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US 8,149,052 B2Granted
Method and apparatus to linearize transconductors by predistortion
AssigneeACP Advanced Circuit Pursuit AG
InventorsQiuting Huang, Dimitrios Filippos Papadopoulos, Jurgen Rogin
Life of this patent
Estimating the term…
Abstract
A transconductor for providing an output current that is linear in the input voltage (Vin) comprises a main output transconductor (Ms, Mc) and a model transconductor (Msr1, Msr2, Mcr1, Mcr2) that are controlled by the same signal (Vc, Vc′). The latter transconductor (Msr1, Msr2, Mcr1, Mcr2) is comprised in a predistortion circuit (A), which measures the output of the model transconductor and the overall voltage input (Vin) to provide a control signal (Vc, Vc′) for the transconductors that compensates for their non-linearity.
Claims31
A transconductor circuit comprising:
- an output transconductor having a control input and an output responsive to the signal at the control input, and
- a predistortion circuit comprising:
- a control input,
- a model transconductor, having an input voltage to output current characteristic where the output current is related to that of the output transconductor by a constant factor, which factor includes a factor of one, and having a control input and an output responsive to the signal at its control input,
- a feedback network
- that is connected to receive the signal at the control input to the predistortion circuit,
- that has a feedback input connected to receive a feedback signal indicative of the signal output from the output of the model transconductor, and has a control output connected to supply a transconductor control signal to the control input of the model transconductor and to the control input of the output transconductor, and
- that is responsive to the signal from the control input to the predistortion circuit and to the feedback signal indicative of the signal output from the output of the model transconductor, in providing the transconductor control signal, to control the output of the model transconductor to be linear with respect to the signal at the control input of the predistortion circuit, and
- a conditioner circuit having an input connected to receive the transconductor control signal and an output connected to provide a conditioned version of that signal to the output transconductor, wherein the model transconductor is connected to receive the transconductor control signal before it is passed through the conditioner circuit.
6 more elements
A transconductor circuit comprising:
- an output transconductor having a control input and an output responsive to the signal at the control input, and
- a predistortion circuit comprising:
- a control input,
- a model transconductor, having an input voltage to output current characteristic where the output current is related to that of the output transconductor by a constant factor, which factor includes a factor of one, and having a control input and an output responsive to the signal at its control input,
- a feedback network
- that is connected to receive the signal at the control input to the predistortion circuit,
- that has a feedback input connected to receive a feedback signal indicative of the signal output from the output of the model transconductor, and has a control output connected to supply a transconductor control signal to the control input of the model transconductor and to the control input of the output transconductor, and
- that is responsive to the signal from the control input to the predistortion circuit and to the feedback signal indicative of the signal output from the output of the model transconductor, in providing the transconductor control signal, to control the output of the model transconductor to be linear with respect to the signal at the control input of the predistortion circuit, and
- a conditioner circuit having an input connected to receive the transconductor control signal and an output connected to provide a conditioned version of that signal to the output transconductor, wherein the conditioner circuit comprises a low pass filter.
6 more elements
A transconductor circuit comprising:
- an output transconductor having a control input and an output responsive to the signal at the control input, and
- a predistortion circuit comprising:
- a control input,
- a model transconductor, having an input voltage to output current characteristic where the output current is related to that of the output transconductor by a constant factor, which factor includes a factor of one, and having a control input and an output responsive to the signal at its control input,
- a feedback network
- that is connected to receive the signal at the control input to the predistortion circuit,
- that has a feedback input connected to receive a feedback signal indicative of the signal output from the output of the model transconductor, and has a control output connected to supply a transconductor control signal to the control input of the model transconductor and to the control input of the output transconductor, and
- that is responsive to the signal from the control input to the predistortion circuit and to the feedback signal indicative of the signal output from the output of the model transconductor, in providing the transconductor control signal, to control the output of the model transconductor to be linear with respect to the signal at the control input of the predistortion circuit, and
- a servo circuit connected to sense an operating condition of the output transconductor and to apply that operating condition to the model transconductor.
6 more elements
A method of controlling an output transconductor comprising:
- providing an output transconductor and a model transconductor having an input voltage to output current characteristic where the output current is related to that of the output transconductor by a constant factor, which factor includes a factor of one, receiving an input control signal, sensing the output of the model transconductor, providing, in response to the input control signal and to a signal indicative of the output of the model transconductor, a transconductor control signal to control the output of the model transconductor to be linear with respect to the input control signal, applying the transconductor control signal to the output transconductor to control the output thereof, and low pass filtering the transconductor control signal before it is applied to the output transconductor.
A method of controlling an output transconductor comprising:
- providing an output transconductor and a model transconductor having an input voltage to output current characteristic where the output current is related to that of the output transconductor by a constant factor, which factor includes a factor of one, receiving an input control signal, sensing the output of the model transconductor, providing, in response to the input control signal and to a signal indicative of the output of the model transconductor, a transconductor control signal to control the output of the model transconductor to be linear with respect to the input control signal, applying the transconductor control signal to the output transconductor to control the output thereof, sensing an operating condition of the output transconductor and applying that operating condition to the model transconductor.
Dependencies are inferred from the claim text.