Abstract: A demodulation method and apparatus are provided. An RF signal is down converted to generate a first in-phase signal and a first quadrature signal of a first frequency. Limiting amplification is performed on the first in-phase signal and the first quadrature signal to generate a second in-phase signal and a second quadrature signal. The frequency of the second in-phase and quadrature signals are up converted to a third in-phase signal and a quadrature signal of a second frequency. The third in-phase and quadrature signals are up converted to generate an intermediate frequency (IF) signal of a third frequency.

Abstract: A gain control circuit and a variable gain amplifier using the same. In the variable gain amplifier, gain control circuit generates a gain control voltage according to a control voltage, and a gain variable amplification unit is coupled to the gain control circuit and an input voltage to adjust an output signal output to a load according to the gain control voltage. In the gain control circuit, a level shifter with a constant current source generates a first voltage according to a control voltage. A first temperature compensation unit has a first temperature-controlled current source, and generates a second voltage according to a present operating temperature. A voltage conversion unit coupled to the level shifter and the first temperature compensation unit generates a gain control voltage according to the first and second voltages.

Abstract: A voltage supplying apparatus is provided for supplying an output voltage to an electronic circuit. The electronic circuit includes a first voltage-drop device. The voltage supplying apparatus includes a current source for supplying a constant current, a second voltage-drop device, and a regulator. The second voltage-drop device is coupled with the current source and has the same feature in process deviation with the first voltage-drop device. The regulator for stabilizing the output voltage includes a voltage input terminal and a voltage output terminal. The voltage input terminal is coupled with the current source and has a first voltage corresponding to the output voltage. The voltage output terminal provides the output voltage and a corresponding output current. When the output current is deviated due to the process deviation of the first voltage-drop device, the first voltage will be shifted accordingly to offset the output current deviation.

Abstract: A gain control circuit and a variable gain amplifier using the same. In the variable gain amplifier, gain control circuit generates a gain control voltage according to a control voltage, and a gain variable amplification unit is coupled to the gain control circuit and an input voltage to adjust an output signal output to a load according to the gain control voltage. In the gain control circuit, a level shifter with a constant current source generates a first voltage according to a control voltage. A first temperature compensation unit has a first temperature-controlled current source, and generates a second voltage according to a present operating temperature. A voltage conversion unit coupled to the level shifter and the first temperature compensation unit generates a gain control voltage according to the first and second voltages.

Abstract: Mixers are provided. A mixer includes an output port, a local oscillation input port, a local mixing driving stage, a radio frequency (RF) input port, a RF driving stage, and first to fourth calibration units. The local oscillation input port comprises first and second local input terminals for receiving a pair of local oscillation signals (LO+ and LO?). The local mixing driving stage comprises first, second, third, and fourth transistors. The first to fourth calibration units are respectively connected in parallel with the first to fourth transistors to constitute first to fourth current path switches, wherein by controlling the switches, the turn-on period of the first and fourth current path switches driven by the local oscillation signal LO+is virtually equal to those of the second and third current path switches driven by the local oscillation signal LO?.

Abstract: A receiver comprising an in-phase channel circuit, a quadrature channel circuit, and a gain imbalance calibration circuit comprising a first circuit and a second circuit. The first circuit provides testing signals to the in-phase channel circuit and the quadrature channel circuit. Test resultant signals output from the in-phase channel circuit and the quadrature channel circuit are input to the second circuit. The second circuit calibrates the gain of baseband amplifiers of the in-phase channel and the quadrature channel circuit according to the offset between the test resultant signals, thereby enabling the test resultant signal of the in-phase channel circuit to be substantially equal to the test resultant signal of the quadrature channel circuit.

Abstract: A voltage supplying apparatus is provided for supplying an output voltage to an electronic circuit. The electronic circuit includes a first voltage-drop device. The voltage supplying apparatus includes a current source for supplying a constant current, a second voltage-drop device, and a regulator. The second voltage-drop device is coupled with the current source and has the same feature in process deviation with the first voltage-drop device. The regulator for stabilizing the output voltage includes a voltage input terminal and a voltage output terminal. The voltage input terminal is coupled with the current source and has a first voltage corresponding to the output voltage. The voltage output terminal provides the output voltage and a corresponding output current. When the output current is deviated due to the process deviation of the first voltage-drop device, the first voltage will be shifted accordingly to offset the output current deviation.

Abstract: An automatic adjustment system for source current and sink current mismatch. The system includes a startup compensation/setup device to perform initialization current compensation and accordingly implement a control reference table, a determination device to output a control signal according to the control reference table, and a current compensation device to switch corresponding internal switches on and off according to the control signal and complete the desired compensation for source current and sink current mismatch.

Abstract: A component inaccuracy correction system has a current source capable of outputting two currents with a fixed ratio, a voltage dividing circuit formed on the integrated circuit having at least an output end capable of receiving a current of the current source to output a divided voltage, a reference voltage generator capable of receiving another current of the current source to output a reference voltage, a comparison circuit electrically connected to the output end of the voltage dividing circuit for receiving the divided voltage from the voltage dividing circuit and comparing the divided voltage to the reference voltage to create a corresponding comparison signal, and a correction circuit electrically connected to the comparison circuit for correcting component inaccuracies of the integrated circuit according to the comparison signal generated by the comparison circuit.

Abstract: A component inaccuracy correction system has a current source capable of outputting two currents with a fixed ratio, a voltage dividing circuit formed on the integrated circuit having at least an output end capable of receiving a current of the current source to output a divided voltage, a reference voltage generator capable of receiving another current of the current source to output a reference voltage, a comparison circuit electrically connected to the output end of the voltage dividing circuit for receiving the divided voltage from the voltage dividing circuit and comparing the divided voltage to the reference voltage to create a corresponding comparison signal, and a correction circuit electrically connected to the comparison circuit for correcting component inaccuracies of the integrated circuit according to the comparison signal generated by the comparison circuit.