A 120 pJ/bit $DeltaSigma$ -Based 2.4-GHz Transmitter Using FIR-Embedded Digital Power Amplifier

An energy efficient ${Delta Sigma }$ -based transmitter using the digital power amplifier (DPA) with the embedded FIR filtering is proposed in this brief. Compared to the conventional ${Delta Sigma }$ -based transmitters, the proposed architecture has the advantage of low power consumption with the DPA serving as the mixer, filter, and RF amplifier simultaneously. The embedded FIR filter provides improved suppression on the out-of-band quantization noise. The transmitter has been implemented in 0.18- $mu text{m}$ CMOS technology with a die area of 1.5 mm 2 . The fabricated transmitter consumes 2.37 mW power from 1.2-V power supply when outputting 20 Mb/s 64 QAM signal centered at 2.4 GHz with a power level of –15 dBm. The overall energy efficiency is 120 pJ/bit, which outperforms most of those recently published low power 2.4-GHz transmitters.