said second resistance using a fifth resistance in parallel with a second capacitance and a sixth resistance in series with said fifth resistance.
Dependencies are inferred from the claim text.