Noise Analysis of Switched Capacitor Networks in Direct Sampling Mixers

In order to improve the noise figure (NF) of the direct sampling mixer (DSM), thermal noise corresponding to on-resistance of the MOS switch, one of the noise sources in the DSM, is analyzed, and the noise transfer function is derived. As a result, at the output terminal of the DSM, its influence on the desired signal is sufficiently small as compared with the influence which tranceconductance amplifier (TA) in the first stage of the DSM causes. In the DSM, internal noise from switched capacitor filter (SCF) section can be neglected.