Extraction plays an important role in the performance of device models especially in the high frequency regime. The present day extraction techniques mostly use a grounded source or common source (CS) device configuration. The models extracted from the grounded source devices are then used for devices in other configurations in a circuit application. This leads to discrepancies in accurate prediction of the circuit performance. This work investigates, the applicability of the models extracted using CS for other device configurations. It was shown with the help of measured data, in the frequency range of 1-20 GHz, that the models extracted from CS configuration do not predict the performance of a device in common drain (CD) configuration. Based on the above observation, a universal gate impedance model that works for both CS and CD configurations for BSIM3v3 was developed. The gate impedance model was then extended to BSIM4 for both CS and CD configurations. The models for BSIM3v3 and BSIM4 are verified using simulations and compared with the measured data.

Four discrete orthogonal transforms have been evaluated for their suitability for use in transform-based analog speech encryption. Subjective as well as objective tests were conducted to compare the residual intelligibility and the recovered speech quality under channel conditions. The cryptanalytic strengths of the schemes were then compared by applying a novel cryptanalytic attack which exploits the redundancy of speech using a spectral vector codebook. The results indicate that the discrete cosine transform (DCT) is the best transform to use in transform-based encryption. A modification of the DCT-based scheme which significantly improves the security of the scrambler is proposed.>

The performances of five discrete orthogonal transforms in speech encryption systems are compared. The transforms considered are the discrete Fourier transform, discrete cosine transform, Walsh-Hadamard transform, Karhunen-Loeve transform, and discrete prolate spheroidal transform. Four objective measures are used to grade the encryption systems with respect to residual intelligibility and recovered voice quality. A figure of merit based on all the four objective measures is formed. It gives good correlation to the subjective results of residual intelligibility and recovered speech quality.>

A method of applying residue feedback in three digital ladder and lattice filter structures is proposed. It is shown that residue feedback leads to significant improvement in both the round-off noise characteristics and limit cycle behaviour. In particular the residue compensated one multiplier structure is superior to the (uncompensated)normalized ladder. This results in significant savings in both hardware and speed of implementation.