Ultra-low power high bandwidth QPSK modulator

A novel method to produce direct QPSK modulation is presented. The key feature of the architecture is the absence of mixers and as a result unwanted mixing products. Bandwidth limitations of previous designs are overcome with a novel phase shifting technique. A prototype is demonstrated at 2.4 GHz to showcase the performance of the modulator. An error vector magnitude (EVM) of less than 5% is obtained over a 600 MHz bandwidth. The power consumption of the circuit is less than 10 muW and its 1 dB compression point is 17 dBm.