Patent ID: 9360504
Filing Date: 2016-06-07
CPC Classification: G01R,G06K,H03D,H04B,H04L

Claim Text:
1. An envelope detector circuit for detecting an envelope waveform in an input signal applied to an input of the envelope detector circuit, the envelope detector circuit comprising: an input capacitor connected between the input and a first circuit node of a first circuit branch, the first circuit branch being connected between a first power source and a second power source, wherein the first circuit branch comprises an output capacitor being connected between the second circuit node and the second power source, wherein the first rectifying element comprises a first transistor, wherein the envelope detector circuit further comprises a biasing voltage generating circuit for generating a biasing voltage, wherein the biasing voltage is provided to a control gate of the first transistor, the biasing voltage generating circuit being arranged so as to permit a determined forward biasing current to flow through the first and second rectifying elements when no input signal is applied to the input, wherein the first transistor and the biasing voltage being selected such that, at least when no input signal is applied to the input, the first transistor operates in weak inversion mode, and wherein the biasing voltage generating circuit comprises, in series, a first current source and a second circuit branch connected between the first power source and the second power source, the second circuit branch comprising, in series, a second transistor, matched to the first transistor, and a matching element matched to the second rectifying element.