Patent ID: 8035422

Claim:
A sample and hold device comprising: 1. a first transconductance amplifier for receiving voltage variations and providing corresponding current variations to be sampled, and a first associated sampling capacitor and a first switching system, the first transconductance amplifier comprising: a. a first transistor of a first type having a first drain for providing current variations to be sampled, the current variations having a useful spectrum centered on a frequency Fo; b. a second transistor of a type opposite to the first type, the second transistor having: i. a source connected to the first drain; ii. a gate biased at a constant potential; iii. a second drain, connected to the switching system, second drain providing the current variations to the sampling capacitor; and c. a filter with a frequency response centered on the central frequency Fo of the current variations, wherein the filter: i. has a very high impedance around this central frequency and a low impedance outside the useful spectrum; and ii. is connected to the source of the second transistor enabling the filter to divert the current variations, which are in a frequency band situated outside the useful spectrum, away from the second transistor.