Analog Pre-Distorter

An amplifier system, comprising an amplifier having an input terminal and an output terminal, and an analog pre-distorter, wherein the analog pre-distorter comprises:

• an input node for receiving an RF signal at an operational frequency ω;
• an output node connected to the input terminal of the amplifier;
• a buffer amplifier having a buffer input and a buffer output that is connected to the output node, wherein the buffer amplifier comprises a source follower or emitter follower;
• a parallel connection of a non-linear dissipative element and a reactive element, wherein one end of the parallel connection is connected to the input node and wherein another end of the parallel connection is connected to the buffer input;
• and
• a biasing unit for DC biasing the non-linear dissipative element;
• wherein the non-linear dissipative element has a non-linear current-voltage relationship, wherein a dynamic resistance Rdyn of the non-linear dissipative element increases with increasing DC bias voltage across the non-linear dissipative element such that for a given DC bias voltage across the non-linear dissipative element, a power gain of the analog pre-distorter expands when power of the RF signal is increased;
• wherein the amplifier displays gain compression and a phase shift between the input terminal and output terminal that decreases or increases with increasing power of the RF signal;
• wherein the analog pre-distorter is configured for at least partially compensating the gain compression and/or decrease or increase in phase shift of the amplifier;
• wherein the operational frequency lies above 1 GHz, and wherein the amplifier is configured for outputting a power that exceeds 0.5W;
• and
• wherein the amplifier and at least part of the analog pre-distorter are integrated on a compound semiconductor die.