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DC offset cancellation circuit for a receiver

A technology of offset voltage and circuit, applied in the direction of electrical components, angle modulation oscillation demodulation, oscillation conversion angle demodulation, etc., can solve problems such as incorrect output

Inactive Publication Date: 2008-11-26
QUALCOMM INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Therefore, when the ADC is saturated with DC offset, the ADC will output incorrect values

Method used

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  • DC offset cancellation circuit for a receiver
  • DC offset cancellation circuit for a receiver
  • DC offset cancellation circuit for a receiver

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Embodiment Construction

[0016] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or design referred to herein as "exemplary" is not necessarily to be construed as preferred or superior to other embodiments or designs.

[0017] The DC offset cancellation circuits described herein may be used in direct conversion receivers, such as zero-IF receivers, and may be used in other types of receivers. The direct conversion receiver downconverts the received RF signal from RF directly to baseband in one stage. Other types of receivers perform downconversion in multiple stages. The different types of receivers may use different circuit blocks and / or have different circuit requirements. For clarity, the DC offset cancellation circuit is described below for a direct conversion receiver.

[0018] FIG. 1 shows a block diagram of an RF receiver 100 including a DC offset cancellation circuit. Within receiver 100, a low noise amplifier (LNA) 80 amplifies...

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Abstract

Techniques for cancelling DC offset are described. A DC offset cancellation circuit in a receiver cancels DC offsets caused by leaked LO (local oscillator) signals from a LO signal generator. The receiver first calibrates itself by using the DC offset cancellation circuit during a transmit mode. During the calibration, the DC offset cancellation circuit stores the DC offset voltage signal caused by the leaked LO signals. During a receiving mode when the receiver is receiving a signal, the receiver subtracts the stored DC offset voltage signal from the received signal to cancel the DC offsets caused by leaked LO signals.

Description

[0001] Related Application Cross Reference [0002] This patent application claims priority to Provisional Application No. 60 / 722,063, filed September 28, 2005, and entitled "DC OFFSET CANCELLATION CIRCUIT," and the Said provisional application is assigned to the assignee of the present application and is expressly incorporated herein by reference. technical field [0003] The present invention relates generally to electronic devices, and more particularly to DC offset cancellation circuits in receivers. Background technique [0004] In digital communication systems, a transmitter processes traffic data to generate data chips and further modulates a local oscillator (LO) signal with the data chips to generate a radio frequency (RF) modulated signal. The transmitter then transmits the RF modulated signal via the communication channel. The communication channel degrades the RF modulated signal by noise and possible interference from other transmitters. [0005] The receive...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03D3/00
CPCH03D3/008H03D3/00H04B1/10
Inventor 孙润华克里斯琴·赫伦斯坦詹姆斯·贾菲
Owner QUALCOMM INC
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