Folded-cascode amplifier with adjustable continuous time equalizer
First Claim
1. A folded cascode amplifier circuit comprising:
- a first order high-pass filter coupled to a first bias voltage, a first input signal and a second input signal, the first input signal and the second input signal defining a differential input signal and the first order high-pass filter arranged to establish a first bias output and a second bias output;
a full-spectrum content amplifier coupled between the first input signal, the second input signal and a current source, the full-spectrum content amplifier arranged to amplify the differential input signal and to output an amplified differential input signal;
a high-frequency content amplifier comprising a first transistor having a control terminal coupled to the first bias output of the first order high-pass filter, a first terminal coupled to ground and a second terminal coupled to the output of the full-spectrum content amplifier and a second transistor having a control terminal coupled to the second bias output of the first order high-pass filter, a first terminal coupled to ground and a second terminal coupled to the output of the first order high-pass filter, the high-frequency content amplifier arranged to amplify the high-frequency content of the differential input signal and to output an amplified high-frequency component of the differential input signal;
a summing circuit comprising a first transistor having a first terminal coupled to the second terminal of the first transistor of the high-frequency content amplifier and a second transistor having a first terminal coupled to the second terminal of the second transistor of the high-frequency content amplifier and a control terminal coupled to a control terminal of the first transistor of the summing circuit, the summing circuit to receive the amplified differential input signal from the full-spectrum content amplifier and to receive the amplified high-frequency component of the differential input signal from the high-frequency content amplifier, the summing circuit to output a summed output current to achieve equalization of the differential input signal; and
an output conversion circuit comprising a first input coupled to a second terminal of the first transistor of the summing circuit and a second input coupled to a second terminal of the second transistor of the summing circuit, the output conversion circuit to convert the summed output current from the summing circuit to an output voltage.
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Accused Products
Abstract
A system and method are provided for a folded cascode amplifier circuit that includes a first order high-pass filter coupled to a first bias voltage, a first input signal and a second input signal, the first input signal and the second input signal defining a differential input signal and the first order high-pass filter arranged to establish a first bias output and a second bias output. To amplify the full-spectrum content of the input signal, the amplifier circuit includes a full-spectrum content amplifier coupled between the first input signal, the second input signal and a current source. To amplify the high-frequency content of the input signal to achieve equalization, the amplifier circuit includes a high-frequency content amplifier coupled to the first bias output and the second bias output, the high-frequency content amplifier arranged to amplify the high-frequency content of the differential input signal to achieve equalization.
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Citations
18 Claims
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1. A folded cascode amplifier circuit comprising:
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a first order high-pass filter coupled to a first bias voltage, a first input signal and a second input signal, the first input signal and the second input signal defining a differential input signal and the first order high-pass filter arranged to establish a first bias output and a second bias output; a full-spectrum content amplifier coupled between the first input signal, the second input signal and a current source, the full-spectrum content amplifier arranged to amplify the differential input signal and to output an amplified differential input signal; a high-frequency content amplifier comprising a first transistor having a control terminal coupled to the first bias output of the first order high-pass filter, a first terminal coupled to ground and a second terminal coupled to the output of the full-spectrum content amplifier and a second transistor having a control terminal coupled to the second bias output of the first order high-pass filter, a first terminal coupled to ground and a second terminal coupled to the output of the first order high-pass filter, the high-frequency content amplifier arranged to amplify the high-frequency content of the differential input signal and to output an amplified high-frequency component of the differential input signal; a summing circuit comprising a first transistor having a first terminal coupled to the second terminal of the first transistor of the high-frequency content amplifier and a second transistor having a first terminal coupled to the second terminal of the second transistor of the high-frequency content amplifier and a control terminal coupled to a control terminal of the first transistor of the summing circuit, the summing circuit to receive the amplified differential input signal from the full-spectrum content amplifier and to receive the amplified high-frequency component of the differential input signal from the high-frequency content amplifier, the summing circuit to output a summed output current to achieve equalization of the differential input signal; and an output conversion circuit comprising a first input coupled to a second terminal of the first transistor of the summing circuit and a second input coupled to a second terminal of the second transistor of the summing circuit, the output conversion circuit to convert the summed output current from the summing circuit to an output voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for achieving equalization in a folded cascode amplifier, the method comprising the steps of:
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receiving a first input signal and a second input signal defining a differential input signal; applying a tail current source to establish a tail bias current; amplifying the differential input signal using a first transistor circuit biased by the tail bias current; extracting the high-frequency component of the differential input signal using a high-pass filter comprising a switched resistor array, a first bias voltage and two parallel capacitors; generating an adjustable −
3 db bandwidth with the switched resistor array and the first bias voltage;amplifying the high-frequency component using a second transistor circuit biased by the first bias voltage; summing the amplified high-frequency component of the input signal and the amplified differential input signal resulting in a summed output current to achieve equalization of the input signal; and converting the summed output current to an output voltage. - View Dependent Claims (10, 11, 12, 13)
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14. A folded cascode amplifier circuit having adjustable continuous time equalization, the circuit comprising:
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a first amplification circuit for receiving a differential input signal and a tail current bias source, the first amplification circuit being arranged to amplify the differential input signal, wherein the gain of the first amplification circuit is in part determined by the tail current bias source; a second amplification circuit for receiving the differential input signal and a first bias voltage, the second amplification circuit being arranged to extract a high-frequency component of the input signal and to amplify the high-frequency component of the input signal, wherein the second amplification circuit further comprises a switched resistor array arranged to receive the differential input signal and the first bias voltage, the gain of the second amplification circuit is in part determined by the first bias voltage; and a summing circuit to sum the amplified differential input signal from the first amplification circuit and the amplified high-frequency component of the second amplification circuit. - View Dependent Claims (15, 16, 17, 18)
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Specification