Masaaki Tanio

A linear and efficient 1-bit digital transmitter with envelope delta-sigma modulation for 700MHz LTE

A highly linear and efficient 1-bit digital transmitter with envelope ΔΣ modulation (EDSM) is presented. Analyses and simulations reveal that the EDSM scheme is robust for distortion in output waveforms, and this has been experimentally verified using a CMOS EDSM IC and a GaN class-D PA for the 700-MHz band. The transmitter achieves an average ηD of 56.3% and an ACLR of -39 dBc for a 5-MHz BW and 6-dB PAPR LTE input without digital pre-distortion (DPD). Simple memoryless AM-PM correction is sufficient to improve ACLR to less than -45 dBc, indicating a lessening in required DPD.

Digital doherty transmitter with envelope ΔΣ modulated class-D GaN power amplifier for 800 MHz band

This paper presents a novel transmitter (Tx) architecture combining voltage-mode class-D power amplifiers (PAs) with an efficient 1-bit envelope delta-sigma modulation scheme for the 800 MHz band. By digitally processing the input 1-bit codes, the proposed Tx operates as a digital Doherty Tx. The proposed Tx architecture is realized with a GaN H-bridge class-D PA module and CMOS modulator ICs and delivers a CW power of 35.9 dBm at 860 MHz with a final-stage drain efficiency of 75.6% at the saturation point. The drain efficiency at 6-dB BO is still 73.4% which corresponds to an improvement of 23.9 points compared to balanced operation. Using a CDMA signal of 1-MHz bandwidth and 6.5-dB peak-to-average power ratio, the digital Doherty Tx achieves an average output power of 28.6 dBm with a drain efficiency of 56.5%.

An FPGA-based all-digital transmitter with 28-GHz time-interleaved delta-sigma modulation

An FPGA-based all-digital transmitter with 28-GHz ΔΣ-modulation is presented. For improving the operation frequency of ΔΣ modulator (DSM), a multi-channel look-ahead time-interleaved ΔΣ modulator is proposed. By implementing the proposed DSM in an FPGA, 28-GHz operation of DSM has been achieved. Furthermore, FPGA-based all-digital transmitter integrating the proposed DSM can satisfy the spectral mask of IEEE 802.11a WLAN standard in 5.2-GHz band. To the best of our knowledge, this is the first demonstration of an FPGA-based all-digital transmitter which can directly generate 5-GHz band WLAN signal.

Wireless D-band communication up to 60 Gbit/s with 64QAM using GaAs HEMT technology

Over 40-Gbps wireless communication in the D-band is described. 120-GHz-band transmitter and receiver modules employing direct modulation architecture are developed using 70-nm mHEMT technology for a RF amplifier and 0.1-μm pHEMT technology for an IQ modulator and a frequency doubler. The developed modules successfully demonstrate 64QAM transmission with a data rate of 42 Gbit/s occupying a bandwidth of less than 10 GHz (spectrum efficiency of 4.92 bit/s/Hz) and a BER of less than 10-3. The feasibility of 60 Gbps wireless transmission is also verified. To the best of our knowledge, this is the first time that over 40-Gbps D-band communication using a practical bandwidth of less than 10 GHz is achieved.

An FPGA-based all-digital transmitter with 9.6-GHz 2nd order time-interleaved delta-sigma modulation for 500-MHz bandwidth

An FPGA-based all-digital transmitter with 9.6-GHz 2nd order Time-Interleaved ΔΣ-modulation (TI-DSM) is presented. To improve the operation frequency of TI-DSM, bit separation architecture is proposed. This proposed architecture realizes the 1-bit digital transmitter with 500-MHz bandwidth. This is the widest bandwidth modulation among state-of-the-art FPGA-based all-digital transmitters.

A digital radio-over-fiber downlink system based on envelope delta-sigma modulation for multi-band/mode operation

A digital radio-over-fiber (DRoF) downlink system using envelope delta-sigma modulation (EDSM) for multimode/band applications is presented. Analyses and simulations reveal that the EDSM scheme increases tolerance to jitter introduced by optical components. This has been verified and demonstrated with a DRoF link using CMOS EDSM IC. As a result of the improvement, this system successfully meets major 3GPP LTE bands from 760 MHz to 2.6 GHz as well as IEEE 802.11g WLAN standard requirement.