A proposed simple DC offset cancellation method for low-power integrated circuits

Ultrawideband communications using impulse signal is recently one of the key technologies for wireless communications due to its feasibility to various applications. Ultra wideband (UWB) RF chaotic system, a modified UWB system, using noise-like signal has advantageous features including low power consumption, efficient power management, compactness, and robustness in multipath and thus lower price. Since UWB RF chaotic transceiver basically composed entirely of single ended output building block, operational amplifiers should be inverting or noninverting. In this paper, a programmable gain amplifier (PGA) was implemented by using a proposed simple DC offset voltage cancellation circuit, only for inverting or non-inverting operational amplifiers, and a 0.1 mum CMOS technology. The DC offset voltage cancellation circuit, a resistor, overcomes the classical DC offset problems that degrade the sensitivity performance of direct chaotic transceivers. The voltage gain is varied by digitally controlling the input switched resistors and the overall PGA gain varies from 22dB to 30dB with 1dB per step. With a 0.18mum CMOS technology, this work dissipates 0.81mW from a 1.8V supply voltage