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US 7,454,184 B2Granted
DC offset cancellation in a wireless receiver
AssigneeSkyworks Solutions, Inc.
InventorAly M. Ismail
Life of this patent
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Abstract
A DC-offset cancellation system for a wireless receiver is disclosed. The DC-offset cancellation system comprises an amplifier and an impedance inverter configured to transform inductance applied to a received signal to a capacitance.
Claims14
A method for filtering a received signal in a wireless receiver, comprising:
- providing a received signal to a multiple-stage baseband filter chain located between a downconverter and a demodulator, the multiple-stage baseband filter chain comprising an input, variable gain amplifiers and an output;
- inverting the impedance of the received baseband signal in a first stage of a multiple-stage baseband filter chain using an inductance applied at an output of a first stage variable gain amplifier, the baseband filter chain arranged such that a feedback path is located between an output of a first transconductance amplifier and an input of the first transconductance amplifier, the feedback path including a second transconductance amplifier;
- and
- applying a bi-quad filter.
1 more element
A low-noise baseband filter for a wireless receiver, comprising:
- a multiple-stage filter chain, a first stage of the multiple-stage filter chain comprising:
- an amplifier;
- an impedance inverter applied at the output of the amplifier and configured to transform inductance applied to a received baseband signal to a capacitance, the impedance inverter arranged such that a feedback path is located between an output of a first transconductance amplifier and an input of the first transconductance amplifier, the feedback path including a second transconductance amplifier;
- and
- a bi-quad filter coupled to the output of the impedance inverter.
2 more elements
A portable transceiver, comprising:
- a modulator configured to receive and modulate a data signal;
- an upconverter configured to receive the modulated data signal and provide a radio frequency (RF) signal;
- a transmitter configured to transmit the RF signal;
- and
- a direct conversion receiver having a baseband filter chain including an amplifier, a bi-quad filter and an impedance inverter configured to transform inductance applied to a received signal to a capacitance, the impedance inverter having a feedback path located between an output of a first transconductance amplifier and an input of the first transconductance amplifier, the feedback path including a second transconductance amplifier.
2 more elements
A system for removing direct current (DC) offset from a received signal, comprising:
- a variable gain amplifier configured to amplify a downconverted representation of a received radio frequency (RF) signal to generate an amplified baseband signal;
- and
- a gyrator-generated inductance applied at the output of the variable gain amplifier in a first stage of a multiple-stage baseband filter chain, the gyrator-generated inductance configured to transform inductance present at the output of the variable gain amplifier to a capacitance, the gyrator-generated inductance and the variable gain amplifier arranged such that the amplified baseband signal is not applied at an input of the variable gain amplifier, the gyrator-generated inductance implemented via a first transconductance amplifier having differential inputs and a second transconductance amplifier having a single input.
Dependencies are inferred from the claim text.