Abstract: The present invention discloses an amplifier. The bias amplifier includes a signal input end, for inputting an input signal; a voltage input end, for inputting a source voltage; an amplifying circuit, for generating an amplified input signal according to the input signal, and the amplified input signal comprises a fundamental signal, a first harmonic signal and a second harmonic signal, wherein the first harmonic signal is a second order harmonic of the fundamental signal, and the second harmonic signal is a third order harmonic of the fundamental signal; a harmonic filter, coupled between the voltage input end and the amplifying circuit, for filtering the first harmonic signal and the second harmonic signal; and a signal output end, coupled to the harmonic filter, for outputting an output signal according to the amplified input signal.

Abstract: A bias device includes a transistor, a bias circuit, and an impedance unit. The transistor has a first terminal, a second terminal for providing a first bias voltage to an input terminal of an amplifier, and a control terminal. The bias circuit has a first terminal, a second terminal coupled to a first system voltage terminal for receiving a first system voltage, and a third terminal coupled to the control terminal of the first transistor for providing a second bias voltage to the control terminal of the first transistor. The impedance unit has a first terminal for receiving a first reference voltage, a second terminal coupled to the first terminal of the bias circuit. The first impedance unit adjusts the input impedance looking into the second terminal of the first transistor according to a frequency of a radio frequency signal received from the input terminal of the amplifier.

Abstract: A bias circuit includes a current sensor, a transistor, and a low pass filter circuit. The current sensor has a first terminal coupled to a voltage terminal, and a second terminal. The transistor has a first terminal coupled to the second terminal of the current sensor, a second terminal coupled to a radio frequency signal path for providing a bias signal, and a control terminal for receiving a reference voltage. The low pass filter circuit is coupled between the second terminal of the current sensor and the control terminal of the transistor.

Abstract: A bias device includes a transistor, a bias circuit, and an impedance unit. The transistor has a first terminal, a second terminal for providing a first bias voltage to an input terminal of an amplifier, and a control terminal. The bias circuit has a first terminal, a second terminal coupled to a first system voltage terminal for receiving a first system voltage, and a third terminal coupled to the control terminal of the first transistor for providing a second bias voltage to the control terminal of the first transistor. The impedance unit has a first terminal for receiving a first reference voltage, a second terminal coupled to the first terminal of the bias circuit. The first impedance unit adjusts the input impedance looking into the second terminal of the first transistor according to a frequency of a radio frequency signal received from the input terminal of the amplifier.

Abstract: A bias circuit includes a current sensor, a transistor, and a low pass filter circuit. The current sensor has a first terminal coupled to a voltage terminal, and a second terminal. The transistor has a first terminal coupled to the second terminal of the current sensor, a second terminal coupled to a radio frequency signal path for providing a bias signal, and a control terminal for receiving a reference voltage. The low pass filter circuit is coupled between the second terminal of the current sensor and the control terminal of the transistor.

Abstract: A protection circuit for use in an RF active circuit includes a signal strength detecting circuit, a current detecting circuit, a logic circuit, and a switching unit. The signal strength detecting circuit is coupled to the signal input end or the signal output end of the RF active circuit and configured to generate a first detecting signal according to the signal strength of the RF signal. The current detecting circuit is configured to detect the VSWR of the RF signal based on the driving current of the RF active circuit, thereby generating a corresponding second detecting signal. The logic circuit is configured to generate a switch control signal according to the first detecting signal and the second detecting signal. The switching unit is configured to lower the driving current of the RF active circuit according to the switch control signal.

Abstract: A protection circuit for use in an RF active circuit includes a signal strength detecting circuit, a current detecting circuit, a logic circuit, and a switching unit. The signal strength detecting circuit is coupled to the signal input end or the signal output end of the RF active circuit and configured to generate a first detecting signal according to the signal strength of the RF signal. The current detecting circuit is configured to detect the VSWR of the RF signal based on the driving current of the RF active circuit, thereby generating a corresponding second detecting signal. The logic circuit is configured to generate a switch control signal according to the first detecting signal and the second detecting signal. The switching unit is configured to lower the driving current of the RF active circuit according to the switch control signal.

Abstract: A calibration circuit includes at least two compensation circuits and a comparator. The at least two compensation circuits are coupled to an input signal for outputting at least a first compensation signal and a second compensation signal respectively. The comparator is coupled to the first compensation signal and the second compensation signal for outputting a calibration signal, where the calibration signal is used for determining an oscillation frequency of a crystal oscillator to achieve a purpose of frequency compensation with a temperature.

Abstract: A calibration circuit includes at least two compensation circuits and a comparator. The at least two compensation circuits are coupled to an input signal for outputting at least a first compensation signal and a second compensation signal respectively. The comparator is coupled to the first compensation signal and the second compensation signal for outputting a calibration signal, where the calibration signal is used for determining an oscillation frequency of a crystal oscillator to achieve a purpose of frequency compensation with a temperature.

Abstract: A multi-band electronic apparatus and method thereof is provided. The method comprises outputting a first output signal in the first band by a first voltage controlled oscillator according to a switch control signal and a control voltage, outputting a second output signal in the second band by a second voltage controlled oscillator according to the switch control signal and the control voltage, the second band being not completely overlapped by the first band, performing frequency division selectively on the first output signal or the second frequency divided signal according to the switch control signal, and outputting a first frequency divided signal, determining a phase difference between the first frequency divided signal and a reference signal to output a phase difference signal, outputting the control voltage according to the phase difference signal, and selectively driving the first or the second voltage controlled oscillators by the control voltage according to the switch control signal.

Abstract: A multi-band electronic apparatus and method thereof is provided. The method comprises outputting a first output signal in the first band by a first voltage controlled oscillator according to a switch control signal and a control voltage, outputting a second output signal in the second band by a second voltage controlled oscillator according to the switch control signal and the control voltage, the second band being not completely overlapped by the first band, performing frequency division selectively on the first output signal or the second frequency divided signal according to the switch control signal, and outputting a first frequency divided signal, determining a phase difference between the first frequency divided signal and a reference signal to output a phase difference signal, outputting the control voltage according to the phase difference signal, and selectively driving the first or the second voltage controlled oscillators by the control voltage according to the switch control signal.

Abstract: The invention is a process for stereoselectively producing a dioxolane nucleoside analogue from an anomeric mixture of &bgr; and &agr; anomers represented by the following formula A or formula B: wherein R is selected from the group consisting of C1-6 alkyl and C6-15 aryl and Bz is benzoyl. The process comprises hydrolyzing said mixture with an enzyme selected from the group consisting of Protease N, Alcalase, Savinase, ChiroCLEC-BL, PS-30, and ChiroCLEC-PC to stereoselectively hydrolyze predominantly one anomer to form a product wherein R1 is replaced with H. The process also includes the step of separating the product from unhydrolyzed starting material. Additionally, the functional group at the C4 position is stereoselectively replaced with a purinyl or pyrimidinyl or derivative thereof.

Abstract: The invention is a process for stereoselectively producing a dioxolane nucleoside analogue from an anomeric mixture of &bgr; and &agr; anomers represented by the following formula A or formula B: 1

Abstract: The invention is a process for stereoselectively producing a dioxolane nucleoside analogue from an anomeric mixture of &bgr; and &agr; anomers represented by the following formula A or formula B: wherein R is selected from the group consisting of C1-6 alkyl and C6-15 aryl and Bz is benzoyl. The process comprises hydrolyzing said mixture with an enzyme selected from the group consisting of Protease N, Alcalase, Savinase, ChiroCLEC-BL, PS-30, and ChiroCLEC-PC to stereoselectively hydrolyze predominantly one anomer to form a product wherein R1 is replaced with H. The process also includes the step of separating the product from unhydrolyzed starting material. Additionally, the functional group at the C4 position is stereoselectively replaced with a purinyl or pyrimidinyl or derivative thereof.

Abstract: The invention is a process for stereoselectively producing a dioxolane nucleoside analogue from an anomeric mixture of &bgr; and &agr; anomers represented by the following formula A or formula B: 1

Abstract: A process for irreversible regio- and stereoselective enzyme catalyzed acylation of alcohols using enol esters as acylating reagents is disclosed. The present invention permits the selective modification of hydroxyl group(s) of chiral and meso alcohols, including sugars, organometallics, and glycosides. The enol freed upon transesterification rapidly tautomerizes to the corresponding volatile aldehyde or ketone thereby preventing the reverse reaction from occurring.

Abstract: A new and practical method for synthesizing heterocyclic polyhydroxylated alkaloids using enzymatic aldol condensation and catalytic intramolecular reductive amination is disclosed.

Abstract: A new and practical method for synthesizing heterocyclic polyhydroxylated alkaloids using enzymatic aldol condensation and catalytic intramolecular reductive amination is disclosed.

Abstract: A process for irreversible regio- and stereoselective enzyme catalyzed acylation of alcohols using enol esters as acylating reagents is disclosed. The present invention permits the selective modification of hydroxyl group(s) of chiral and meso alcohols, including sugars, organometallics, and glycosides. The enol freed upon transesterification rapidly tautomerizes to the corresponding volatile aldehyde or ketone thereby preventing the reverse reaction from occurring.