Amplitude detection with compensation

An oscillator circuit comprising:

• an oscillator having an output to produce an oscillator signal and a control input to control an amplitude of the oscillator signal;
• an amplitude detector comprising:
• a first current path, the first current path including a first node to provide a voltage indicative of an amplitude of the oscillator signal;
• a first pair of transistors, each transistor of the first pair of transistors is coupled in series with the first current path, the first pair of transistors is coupled in parallel;
• an input to receive the oscillator signal, the input includes a first input terminal coupled to a control terminal of a transistor of the first pair of transistors;
• a compensation circuit comprising:
• a second current path;
• a second pair of transistors, each transistor of the second pair of transistors is coupled in series with the second current path, the second pair of transistors is coupled in parallel, the second pair of transistors includes a first transistor having a control terminal and a second transistor having a control terminal;
• a circuit for setting a voltage differential between the control terminal of the first transistor and the control terminal of the second transistor of the second pair of transistors;
• an output for controlling the amplitude of the oscillator signal coupled to the control input, wherein during a steady state condition, the amplitude of the oscillator signal is proportional to the voltage differential.