Advanced Class-S transmitter with tri-level delta-sigma modulator

An advanced Class-S transmitter based on a tri-level delta-sigma modulator (DSM) is presented. The second order DSM shows a signal-to-noise and distortion ratio (SNDR) of 44.7 dB and a spurious-free dynamic range (SFDR) of 63.6 dB with a 3.1-MHz sinusoidal input at 522.24-MS/s using an offset cancellation scheme. The proposed technique improves the SFDR and SNDR over 10 dB and 3 dB, respectively. The proposed scheme can effectively control the input referred offset voltage of the DSM, resulting in the improvement of spectrum efficiency. The power consumption of the modulator is 13.4 mW from a 1.2 V supply. Measurements with a mixer show that the proposed modulator modulates a 10-MHz long-term evolution signal which has an 8.5 dB peak-to-average ratio with 3.30 % error vector magnitude and 38.7 dB adjacent channel leakage ratio at 2.6 GHz.