PSK Modulator for Regenerative Sampling Gigabit UWB Communication

Abstract:
To achieve high data rates in ultra-wideband communication systems, complex pulse modulation schemes like high order phase shift keying (PSK) are required in order to increase spectral efficiency. In this work, a synthesizer concept based on a passive switched-line phase modulator is introduced where both the modulation control and the RF carrier signal are provided by standard digital drivers. A high switching speed of 400 MHz at 6 GHz carrier frequency is achieved using Schottky diode switches to deliver a 1.2 GBit/s throughput using a 3-bit modulator (8-PSK). The switched injection-locked oscillator – as the only active RF element for pulse generation with phase regeneration from a weak injected signal – allows for both high insertion losses (11 dB) at the phase modulator as well as RF carrier generation from a low power harmonic of a baseband signal. The result is a PSK UWB transmitter with low power consumption and low system complexity, without any need for RF PLL, linear amplifiers, DACs or an analog baseband.