Transconductance-tunable radio-frequency digital-to-analog converter for dual-mode frequency translating ΔΣMs

In this paper, a Transconductance(gm)-tunable Radio-Frequency Digital-to-Analog converter (RFDAC) that used in Frequency Translating Delta-Sigma Modulator (FTDSM) is presented. The proposed RFDAC can support dualmode operation for FTDSM. To guarantee the linear gm control, constant current density technique is used. To verify the RFDAC, the prototype of 4th order FTDSM is fabricated using a 90 nm CMOS process and measured in the laboratory. The measured SNDR for 800 MHz/1.6 GHz dual mode operation was 43 dB and 44 dB for each.