Abstract: A circuit capable of automatically calibrating a resonant frequency of an antenna includes the antenna, a switch, a conversion unit, a count comparator, and a capacitor array. The switch is coupled to the antenna for being turned on and turned off according to a pulse. The antenna is used for generating the resonant frequency according to on and off of the switch. The conversion unit is coupled to the antenna for generating a clock according to a signal with the resonant frequency. The count comparator is coupled to the conversion unit for counting a number generated by a reference clock during a period of the clock, and comparing the pulse number with a predetermined value to generate an adjustment signal. The capacitor array is used for adjusting capacitance of the capacitor array according to the adjustment signal.

Abstract: A circuit for generating a direct current voltage includes a three-axis antenna set, a first capacitor, a limiting direct current voltage generator, a second capacitor, and a low dropout regulator. The three-axis antenna set receives a signal transmitted by a reader. The first capacitor generates a first direct current voltage according to an X-axis component, a Y-axis component, and a Z-axis component of the signal. The limiting direct current voltage generator limits and converts the X-axis component, the Y-axis component, and the Z-axis component to generate an X-axis direct current voltage, a Y-axis direct current voltage, and a Z-axis direct current voltage. The second capacitor generates a second direct current voltage according to the X-axis direct current voltage, the Y-axis direct current voltage, and the Z-axis direct current voltage. The low dropout regulator generates a direct current output voltage according to the second direct current voltage.

Abstract: A high efficiency driving circuit includes a first P-type metal-oxide-semiconductor transistor, a second P-type metal-oxide-semiconductor transistor, a first N-type metal-oxide-semiconductor transistor, a second N-type metal-oxide-semiconductor transistor, a current source, a third N-type metal-oxide-semiconductor transistor, a fourth N-type metal-oxide-semiconductor transistor, a fifth N-type metal-oxide-semiconductor transistor, a first resistor, and a second resistor. The first P-type metal-oxide-semiconductor transistor charges a third terminal of the first P-type metal-oxide-semiconductor transistor according to a first control signal, and the first N-type metal-oxide-semiconductor transistor discharges the third terminal of the first P-type metal-oxide-semiconductor transistor according to a second control signal.

Abstract: An electronic oscillation signal generation circuit includes an electronic oscillation circuit, a DC voltage source for providing a DC voltage to the electronic oscillation circuit, a switch for electrically connecting the electronic oscillation circuit to ground when the switch is turned on so as to generate an analog oscillation signal after the switch is turned off, a conversion circuit for converting the analog oscillation signal to a digital oscillation signal, a counter for generating a control signal when the digital oscillation signal reaches a predetermined number of periods, a delay unit for generating a delay signal a predetermined time after a falling edge of the digital oscillation signal is triggered, and a pulse signal generation circuit electrically connected to the counter and the delay unit for generating a pulse signal according to the control signal and the delay signal so as to turn on the switch.

Abstract: A receiver includes a radio frequency metal-oxide-semiconductor amplifier, a mixer, and an intermediate frequency amplifier. The radio frequency metal-oxide-semiconductor amplifier is used for receiving amplifying a signal of a first band and a signal of a second band of a satellite microwave band from an external antenna circuit according to a control signal. The mixer is coupled to the radio frequency metal-oxide-semiconductor amplifier for reducing the signal of the first band to a signal of a first intermediate frequency band according to a first oscillation frequency of a local oscillator, or reducing the signal of the second band to a signal of a second intermediate frequency band according to a second oscillation frequency of the local oscillator. The intermediate frequency amplifier is coupled to the mixer for amplifying and outputting the signal of the first intermediate frequency band and the signal of the second intermediate frequency band.