Transmission circuit and operation method having output power compensation mechanism

A transmission circuit operation method having output power compensation mechanism, comprising:

• receiving and processing a digital input signal by a base-band and processing circuit to perform conversion and amplification according to at least one a plurality of gain parameters to generate an analog output signal;
• performing frequency up-conversion on the analog output signal by a frequency up-converting circuit to generate a RF signal;
• amplifying the RF signal by a RF amplification circuit to generate an output RF signal to an antenna;
• monitoring and generating an instant temperature value of the RF amplification circuit by a temperature monitoring circuit;
• and
• increasing a digital gain parameter comprised by the gain parameters with a first degree of adjustment when a first time that the transmission circuit performs signal transmission exceeds a first time threshold and when the instant temperature value is larger than a pre-stored reference temperature value to makes a power of the RF amplification circuit decrease by a digital gain compensation circuit comprised by a calibration circuit, and decreasing an analog gain parameter comprised by the gain parameters with a second degree of adjustment when a second time that the transmission circuit does not operate exceeds a second time threshold and when the instant temperature value is smaller than the reference temperature value to makes the power of the RF amplification circuit increase by an analog gain compensation circuit comprised by the calibration circuit, wherein the first degree is less than the second degree.