The Chopping Technique

• Published in: Capacitively-Coupled Chopper Amplifiers pp. 11 - 27
• Main Authors: Fan, Qinwen, Makinwa, Kofi A. A., Huijsing, Johan H.
• Format: Book Chapter
• Language: English
• Published: Cham Springer International Publishing 01.01.2017
• Series: Analog Circuits and Signal Processing
• Subjects: Charge Injection; Clock Line; Notch Filter; Output Ripple; Simplify Block Diagram
• ISBN: 9783319473901; 3319473905
• ISSN: 1872-082X; 2197-1854
• DOI: 10.1007/978-3-319-47391-8_2

As briefly explained in Chap. 10.1007/978-3-319-47391-8_1, the chopping technique has been applied to convert DC input signals into AC signals that can then be capacitively coupled to the input stage of a capacitively coupled amplifier. Since chopping up-modulates offset and 1/f noise away from DC, high precision, i.e., microvolt offset and low 1/f noise, can be achieved. These characteristics make such amplifiers ideally suited for the amplification of small low-frequency signals. In this chapter, the basic working principle of chopping and its application in precision amplifiers will be discussed. It will be shown that chopping usually results in AC ripple at the chopping frequency, which must then be suppressed. Thus, the techniques to reduce this ripple will also be described. After this, the non-idealities of chopping will be discussed, followed by a summary of its pros and cons. Finally, conclusions will be drawn at the end of the chapter.