Abstract: A double frequency-shift keying modulating device includes a modulation module. The modulation module receives an oscillating signal and a digital signal, and generates a modulation output signal that has a first frequency. The first frequency is associated with a frequency of the oscillating signal and varies periodically at a second frequency. The second frequency is associated with the digital signal and the frequency of the oscillating signal.

Abstract: A double frequency-shift keying modulating device includes a modulation module. The modulation module receives an oscillating signal and a digital signal, and generates a modulation output signal that has a first frequency. The first frequency is associated with a frequency of the oscillating signal and varies periodically at a second frequency. The second frequency is associated with the digital signal and the frequency of the oscillating signal.

Abstract: A balanced up-conversion mixer includes: a load circuit permitting a differential radio frequency (DRF) current signal pair (SP) to flow out and outputting a DRF voltage SP based on its impedance, a DC bias voltage and the DRF current SP; a mixing circuit allowing the DRF current SP to flow thereinto based on a differential intermediate frequency voltage SP, a differential oscillating voltage SP generated based on an oscillating voltage signal by a single-ended to differential conversion circuit, and first and second currents generated by a negative resistance compensation circuit based on a DC bias voltage; and a signal amplifier circuit amplifying the DRF voltage SP to generate a differential output voltage SP.