Power detectors with temperature compensation and having improved accuracy over temperature are disclosed. In an aspect of the disclosure, variations of a power detector gain over temperature is reduced by varying both the gate and drain voltages of MOS transistors within a power detector. In an exemplary design, an apparatus includes at least one MOS transistor, which receives an input signal, detects the power of the input signal based on a power detection gain, and provides an output signal indicative of the power of the input signal. The at least one MOS transistor is applied a variable gate bias voltage and a variable drain bias voltage in order to reduce variations of the power detection gain over temperature. At least one additional MOS transistor may receive a second variable gate bias voltage and provide the variable drain bias voltage for the at least one MOS transistor.