Patent ID: 7777479
Filing Date: 2010-08-17
Classification: H03F

Abstract:
1. A current detector with variable output voltage level, comprising: an operational amplifier coupled to an antenna power supply and ground, having a non-inverting input, an inverting input, and an output; an adjusting circuit coupled to the inverting input; a load circuit having one end coupled to the antenna power supply and the other end coupled to the non-inverting input, wherein the other end of the load circuit is also a detecting node; a clamping circuit coupled to the output of the operational amplifier, clamping the output voltage level of the operational amplifier to a predetermined range; and an object circuit selectively coupled to the detecting node; wherein the output voltage level of the clamping circuit is at logic high when the object circuit is not coupled to the detecting node, wherein the output voltage level of the clamping circuit is logic low when the object circuit is coupled to the detecting node, and wherein the object circuit is an active antenna.