Low-power CMOS fully integrated transmitters exploiting on-chip antennas

Two different integrated transmitter typologies, each exploiting an on-chip loop antenna and implementing an on-off key (OOK) modulation, have been implemented using a standard 0.35 μm CMOS process. The implemented transmitters use two different directly modulated oscillator topologies, namely a 2.5 GHz complementary cross-coupled LC oscillator and a 1 GHz current-starved ring oscillator, whose outputs are employed respectively to feed their own loop antenna. The cross-coupled LC transmitter and the ring oscillator topology consume, respectively, 22 mW and 4.4 mW from 3.3 V supply voltage. The average power consumption can be decreased to few tens of microwatt by duty-cycling the transmitters and by increasing the data rate of the packet to be transmitted up to 2 Mbit/s for the cross-coupled LC typology and 1 Mbit/s for the ring oscillator transmitter. The employed integrated small loop antennas radiate sufficient power for few meters communication range.