This paper presents the two main circuit techniques, namely autozeroing (AZ) and chopper stabilization (CS), that are used to reduce the 1/f noise and offset in amplifiers typically used in sensor electronics interfaces. After recalling their main properties, it looks into recent trends in circuit noise reduction techniques. First, the correlated multiple sampling (CMS) technique is presented as a generalization of AZ and correlated double sampling (CDS). Introduced in CMOS image sensors (CIS), it combines noise averaging and canceling and allows to further reduce the 1/f noise, but, like AZ, it is also ultimately limited by the aliasing of the broadband white noise. Another technique combining noise canceling and CS in a transimpedance amplifier (TIA) for bio-sensors is presented. It allows to maintain a low input impedance required by the TIA, while reducing the noise of the main transimpedance stage. CS is then used to cancel the noise of the following stages.