A multi-emission frequency domain modulator

The development of mobile and portable multi-emission transceivers for analog and digital transmission over a wide frequency range requires the development of integrated modulator and demodulator systems. An experimental multi-emission frequency domain modulator that operates in the frequency range from approximately 5 MHz to 1 GHz is described. Using passive integrated components such as splitters, hybrids, and double-balanced mixers, as well as monolithic broadband amplifiers, the modulator modulates a carrier with a baseband signal in AM, SSB, DSB, FM, PM, or a variety of n-phase-shift keying (PSK)-modes. The analog modulations are generated using frequency domain techniques, i.e., the carrier and each sideband pair are independently generated. The n-PSK modes are developed by combining inphase, ±90°, and 180° components using amplifiers/attenuators and an in-phase combiner. The performance of this modulator is discussed, as well as extensions to this technique to wideband FM, spread spectrum, and demodulation. Suitable architectures for a transceiver that incorporates this circuit, including integration of this modulator into a monolithic package, are considered