Bipul Agarwal

A progammable baseband anti-alias filter for a passive-mixer-based, SAW-less, multi-band, multi-mode WEDGE transmitter

A programmable baseband anti-alias filter (AAF) for a passive-mixer-based, 1.8V, SAW-less, multi-band, multi-mode WEDGE (WCDMA/HSUPA/EGPRS) cellular transmitter (TX) is described. This paper presents an AAF which results in ultra-low, −170dBc/Hz, receive-band noise, and enables the first single-mixer-based, multi-mode, SAW-less TX. By providing the noise and linearity performance only on-demand from system requirements, the presented AAF enables power savings of 14mW, or 34% of the total 41mW TX power. The AAF has been fabricated as part of a single-chip 0.13µm CMOS transceiver.

A CMOS dB-linear RF VGA for SAW-less WEDGE transmitters

A CMOS dB-linear RF variable gain amplifier (VGA) that can provide a variable gain of 25-dB is implemented. The 25-dB of this range is achieved by a dB-linear V-I converter, which includes current limiting circuitry to reduce the gain variation due to process and temperature at maximum and minimum output power levels. The circuits are designed in a 0.13-um RF CMOS process. The measurement results demonstrate −45 dBc ACLR, −165-dBc/Hz Rx-band noise at 5-dBm output power and 25-dB dynamic gain control range in UMTS band for WCDMA. The RF VGA consumes 30-mA of current at maximum gain from a 1.8-V supply.