US Patent 10056874 Power amplifier self-heating compensation circuit

Temperature compensation circuits and methods for adjusting one or more circuit parameters of a power amplifier (PA) to maintain approximately constant Gain versus time during pulsed operation sufficient to substantially offset self-heating of the PA. Some embodiments compensate for PA Gain “droop” due to self-heating using a Sample and Hold (S&H) circuit. The S&H circuit samples and holds an initial temperature of the PA at commencement of a pulse. Thereafter, the S&H circuit generates a continuous measurement that corresponds to the temperature of the PA during the remainder of the pulse. A Gain Control signal is generated that is a function of the difference between the initial temperature and the operating temperature of the PA as the PA self-heats for the duration of the pulse. The Gain Control signal is applied to one or more adjustable or tunable circuits within a PA to offset the Gain droop of the PA.