Envelope detector with enhanced linear range

A linearizer circuit comprising:

• a differential amplifier comprising first and second transistors configured to respectively receive differential positive and negative outputs from an envelope detector (ED);
• a first impedance coupled between sources of the first and second transistors;
• the differential amplifier further comprising third and fourth transistors having drains connected, respectively, to drains of the first and second transistors and being driven by the drains of the first and second transistors through, respectively, second and third impedances that interconnect at gates of the third and fourth transistors;
• and
• further comprising a linearizer output at the drain of the fourth transistor and configured to drive biasing transistors of the ED, the biasing transistors configured to set bias currents of envelope-detecting transistors of the ED.

An envelope detector comprising:

• a voltage-mode envelope detector (ED) core including a first and a second pair of parallel detection transistors for detecting a voltage envelope of a radio frequency (RF) signal input, where the detection transistors are configured to be biased in a subthreshold region of operation, the first pair of transistors driven by differential inputs from the RF signal input to generate a positive ED output, and the second pair of transistors configured to generate a negative ED output;
• the ED core further including a current-biasing transistor for the first pair and for the second pair, where a bias voltage of the current-biasing transistors determines a bias current for each pair of detection transistors;
• and
• a linearizer circuit configured with a differential amplifier coupled to the positive and negative ED outputs, the linearizer circuit configured to generate the bias voltage as proportional to a difference between the positive and negative ED outputs, to enhance a linear range of the ED while maintaining the detection transistors in subthreshold regions despite a widened voltage amplitude range of the RF signal input.