The invention discloses a sample-and-hold
amplifier which comprises a primary sample-and-hold circuit and a secondary sample-and-hold circuit. The input positive terminal and the input negative terminal of the primary sample-and-hold circuit receive an external
signal, the output positive terminal and the output negative terminal of the primary sample-and-hold circuit are coupled to the input positive terminal and the input negative terminal of the secondary sample-and-hold circuit, the primary sample-and-hold circuit is provided with a primary
operational amplifier with the amplification being less than a multiple, and the secondary sample-and-hold circuit is provided with a secondary
operational amplifier which realizes the amplification more than the multiple; after the external
signal is sampled, held and amplified, by the primary sample-and-hold circuit and the secondary sample-and-hold circuit, the external
signal is output from the output positive terminal and the output negative terminal of the secondary sample-and-hold circuit. Meanwhile, the invention discloses a sample-and-hold method. The sample-and-hold
amplifier, as a basic
signal processing module, is used for front end
processing of the external input signal; and the sample-and-hold
amplifier ensures the speed and the precision of the signal conversion with the simple structure on the premise of realizing high reliability.