This paper presents a technique for improving the SNR and resolution of complex bandpass ∆ΣADCs which are used for wireless communication systems such as cellular phone, wireless LAN and Bluetooth. Oversampling and noise-shaping are used to achieve high accuracy of a ∆ΣAD modulator. However when a multi-bit internal DAC is used inside a modulator, nonlinearities of the DAC are not noise-shaped ...

Bandpass sampling is a useful alternative for direct digital downconversion in software radio. It significantly relaxes the analog-to-digital converter (ADC) sampling rate requirement and facilitates the design goal of moving the ADC as close as possible to the antenna. This paper presents a modified interpretation to the graph of allowable sampling frequencies in uniform bandpass sampling. It ...

Bandpass sampling is a useful alternative for direct digital downconversion in software radio. It significantly relaxes the analog-to-digital converter (ADC) sampling rate requirement and facilitates the design goal of moving the ADC as close as possible to the antenna. This paper presents a modified interpretation to the graph of allowable sampling frequencies in uniform bandpass sampling. It ...

A digital look-up table adaptive predistortion technique using a six-port receiver for power amplifier linearization is presented. The system is designed in Ka-band for a DVB-S2 satellite link. We use a six-port receiver at the linearizationloop in place of classic heterodyne receivers. The six-port receiver is implemented by the use of passive microwavecircuits and detector diodes. This approa...

A novel low noise trans-impedance amplifier is proposed using low cost 0.18 µm CMOS technology. A resistive-capacitive feedback is used to extend the bandwidth of the amplifier. As the structure is inductor less, it is suitable for low cost integrated optical interconnects. In this paper Improved Particle Swarm Optimization have applied to determine optimal trans-resistance and noise of propose...

Precise and representative power amplifier models are a key factor in order to simulate an entire communication system and essential in order to introduce linearization techniques (e.g., predistortion). This work analyses the distortion caused by power amplifiers driven by wideband signals. The traditional measures (AM-AM and AM-PM curves), characterizations and models (Saleh [1], Poza [2] and ...

A semi-physical behavioural high power amplifier model to characterize nonlinear distortion in mobile communication systems was introduced in [1]. The functional model is able to copy the low-voltage features of a real amplifier causing crossover distortion. Hence it gives an improved description of the nonlinearity of Class AB amplifiers widely used in mobile phones employing a linear modulati...

We report a new type of microstrip bandpass spiral filter structure, which exhibits much smaller size than other existing miniaturized bandpass filter structures, and is particularly useful in developing hightemperature superconducting (HTS) compact filters for cellular communication systems. A prototype three-stage HTS bandpass spiral filter with center frequency of 633 MHz was designed and fa...

Bandpass sampling allows for the digitisation of bandpass signals at RF or intermediate frequencies. This is desirable for reconfigurable radio systems, where, as many radio functions as possible should be defined in software to create a flexible transceiver. However, the effects of aperture jitter limit sampling at high carrier frequencies. This paper investigates the effects of jitter in band...