Design and analysis of integrated operational amplifier XD1531 with low noise at low frequencies

Abstract

Principles of design are described for the low frequency integrated operational amplifler XD1531 with low noise. The procedures of design of both the circuit structure and the transistor shape are considered. The first stage of the circuit is designed with the methods of low noise at low frequencies. The measures which decrease noises, especially, the 1/f noise originating from the semiconductor surface state and defects, are used for the transistor structure design. With analysis and comparison to products here and abroad in characteristics, it is shown that XD1531 has a lower noise index at low frequencies than others, and the effectiveness of design methods for bringing low noises have been demonstrated.