title: Analysis of circuit conditions for optimum intermodulation and gain in bipolar cascomp amplifiers with non-ideal error correction

authors: Balsom, Toby

abstract: The cascoded-compensation or ‘Cascomp’ amplifier offers excellent distortion reduction and thermal distortion rejection, but has not seen widespread use because of a limited gain and increased complexity compared with other topologies. The original theory showed that with the addition of an ideal error amplifier the circuit will completely compensate distortion for suitably chosen degeneration and bias values. This research presents a new, rigorous mathematical proof for conditions of compensation. The authors further develop the proof to include the non-idealities of the error amplifier. It is shown that there exists a second bias point, not exposed by the original analysis that offers improved gain while maintaining distortion cancellation. By reducing the error amplifier degeneration resistance, one can increase a Cascomp circuit's overall gain by several dB while maintaining theoretically perfect distortion compensation. A robust bias point is proposed, which takes the advantage of this new theory by optimising circuit values resulting in a comparatively broader and deeper third-order distortion null. The proposed theory is confirmed with simulation and measurement that show agreement within the bounds of process and component error limits.

text: Analysis of circuit conditions for optimum intermodulation and gain in bipolar cascomp amplifiers with non-ideal error correction The cascoded-compensation or ‘Cascomp’ amplifier offers excellent distortion reduction and thermal distortion rejection, but has not seen widespread use because of a limited gain and increased complexity compared with other topologies. The original theory showed that with the addition of an ideal error amplifier the circuit will completely compensate distortion for suitably chosen degeneration and bias values. This research presents a new, rigorous mathematical proof for conditions of compensation. The authors further develop the proof to include the non-idealities of the error amplifier. It is shown that there exists a second bias point, not exposed by the original analysis that offers improved gain while maintaining distortion cancellation. By reducing the error amplifier degeneration resistance, one can increase a Cascomp circuit's overall gain by several dB while maintaining theoretically perfect distortion compensation. A robust bias point is proposed, which takes the advantage of this new theory by optimising circuit values resulting in a comparatively broader and deeper third-order distortion null. The proposed theory is confirmed with simulation and measurement that show agreement within the bounds of process and component error limits.

year: 2014-11-20

title: Evaluating and using remote sensing data for studying economic activity and population change in China

authors: Zhang, Xiaoxuan

abstract: use of remote sensing data, especially night-time lights (NTL) data, has flourished
in recent decades as a proxy for measuring economic activity and the spatial distribution
of population. The availability of these data can make up for the absence of and possible
inaccuracy in traditional economic statistics, especially because NTL data are available
at fine scale and with high frequency. The growing use of these data raises the question
of how accurate is this night-time lights proxy, and for what purposes is it best suited
when studying economic development and population changes at sub-national levels.
In the first part of this thesis, a 20-year time-series of GDP at China’s third
sub-national level (counties, county-level cities and districts) and census population
counts at the same level from 2000, 2010 and 2020, are used as a benchmark to examine
the performance of multiple sources of NTL data as proxies for local economic activity
and inequality. I also test the accuracy of gridded population estimates, some of which
rely on NTL data, for estimating inter-census changes in local population.
Based on the comprehensive evaluation of different NTL sources at different levels of
spatial aggregation, the second part of the thesis uses NTL and other remote sensing
data, in conjunction with the traditional GDP and population statistics, to study a set of
economic issues that are pertinent to regional development in China. The impact of
administrative upgrading of county-level units (a type of regional policy practiced in
China) and of modern transport infrastructure is studied, using both GDP and NTL data
to measure economic impacts. These studies use spatial econometric models that allow
for spillovers. The changes in the city size distribution, in terms of land and people, is
also studied because of the possibility that China’s cities are physically expanding in
places other than where the population is moving.
Overall, the thesis contributes a nuanced understanding of how NTL data and
other remote sensing data can assist in studying complex social and economic problems,
as well as raising some caveats about the limits to the uses of such data.

text: Evaluating and using remote sensing data for studying economic activity and population change in China use of remote sensing data, especially night-time lights (NTL) data, has flourished
in recent decades as a proxy for measuring economic activity and the spatial distribution
of population. The availability of these data can make up for the absence of and possible
inaccuracy in traditional economic statistics, especially because NTL data are available
at fine scale and with high frequency. The growing use of these data raises the question
of how accurate is this night-time lights proxy, and for what purposes is it best suited
when studying economic development and population changes at sub-national levels.
In the first part of this thesis, a 20-year time-series of GDP at China’s third
sub-national level (counties, county-level cities and districts) and census population
counts at the same level from 2000, 2010 and 2020, are used as a benchmark to examine
the performance of multiple sources of NTL data as proxies for local economic activity
and inequality. I also test the accuracy of gridded population estimates, some of which
rely on NTL data, for estimating inter-census changes in local population.
Based on the comprehensive evaluation of different NTL sources at different levels of
spatial aggregation, the second part of the thesis uses NTL and other remote sensing
data, in conjunction with the traditional GDP and population statistics, to study a set of
economic issues that are pertinent to regional development in China. The impact of
administrative upgrading of county-level units (a type of regional policy practiced in
China) and of modern transport infrastructure is studied, using both GDP and NTL data
to measure economic impacts. These studies use spatial econometric models that allow
for spillovers. The changes in the city size distribution, in terms of land and people, is
also studied because of the possibility that China’s cities are physically expanding in
places other than where the population is moving.
Overall, the thesis contributes a nuanced understanding of how NTL data and
other remote sensing data can assist in studying complex social and economic problems,
as well as raising some caveats about the limits to the uses of such data.

year: 2024

title: Exploring te ao Māori: The role of museums

authors: Clarkin-Phillips, Jeanette

subjects: museum

abstract: Museums offer many opportunities for developing knowledge of the bicultural heritage of Aotearoa New Zealand. This article reports on research involving a kindergarten located in a national museum. It discusses children’s growing understanding of te ao Māori (the world of Māori) through their regular visits to the collections and exhibits in the museum and suggests teachers in early childhood centres may find connecting with their local museum a valuable resource for enhancing bicultural practice.

text: Exploring te ao Māori: The role of museums Museums offer many opportunities for developing knowledge of the bicultural heritage of Aotearoa New Zealand. This article reports on research involving a kindergarten located in a national museum. It discusses children’s growing understanding of te ao Māori (the world of Māori) through their regular visits to the collections and exhibits in the museum and suggests teachers in early childhood centres may find connecting with their local museum a valuable resource for enhancing bicultural practice.

year: 2012