Amplifier with dynamic bias

An amplifier for amplifying an input signal to generate an output signal, the amplifier comprising a first bias transistor having a first bias level, the gain of the amplifier being a function of the first bias level, the amplifier further comprising:

• a first detector for measuring a first envelope of the output signal;
• a first bias adjuster for shifting the voltage level of the output voltage of the first detector, the output of the first bias adjuster adjusting the first bias level;
• a second bias transistor having a second bias level, the gain of the amplifier being a function of the second bias level, the first bias transistor being an NMOS transistor, and the second bias transistor being a PMOS transistor;
• a first NMOS transistor and a first PMOS transistor, the drain of the first NMOS transistor coupled to the drain of the first PMOS transistor, the sources of the first NMOS transistor and the first PMOS transistor coupled to the first and second bias transistors, respectively, the gate of the first NMOS transistor coupled to the gate of the first PMOS transistor, the gates of the first NMOS transistor and the first PMOS transistor coupled to the input signal, and the drains of the first NMOS and PMOS transistors coupled to the output signal;
• and
• a resistor coupling the output signal to the input signal.

A method for amplifying an input signal to generate an output signal, the amplifying comprising coupling an input signal to an amplifier to generate an output signal, the amplifier comprising a first bias transistor having a first bias level, the gain of the amplifier being a function of the first bias level, the method comprising:

• measuring a first envelope of the output signal with a first detector;
• shifting the voltage level of the measured envelope of the output signal with a first bias adjuster, the measuring the first envelope comprising passing the output signal through a first diode, and low-pass filtering the output of the diode, the shifting the voltage level comprising passing the measured envelope through a source follower;
• and
• adjusting the first bias level with said shifted voltage level.

A method for amplifying an input signal to generate an output signal, the amplifying comprising coupling an input signal to an amplifier to generate an output signal, the amplifier comprising a first bias transistor having a first bias level, the gain of the amplifier being a function of the first bias level, the method comprising:

• measuring a first envelope of the output signal with a first detector;
• shifting the voltage level of the measured envelope of the output signal with a first bias adjuster;
• and
• adjusting the first bias level with said shifted voltage level, the first detector comprising a comparator for comparing the output signal to a reference signal, the output of the comparator coupled to a switch, the switch coupling the output signal to an envelope detector, the output of the envelope detector coupled to the first bias adjuster.

An amplifier for amplifying an input signal to generate an output signal, the amplifier comprising a first bias transistor having a first bias level, the gain of the amplifier being a function of the first bias level, the amplifier further comprising:

• means for measuring a first envelope of the output signal;
• and
• means for shifting the voltage level of the output voltage of the means for measuring a first envelope, the output of said means for shifting adjusting the first bias level;
• a second bias transistor having a second bias level, the gain of the amplifier further being a function of the second bias level;
• means for measuring a second envelope of the output signal;
• and
• means for shifting the voltage level of the output voltage of the means for measuring a second envelope, the output of said means for shifting adjusting the second bias level.