Chopper amplifiers themselves are not necessarily a new idea. The first chopper amplifier patent was filed in 1949. These earliest implementations of chopper amplifiers used mechanical vibrators to “chop” the DC input signal to create an AC signal. The AC signal was then amplified (tube/valve circuitry) and synchronously rectified to recover the DC component. This technique did provide very low offset voltage and offset voltage drift, but it really had very poor bandwidth. It also added considerable high frequency chopping noise that required additional filtering and further limited the useful bandwidth of the amplifier.