Design of a 0.18μm Low-Voltage Switched-Current ΣΔ Modulator for Multistandard Communication Systems

This paper presents a 1.8-V, 0.18μm CMOS reconfigurable switched-current ΣΔ modulator for multistandard (GSM, Bluetooth, WCDMA) telecom systems. The modulator topology is an expandable cascade architecture which can be reconfigured both at the architecture level and at the circuit level in order to adapt the modulator performance to the different standards with adjustable power consumption. For this purpose, programmable Class AB memory-cell arrays are used to implement the modulator loop filter. Transistor-level simulations are shown that demonstrate correct operation for all standards, featuring 12-bit, 11-bit and 7.8-bit dynamic range within 200-kHz, 1-MHz and 3.8-MHz bandwidth, respectively.