Patent ID: 8134410

Claim:
An apparatus having a controllable gain, the apparatus comprising: a first gain stage, wherein the first gain stage is configured to provide a first adjustable positive gain, wherein the first gain stage has a first step size for gain adjustment, wherein the first adjustable positive gain is adjustable at least to a first gain or a second gain, wherein the second gain is larger than the first gain; a second gain stage, wherein the second gain stage is configured to provide a second adjustable positive gain, wherein the second gain stage has a second step size that is less than half the size of the first step size for gain adjustment; an attenuator stage, wherein the attenuator stage is configured to provide adjustable loss, wherein the attenuator stage has a third step size smaller than the second step size for attenuation adjustment, wherein the first gain stage, the second gain stage, and the attenuator stage are cascaded in a forward signal path; and a control circuit configured to control gain of at least one of the first gain stage or the second gain stage for adjustment of at least a part of the total gain, wherein for at least one incremental adjustment of the total gain, the control circuit is configured to adjust the gains of the first gain stage and the second gain stage in opposite directions from each other and to adjust the attenuation of the attenuator stage to reduce differential non-linearity.