Abstract: A quadrature phase shift keying (QPSK) modulating apparatus includes a bit splitter for dividing a bipolar input bit stream into first and second data streams, first and second binary phase shift keying (BPSK) modulators, and a combiner for combining output signals of the first and second BPSK modulators to obtain a QPSK modulated output. The first BPSK modulator includes a voltage-controlled first electrical source which receives the first data stream, and a first oscillator which includes a first resonator that has a first resonant frequency and that is excited by the first electrical source in response to the first data stream so as to generate a first sine wave output.