Abstract: A feedback control circuit of a pulse-frequency modulation (PFM) converter includes a multiplexer circuit and a detection circuit. The multiplexer circuit is arranged to receive a plurality of candidate peak current values, and output one of the plurality of candidate peak current values as a target peak current value according to a selection control signal, wherein a peak current value of an inductor current pulse of the PFM converter is subject to the target peak current value. The detection circuit is arranged to adaptively adjust the selection control signal according to a pulse interval between two successive inductor current pulses of the PFM converter.

Abstract: The invention provides a power amplifier circuit capable of adjusting gain dynamically. The power amplifier circuit comprises a power supply unit configured to provide a power supply signal; an input power detection unit for receiving at least one input signal and the power supply signal, detecting the power of the input signal to generate a detection signal, and pulling up or down a bias signal by the detection signal; a power amplifier unit for receiving the input signal and the bias signal, adjusting the gain by the controlling of the bias signal, and amplifying the input signal by the adjusted gain to output at least one output signal. Therefore, the gain of power amplifier circuit will be adjusted dynamically by detecting the power of the input signal, so that the output signal conforming to the actual power may be outputted.

Abstract: The invention provides a power amplifier circuit capable of adjusting gain dynamically. The power amplifier circuit comprises a power supply unit configured to provide a power supply signal; an input power detection unit for receiving at least one input signal and the power supply signal, detecting the power of the input signal to generate a detection signal, and pulling up or down a bias signal by the detection signal; a power amplifier unit for receiving the input signal and the bias signal, adjusting the gain by the controlling of the bias signal, and amplifying the input signal by the adjusted gain to output at least one output signal. Therefore, the gain of power amplifier circuit will be adjusted dynamically by detecting the power of the input signal, so that the output signal conforming to the actual power may be outputted.

Abstract: A bias circuit for the wireless transceiver is disclosed, which can be used for modulating the gain of the amplifier. The bias circuit comprises a first stage bias unit for receiving a constant current, a control voltage, and a first reference voltage and outputting a first outputting current, wherein the control voltage is used for controlling the value of the first outputting current, and further, the first outputting current can be increased or decreased by representing as an analog form, thus, the gain of the amplifier can be modulated according to the first outputting current, and the modulation of the gain can be represented as an analog form, such that the transient response occurred while the gain is modulated can be reduced.

Abstract: A bias circuit for the wireless transceiver is disclosed, which can be used for modulating the gain of the amplifier. The bias circuit comprises a first stage bias unit for receiving a constant current, a control voltage, and a first reference voltage and outputting a first outputting current, wherein the control voltage is used for controlling the value of the first outputting current, and further, the first outputting current can be increased or decreased by representing as an analog form, thus, the gain of the amplifier can be modulated according to the first outputting current, and the modulation of the gain can be represented as an analog form, such that the transient response occurred while the gain is modulated can be reduced.

Abstract: A wireless transmitter with temperature gain compensation includes a temperature sensor, a mixer, a power amplifier, a matching circuit, and an antenna. The mixer includes a mixer circuit and a gain compensation circuit. The gain compensation circuit includes a plurality of compensation units in parallel. Each compensation unit includes a resistor and a switch for turning on or off the switch to adjust the mixer's gain according to the sensed temperature of the temperature sensor. The wireless transmitter further includes a voltage gain control amplifier for choosing the output power of the transmitter.

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 radio frequency (RF) receiver is provided, comprising an antenna, a low noise amplifier, a down converter, a first analog to digital converter (ADC), a second ADC, a digital up converter. The antenna receives an RF signal, and the LNA coupled to the antenna amplifies the RF signal. The down converter, coupled to the LNA, down converts the RF signal to generate an in-phase baseband signal and a quadrature baseband signal. The first ADC, coupled to the down converter, digitizes the in-phase baseband signal to an in-phase digital signal. The second ADC, coupled to the down converter, digitizes the quadrature baseband signal to a quadrature digital signal. The digital up converter, coupled to the first and second ADCs, up converts the in-phase digital signal and quadrature digital signal to generate an intermediate frequency (IF) signal.

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 phase calibrating apparatus applied in a mixer includes a signal generator outputting a first signal and a second signal. The first signal has a phase differing by a phase value from the second signal. The phase calibrating apparatus is used to adjust the phase value to a predetermined value. The phase calibrating apparatus includes a multiplication unit and a comparator/controller unit. The multiplication unit has a multiplication of the first signal and the second signal to output a DC value corresponding to the phase value. The comparator/controller unit compares the DC value with a reference value and outputs a control signal. The signal generator adjusts the phase value according to the control signal until the phase value is substantially equal to the predetermined value.

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 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: 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?.