Polyphase filter with low-pass response
AssigneeAgere Systems Inc.
InventorsVladimir Prodanov, Peter Kiss, Mihai Banu
Life of this patent
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Abstract
A complex low-pass filter that reduces the influence of component mismatch. The filter includes a first filter section for effecting a first single pole transfer function and a second filter section for effecting a second single pole transfer function, where the first and the second single pole transfer functions collectively define a conjugate pair of poles. In higher order low-pass filters, an optimal cascade order follows a shoestring pattern.
Claims21
A low-pass filter comprising:
- a) a first filter section, the first filter section having
- i) first inputs for accepting signals in quadrature, and
- ii) a first sub-section for effecting a first single pole transfer function on the signals accepted by the first inputs, to generate intermediate output signals;
- and
- b) a second filter section, the second filter section having
- i) second inputs for accepting the intermediate output signals generated by the first sub-section of the first filter section, and
- ii) a second sub-section for effecting a second single pole transfer function on the signals accepted by the second inputs to generate a filtered signals,
- wherein the first single pole transfer function and the second single pole transfer function collectively define a conjugate pair of poles.
A low-pass filter comprising N sections, each of the N sections effecting a single pole transfer function, and each of the N sections having a corresponding section defining a conjugate pair of poles,
- wherein each of the poles has a Q value,
- wherein N is at least three, and
- wherein the N sections are cascaded in an order in which the first section of the cascade order has a pole with a lowest Q value and in which the last section of the cascade order has a pole with a lowest Q value.
A method for low-pass filtering a signal, the method comprising:
- a) mixing the signal with an in-phase signal to generate an I signal;
- b) mixing the signal with a quadrature signal to generate a Q signal;
- c) applying the I signal and the Q signal to a first filter section for effecting a first single pole transfer function on the I and Q signals, to generate intermediate output signals;
- and
- d) applying the intermediate output signals to a second filter section for effecting a second single pole transfer function on the intermediate signals to generate a filtered signals,
- wherein the first single pole of the first filter section and the second single pole of the second filter section collectively define a conjugate pair.
A method for low-pass filtering a signal, the method comprising:
- a) mixing the signal with an in-phase signal to generate an I signal;
- b) mixing the signal with a quadrature signal to generate a Q signal;
- c) applying the I signal and the Q signal to a low-pass filter comprising N sections, each of the N sections effecting a single pole transfer function, and each of the N sections having a corresponding section defining a conjugate pair of poles, wherein each of the poles has a Q value, wherein N is at least three, and wherein the N sections are cascaded in an order in which the first section of the cascade order has a pole with a lowest Q value and in which the last section of the cascade order has a pole with a lowest Q value.
A low pass filter comprising:
- (a) a first filter process section, the first filter process section having a
- i) a first input for accepting a complex signal and
- ii) a first processing sub-section for effecting a first single pole transfer function on the signals accepted by the first input, to generate intermediate output signals;
- and
- (b) a second filter process section, the second filter processing section having
- i) a second input for accepting the intermediate output signals generated by the first filter process section, and
- ii) a second processing sub-section for effecting a second single pole transfer function on the signals accepted by the second inputs to generate a filtered signals,
- wherein the first single pole transfer function and the second single pole transfer function collectively define a conjugate pair of poles.
Dependencies are inferred from the claim text.