DC offset calibration for a radio transceiver mixer
AssigneeBroadcom Corporation
InventorTzi-Hsiung Shu
Life of this patent
Estimating the term…
Abstract
A mixer for a radio transceiver includes a commutating mixer switch having a first differential input port coupled to a DC offset cancellation path. The first differential input port of the mixer switch includes a first terminal coupled to a first end of a first resistor and a second terminal coupled to a first end of a second resistor. Second ends of the first and second resistors are configured to receive a differential input signal. The DC offset cancellation path may provide a resistively coupled DC calibration signal for reducing the magnitude of DC offsets that may be present at the input of the mixer switch. The concept can be used for either image or non-image reject mixers.
Claims31
An image-reject mixer, comprising:
- a first commutating mixer switch having a first input port configured to accept a first resistively coupled differential input signal, a second input port configured to accept a first local oscillator signal and an output port having a positive terminal and a negative terminal;
- and
- a second commutating mixer switch having a first input port configured to accept a second resistively coupled differential input signal that is ninety degrees out of phase with the first differential input signal, a second input port configured to accept a second oscillator signal that is approximately ninety degree out of phase with the first oscillator signal and an output port having a positive terminal coupled to the negative terminal of the output port of the first commutating mixer switch and a negative terminal coupled to the positive terminal of the output port of the first commutating mixer to provide a combined differential output signal.
An image-reject mixer, comprising:
- a first commutating mixer switch having a first differential input port, a second differential input port for accepting a first local oscillator signal and a differential output port;
- a first resistor having a first end coupled to one of the terminals of the first differential input port of the first commutating mixer switch and a second end;
- a second resistor having substantially the same resistance value as the first resistor, the second resistor having a first terminal coupled to the other terminal of the first differential input port and a second end;
- a second commutating mixer switch having a first differential input port, a second differential input port for accepting a second local oscillator signal that is ninety degrees out of phase with the first oscillator signal and a differential output port;
- a third resistor having substantially the same resistance value as the first resistor, the third resistor having a first end coupled to one of the terminals of the first differential input port of the second commutating mixer switch and a second end;
- and
- a fourth resistor having substantially the same resistance value as the first resistor, the fourth resistor having a first end coupled to the other terminal of the first differential input port of the second commutating mixer switch and a second end,
- wherein the second ends of the first and second resistors are configured to receive a first differential input signal, the second ends of the third and fourth resistors are configured to receive a second differential input signal that is ninety degrees out of phase with the first differential input signal, and the differential output port of the first commutating mixer switch is coupled to the differential output port of the second commutating mixer switch.
A mixer for a radio transceiver, comprising:
- a commutating mixer switch having a first input port for accepting a DC compensated signal, the first input port coupled to a DC offset cancellation path, a second input port for accepting a local oscillator signal, and an output port.
A mixer for a radio transceiver, comprising:
- a commutating mixer switch having a first differential input port coupled to a DC offset cancellation path, said first differential input port including a first terminal coupled to a first end of a first resistor and a second terminal coupled to a first end of a second resistor,
- wherein second ends of the first and second resistors are configured to receive a differential input signal.
Dependencies are inferred from the claim text.