Highly integrated direct conversion receiver for GSM/GPRS/EDGE with on-chip 84-dB dynamic range continuous-time /spl Sigma//spl Delta/ ADC

This paper describes a highly digitized direct conversion receiver of a single-chip quadruple-band RF transceiver that meets GSM/GPRS and EDGE requirements. The chip uses an advanced 0.25-/spl mu/m BiCMOS technology. The I and Q on-chip fifth-order single-bit continuous-time sigma-delta (/spl Sigma//spl Delta/) ADC has 84-dB dynamic range over a total bandwidth of /spl plusmn/135 kHz for an active area of 0.4 mm/sup 2/. Hence, most of the channel filtering is realized in a CMOS IC where digital processing is achieved at a lower cost. The systematic analysis of dc offset at each stage of the design enables to perform the dc offset cancellation loop in the digital domain as well. The receiver operates at 2.7 V with a current consumption of 75 mA. A first-order substrate coupling analysis enables to optimize the floor plan strategy. As a result, the receiver has an area of 1.8 mm/sup 2/.     

Continuous active T-gate travelling-wave transistor

In the letter experimental results are presented which show that a continuous active gate travelling-wave transistor (TWT) can be used for medium power applications in a wide bandwidth. To reduce the gate resistance, a T-gate configuration has been chosen. This allows one to extend the frequency bandwidth of such a device. Simulations have been performed using small- and large-signal models taking in addition the parasitic capacitances into account. A distributed Schottky diode has been used to adjust the phase synchronisation and therefore to achieve flat gain.<>     

Performances des amplificateurs distribués en régime grand signal

This paper deals with the application of distributed amplifier as a power amplifier. Theoretical results obtained by using thespice II program will be presented and compared with measurements up to 12 GHz. It will be shown that small signal properties can be applied for large signal conditions. Large signal measurements give a constant gain of 6 dB in a frequency range from 1 to 10 GHz with an output power of 19 dBm.     

Large-signal capabilities and analysis of distributed amplifiers

In the letter experimental results are presented which show that distributed amplifiers can be used for power applications. These results are verified by comparing an analytic model predicted using SPICE 2 simulation with measurements between 0.3 and 12 GHz. It appears that a very broad band can be achieved and that the distributed amplifiers keep their self matching properties even under large-signal operation. Distributed-amplifier characteristics, under small-signal operations, are now well known.1?4 However, recent improvements in GaAs FET technology have created new prospects in large-signal and high-frequency conditions. To our knowledge, although some experimental results have been published3, no theoretical study has been carried out for large-signal conditions. The letter provides such a study.     

Low-power digitally-controlled variable gain attenuator and LNA with high gain dynamic range for sub-GHz ISM bands

A low-power Digitally-controlled Variable Gain Attenuator and Low Noise Amplifier are implemented in a 40-GHz f_T 0.25-??m BiCMOS process. They cover the sub-GHz ISM bands for automotive applications such as Remote Keyless Entry. The LNA achieves wideband input matching independent of the variable gain, as well as high reverse isolation, thanks to a partial feedback technique. Its variable gain is based on a resistor-chain gain-control technique, leading to fine gain steps and constant output impedance. This LNA is designed with 15 gain steps of 1?dB. The simulated results for the maximum gain show a Transducer Power Gain of 16.5?dB, a Noise Figure of 2.4?dB and respective input and output IP₃ of ?12.1 and +4.5?dBm, while only drawing 1.45?mA from a 2.7?V power supply. The measurement results are slightly degraded because of wire-bonding couplings in the package. This LNA is preceded by a five coarse steps (about 11?dB each) digitally-programmable attenuator based on a hybrid T and R-2R network. Together with the LNA, more than 50?dB of gain dynamic range is achieved. For high attenuation steps, input IP₃ of more than +18?dBm is reached.     

Starting phenomenon in negative resistance FET oscillators

The letter provides a study and an explanation of the starting phenomenon in an FET oscillator. It has been shown that the behaviour of the negative resistance with the amplitude of the RF signal leads to a lag effect in the response of the oscillator. This effect is due to the nonlinearity of the transconductance of the active device. Simulations have been made using accurate large signal models included in a time domain analysis software package     

A new full-wave hybrid differential-integral approach for the investigation of multilayer structures including nonuniformly doped diffusions

A novel hybrid differential-integral approach, based on the transverse wave formulation (TWF) is presented for full-wave investigation of multilayer structures including inhomogeneous layer stacks with arbitrary doping profiles. In combining both the benefits of spatial and spectral resolutions, the TWF offers a natural framework for the implementation of multiresolution and multiscale approaches from physical considerations. The possibility of separating the transverse TE and TM components of the TWF solution is discussed. Original isolation structures based on the oxide deep-trenches technique are proposed and demonstrate significant isolation capability in the context of RF integrated-circuit applications.     

Monolithic millimetre-wave amplifiers

Ultra-wideband monolithic HEMT amplifiers have been designed and fabricated using MOCVD heterostructures. It has been shown that by taking into account the multiple reflections at the gate load, a very flat gain can be achieved and the sensitivity of the amplifier to the load resistances can be considerably reduced. By suitable design, the frequency bandwidth of the amplifier can be increased above the cutoff frequency of the active devices. In particular, it is shown that the cascode configuration reduces the coupling between gate and drain lines and increases the gain-bandwidth product, but can generate oscillations. To verify their design approach, the authors present the results obtained on 2-42 GHz monolithic amplifiers using 0.5 mu m HEMTs.<>