The recent demand for wireless transceivers has created a flurry of research into nontraditional
receiver architectures. The homodyne receiver, because of its high degree of
integration, low complexity and low power consumption, has surfaced a desirable alternative
to the well-known heterodyne receiver. However, distortions such as gain and phase
imbalance...
The tremendous growth of wireless and mobile communications has resulted in placing of stringent requirements on the channel spacing and, by implication, on the phase noise of oscillators, typically mandating the use of passive LC oscillators with high quality factor (Q). However the trend towards large-scale integration and low cost...
Direct-conversion architecture would dominate the modern low power wireless receiver architecture if problems such as offset cancellation, even-order distortion, and flicker noise were solved. Among those problems, offset is the most serious one. This thesis will discuss and analyze one approach to cancel offsets in direct-conversion receivers. First, we explain...
The thesis presents a new algorithm and structure that is to be used in conjunction with a specially modified CMOS Gilbert cell mixer to remove time-varying DC offsets in direct conversion receivers. In our approach, the DC offset is detected at the output of the mixer using a dedicated coarse...
Dynamic DC offset is one of the biggest problems preventing the implementation of single chip receivers. This thesis presents a 2.4GHz downconversion mixer designed to work with adaptive DC offset cancellation for a fully integrated direct conversion receiver. Offset can be removed by dynamically changing the PFET load bias in...
The importance of spectral efficiency in mobile communications often requires the use of non-constant-envelop linear digital modulation schemes. These modulation techniques carry signal information in both magnitude and phase, thus they must be linearly amplified to avoid nonlinear signal distortion which is not correctable in a typical receiver. A second...
We present a new circuit design for adaptive offset cancellation in a fully differential 2.4 GHz CMOS direct conversion mixer. Our circuit structure is a modification of a Gilbert cell mixer in which offsets are cancelled by injecting cancellation currents into the legs of the mixer by dynamically varying the...
Exposure to urban outdoor air pollution is ubiquitous and low birth weight represents an important health disparity in the United States. While previous research suggests that exposure to outdoor air pollutants are associated with term low birth weight, few studies have evaluated the effects of multipollutant outdoor air exposures or...