Patent ID: 8711982
Filing Date: 2014-04-29
Classification: H03D

Abstract:
1. An envelope detector comprising: an input having a carrier wave that is Amplitude-Modulated (AM) or Amplitude-Shift-Keying (ASK) coded; a clock generator that generates a first sampling clock, a first hold clock, and a first reset clock in a first sequence wherein the first sampling clock is active before the first hold clock is active, and the first hold clock is active before the first reset clock is active, wherein the first sequence has a duration of two or more cycles of the carrier wave of the input, and wherein the first sequence is repeated every two or more cycles of the carrier wave; a first sample switch clocked by the first sampling clock to conduct during a first cycle of the carrier wave; a first rectifier connected to the first sample switch to permit current flow in a first direction and to block current flow in a second direction that is opposite from the first direction; wherein the first sample switch and the first rectifier are connected in series between the input and a first internal node; a first sampling capacitor on the first internal node for storing a first sampled charge that is a function of a peak voltage of the input during the first cycle; a first reset switch on the first internal node for removing the first sampled charge on the first sampling capacitor in response to the first reset clock; and a first hold switch, coupled between the first internal node and a first output node, and clocked by the first hold clock to conduct after the first cycle is completed; wherein the first output node has a first modulated signal that is a function of peaks of the input during the first cycles.