Multi-stage amplifier with cascode stage and DC bias regulator

An amplifier, comprising;

• a first amplifier stage comprising:
• a pair of transistors arranged in a cascode amplifier arrangement;
• and
• an isolation circuit;
• a second amplifier stage coupled to an output of the first amplifier stage;
• a voltage source coupled to the first amplifier stage and the second amplifier stage, the isolation circuit being coupled between the a pair of transistors arranged in a cascode amplifier arrangement, the voltage source producing a current serially through the isolation circuit and the pair of transistor in the cascode amplifier arrangement;
• a DC bias regulator comprising:
• a DC bias circuit for producing:
• a voltage related to a reference current produced by the DC bias circuit, such voltage being coupled to a control electrode of a first one of the pair of transistors;
• and
• a combiner having a pair of inputs coupled to:
• the voltage produced by the DC bias circuit and a voltage produced by the isolation circuit, respectively, to produce a DC bias voltage at a control electrode of a second one of the pair of transistors related to a combination of the voltage produced by the DC bias circuit and the voltage produced by the combiner.