The following original contributions can be found in this thesis and related publications:

• The S/N and power analysis in fixed point digital filters presented in Chapter 2 and APPENDIX 1 with the architectural approach of power.

• The DR*Speed concept and its use in finding minimum power consumption in analog circuits continuous time or sampled data. The analysis of analog filters is also an example where the same concept can be used in analysis of an analog system. The same concept has been used further in the thesis in some other applications. It was also used to see the effects of power supply voltage down-scaling in modern processes ant its impact on voltage or current processing circuits.

• The transconductor presented in Chapter 4 is a new concept capable to cope with second order effects in modern MOS transistors. The large swing property and the constant window, independent of tuning, are also used in making a design for mixed level applications.

• The linearity improvement of the current Gm-C integrator and the use of resistor degeneration to improve matching.

• The gaussian polyphase filter based on current Gm-C integrator is a new concept which shows an improvement with a factor 6 in power when compared to opamp based designs. At the same time is the first material showing how a gaussian filter can be used to achieve selectivity in receivers.

• The chopper principle from Chapter 3 destinated for high frequency chopping up to 1MHz. This chopped transconductance amplifier can be used for low frequency applications as well as high frequency applications.

• The principle of accuracy improvement of a bandgap reference voltage circuit by using chopped amplifiers without the need of external filter.

• The chopped amplifers with class AB output stages where chopping the OTA and a part of the bias current shared in common by the OTA and the class AB output stage will improve the accuracy of the complete amplifier. The class AB stage of the chopped amplifier in 0.5mm CMOS is also a new circuit.

• The Sinc approximation method in time or frequency domain and its use in D/A converters. The differential approach and the floating mirror used to improve accuracy combined with the reduction of the number of coefficients in the filtering part are also new items.

• The noise and jitter analysis for the performance of the D/A interface.