| 摘要 |
An amplifier (AMP) is provided with a pair of choppers (CHPi,CHPo) in order to reduce the DC-offset and the noise produced by the amplifier (AMP). To obtain an optimal noise reduction the pair of choppers (CHPi,CHPo) operate on a high frequency. As a result the DC-offset cancellation is not optimal because a so-called charge injection of the switches in the pair of choppers (CHPi,CHPo) produces a DC-offset. To overcome this problem the amplifier (AMP) is further provided with further offset cancellation means which are for example formed by a further pair of choppers (CHPfi,CHPfo). This further pair of choppers (CHPfi,CHPfo) operates on a relatively low frequency. The combination of the pair of choppers (CHPi,CHPo) and the further pair of choppers (CHPfi,CHPfo) guarantees an optimal DC-offset cancellation as well as an optimal noise cancellation.
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