Receiving system for correcting DC offset and related method thereof
A DC offset and receiving system technology, applied in the field of communication systems, can solve the problems of long response time, inability to accurately correct the signal DC offset, power consumption of the AC coupling circuit, etc.
Active Publication Date: 2013-07-03
REALTEK SEMICON CORP
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Problems solved by technology
However, because the AC coupling circuit in the prior art requires sufficient response time (or frequency response time), if the AC coupling circuit is to be applied to each amplifying circuit or each filtering circuit, the Filtering out the DC offset in the signal will cause the overall response time of the receiving system to be too long
[0003] However, if you choose to use the current compensation operation to correct the DC offset in the signal, you need to wait for a predetermined time before the calibration procedure to determine the magnitude of the current to be compensated. The circuit consumes more power, and the magnitude of the current to be compensated is also easily affected by changes in the operating temperature of the current compensation circuit itself
In fact, the self mixing, local oscillator leakage (LO leakage) of the mixer in the receiving system, or the randomly changing DC offset due to noise is quite unpredictable
Moreover, the magnitude range of the compensation current is roughly a fixed range, thus making it impossible to accurately correct the DC offset in the signal when performing the current compensation operation
Therefore, even though the current compensation circuit can correct the DC offset caused by the mismatch of the transistor process in the amplifier circuit or filter circuit in the receiving system, it cannot accurately correct the self-mixing and local oscillator of the mixer. DC offset due to leakage or noise
Method used
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[0015] FIG. 1 is a schematic diagram of a receiving system 100 according to an embodiment of the present invention. The receiving system 100 includes a low noise amplifier (low noise amplifier, LNA) 105, a mixer 110, a local oscillator (local oscillator, LO) 115, an AC coupling circuit 120, a post-stage circuit 125 and a DC bias Shift correction circuit 130. The low noise amplifier 105 is used to amplify a radio frequency signal S received from the antenna end (not shown in FIG. 1 ) in to generate another RF signal S in ’, and the mixer 110 processes the radio frequency signal S according to the oscillation frequency output by the local oscillator 115 in 'Execute a direct frequency reduction operation to generate a frequency reduction signal S b . The AC coupling circuit 120 is for the down-frequency signal S b Perform AC coupling operation to generate coupled down frequency signal S b ’, and the subsequent stage circuit 125 receives the coupled down-frequency signal S ...
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The invention discloses a receiving system. The system comprises a wave mixer, an AC coupling circuit, a post circuit and a DC drift correction circuit, wherein the wave mixer is used for carrying out direct frequency reduction operation of a radio-frequency signal to generate a frequency reduction signal; the AC coupling circuit is coupled to the wave mixer, and is used for carrying out an AC coupling operation on the frequency reduction signal to generate a coupling frequency reduction signal; the post circuit is coupled to the AC coupling circuit, and is used for receiving the coupling frequency reduction signal to generate an output signal; and the DC drift correction circuit is coupled to the post circuit, and is used for providing at least a certain compensating current to the post circuit to correct DC drift in the output signal through a current compensation operation.
Description
technical field [0001] The present invention relates to a communication system, in particular to a receiving device in the communication system and related methods. Background technique [0002] The DC offset correction mechanism used in a receiving system in the prior art is to use AC coupling (AC coupling) to filter the DC offset in the signal, or to use current compensation operation to correct the DC offset in the signal. However, because the AC coupling circuit in the prior art requires sufficient response time (or frequency response time), if the AC coupling circuit is to be applied to each amplifying circuit or each filtering circuit, the Filtering out the DC offset in the signal will cause the response time required by the receiving system as a whole to be too long. [0003] However, if you choose to use the current compensation operation to correct the DC offset in the signal, you need to wait for a predetermined time before the calibration procedure to determine t...
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IPC IPC(8): H04B1/12H04B15/06
Inventor 邱珮如张家润李朝政
Owner REALTEK SEMICON CORP