The effect of the upper sideband on the performance of a parametric amplifier

The equations which represent the effect of the upper sideband in a conventional parametric amplifier are derived in detail. It is then shown that the effect of the upper sideband is to present a positive conductance to the signal circuit and partly to nullify the negative resistance associated with the idler circuit. The noise figure expression is derived and shows that noise is introduced into the amplifier at the upper sideband and is converted to signal circuit, degrading the noise figure of the amplifier.