Analysis and Design of RF Integrated Circuits and Systems

Wearable systems are expected to contribute for improving traditional biopotential signals monitoring devices due to higher freedom and unobtrusiveness provided to the wearer. Textile electrodes present advantages compared with the conventional Ag/AgCl electrodes for the capturing of biopotentials, namely in terms of skin irritation due to the hydrogel and the need of a technician to place the electrodes on the correct positions. Due to the lack of hydrogel, textile electrodes present different electrical contact characteristics. The skinelectrode impedance is an important feature since it affects the captured signal quality. Although a low impedance is desired, a comfortable wearable system should not require the electrodes to be covered by the hydrogel or be moistened. A forearm sleeve provided with textile electrodes was used to study the electrode-skin impedance and the signal-to-noise ratio (SNR) of surface electromyographic (EMG) signals on a long-term use basis. The sleeve can be adjusted for different levels of tightening to control the pressure applied on the electrodes. The obtained results provide valuable information on the pressure that the textile garments of a sleeve or vest should apply on the recording electrodes, in order to assure a good electrical and mechanical contact between the electrodes and the skin and decrease the noise due to motion. It was observed that the electrode-skin impedance measurement alone is not sufficient to establish a relation with the SNR. The extraction of parameters from an electrical equivalent model of the electrode-skin interface allows to determine a relation with the model parameters and the SNR. The evaluation of these parameters during long-term monitoring will allow assessing the quality of biopotential measurements in textile electrodes.

This paper represents a new enhanced Colpitts oscillator, which is designed based on gm-boosting of a conventional Colpitts oscillator. The proposed topology increases the negative
resistant and enhances the start-up dificulty of the conventional Colpitts oscillator. This enables the Colpitts oscillator to operate in low-power consumption. Moreover, the differential
and balanced structure helps limit even-order harmonics and degrades the common mode noise effects in output. The proposed circuit is designed using 0.18 u
m technology and is simulated under 1.8V supply voltage in advanced design system (ADS). Simulations show the output phase noise of
140 dBc/Hz at 1MHz offset frequency when the operating frequency is 1 GHz.

Some sensor systems are characterized by multiple simultaneous aperiodic emissions, with low signal-to-noise ratio and asynchronous detection. In these systems, complementary sets of sequences can be used to encode emissions, due to their suitable auto-correlation and cross-correlation properties. The transmission of a complementary set can be accomplished by interleaving the sequences of the set, generating a macro-sequence which is easily transmitted by a BPSK modulation. The detection of the macrosequence can be performed by means of efficient correlation algorithms with a notably decreased computational load and hardware complexity. This work presents a new hardware design in configurable logic of an efficient correlator for macrosequences generated from complementary sets of sequences. A generic implementation has been achieved, so the configuration can be changed according to the requirements of the application. The developed correlator has been tested in an ultrasonic pulse compression system in which real-time is needed. However, it is applicable in any multi-sensor or communication system where the goal is to make simultaneous emissions from different independent sources, minimizing mutual interference.

An operational transconductance amplifier (OTA) using dynamic threshold MOS (DTMOS) and hybrid compensation technique is presented in this paper. The proposed topology is based on a bulk and gate driven input differential pair. Two separate capacitors are employed for the OTA compensation where one of them is used in a signal path and the other one in a non-signal path. The circuit is designed in the 0.18 μm CMOS TSMC technology. The proposed design technique shows remarkable enhancement in unity gain-bandwidth and also in DC gain compared to the bulk driven input differential pair OTAs. The Hspice simulation results show that the amplifier has a 92 dB open-loop DC gain and a unity gainbandwidth of 135 kHz while operating at 0.4 V supply voltage. The total power consumption is as low as 386 nW which makes it suitable for low-power bio-medical and bio-implantable applications.

Some sensor systems are characterized by multiple simultaneous aperiodic emissions, with low signal-to-noise ratio and asynchronous detection. In these systems, complementary sets of sequences can be used to encode emissions, due to their suitable auto-correlation and cross-correlation properties. The transmission of a complementary set can be accomplished by interleaving the sequences of the set, generating a macro-sequence which is easily transmitted by a BPSK modulation. The detection of the macrosequence can be performed by means of efficient correlation algorithms with a notably decreased computational load and hardware complexity. This work presents a new hardware design in configurable logic of an efficient correlator for macrosequences generated from complementary sets of sequences. A generic implementation has been achieved, so the configuration can be changed according to the requirements of the application. The developed correlator has been tested in an ultrasonic pulse compression system in which real-time is needed. However, it is applicable in any multi-sensor or communication system where the goal is to make simultaneous emissions from different independent sources, minimizing mutual interference.

Wearable systems are expected to contribute for improving traditional biopotential signals monitoring devices due to higher freedom and unobtrusiveness provided to the wearer. Textile electrodes present advantages compared with the conventional Ag/AgCl electrodes for the capturing of biopotentials, namely in terms of skin irritation due to the hydrogel and the need of a technician to place the electrodes on the correct positions. Due to the lack of hydrogel, textile electrodes present different electrical contact characteristics. The skinelectrode impedance is an important feature since it affects the captured signal quality. Although a low impedance is desired, a comfortable wearable system should not require the electrodes to be covered by the hydrogel or be moistened. A forearm sleeve provided with textile electrodes was used to study the electrode-skin impedance and the signal-to-noise ratio (SNR) of surface electromyographic (EMG) signals on a long-term use basis. The sleeve can be adjusted for different levels of tightening to control the pressure applied on the electrodes. The obtained results provide valuable information on the pressure that the textile garments of a sleeve or vest should apply on the recording electrodes, in order to assure a good electrical and mechanical contact between the electrodes and the skin and decrease the noise due to motion. It was observed that the electrode-skin impedance measurement alone is not sufficient to establish a relation with the SNR. The extraction of parameters from an electrical equivalent model of the electrode-skin interface allows to determine a relation with the model parameters and the SNR. The evaluation of these parameters during long-term monitoring will allow assessing the quality of biopotential measurements in textile electrodes.

A fully differential ultra low-voltage, ultra low-power down-conversion mixer is presented in this paper. The mixer is designed using four-terminal MOS transistors. The radio-frequency (RF) and local-oscillator signals are applied to the gate and bulk of the devices, respectively. The proposed circuit is designed and simulated in the TSMC 0.18_μm CMOS process, with a 1.9GHz RF signal; the simulation results show that the proposed mixer has a conversion gain of 8dB, IIP3 of -10.6dBm and SSB noise figure of 12.7dB. The total power consumption in the 0.5 V supply voltage is 1.32mW.

The Fast Field Cycling (FFC) Nuclear Magnetic Resonance (NMR) equipment has been mainly developed by engineers with a strong background in power electronics, control and physics. This technique has been widely used by physicists, chemists, biologists, pharmacists and food analysts. During the last decades, the development of this type of apparatus has been taking advantage of the power semiconductors, topologies of the power electronic converters, control techniques, computational tools and materials, among other aspects. In this paper, teaching aspects of using this type of equipment and technique in courses of physics and electrical engineering is described.

This paper represents a new enhanced Colpitts oscillator, which is designed based on gm-boosting of a conventional Colpitts oscillator. The proposed topology increases the negative resistant and enhances the start-up difficulty of the conventional Colpitts oscillator. This enables the Colpitts oscillator to operate in low-power consumption. Moreover, the differential and balanced structure helps limit even-order harmonics and degrades the common mode noise effects in output. The proposed circuit is designed using 0.18 μm technology and is simulated under 1.8 V supply voltage in advanced design system (ADS). Simulations show the output phase noise of -140 dBc/Hz at 1 MHz offset frequency when the operating frequency is 1 GHz.

CO-design methodologies have arisen for supporting the development of digital systems composed of mixed hardware/software. Partitioning is performed by codesign tools for splitting the funcionality of the original system among components. In this paper, a partitioning approach based on a Petri net intermediate format is proposed. The new model will substitute the one currently adopted in PISH co-design system. The main advantages of such model are having more precise metrics and becoming independent of the specification language.

... Springer Verlag, 1995. [7] ACV de Melo and H. Barringer. ... [12] MJ Gordon. Why higher–order logic is a good formalism for specifying and verifying hardware. In GJ Milne and PASubrahmanyam, editors, Formal Aspects of VLSI De-sign. North–Holland, 1986. ...

CO-design methodologies have arisen for supporting the development of digital systems composed of mixed hardware/software. Partitioning is performed by codesign tools for splitting the funcionality of the original system among components. In this paper, a partitioning approach based on a Petri net intermediate format is proposed. The new model will substitute the one currently adopted in PISH co-design system. The main advantages of such model are having more precise metrics and becoming independent of the specification language.

An operational transconductance amplifier (OTA) using dynamic threshold MOS (DTMOS) and hybrid compensation technique is presented in this paper. The proposed topology is based on a bulk and gate driven input differential pair. Two separate capacitors are employed for the OTA compensation where one of them is used in a signal path and the other one in a non-signal path. The circuit is designed in the 0.18µm CMOS TSMC technology. The proposed design technique shows remarkable enhancement in unity gain-bandwidth and also in DC gain compared to the bulk driven input differential pair OTAs. The Hspice simulation results show that the amplifier has a 92dB open-loop DC gain and a unity gain-bandwidth of 135kHz while operating at 0.4V supply voltage. The total power consumption is as low as 386nW which makes it suitable for low-power bio-medical and bio-implantable applications.

A highly linear, low voltage, low power, low noise amplifier (LNA) using a novel nonlinearity cancellation technique is presented in this paper. Parallel Inductor (PI) matching is used to increase LNA gain by 3dB at the desired frequency. The linear LNA was designed and simulated in a TSMC 0.18μm CMOS process at 5GHz frequency. By employing the proposed technique, the IIP 3 is improved by 12dB in contrast to the conventional folded cascode LNA, reaching -1dBm without having any significant effect on the other LNA parameters such as gain, NF and also power consumption. The proposed LNA also delivers a voltage gain (S 21 ) of 12.25dB with a noise figure of 3.5dB, while consuming only 1.28mW of DC power with a low supply voltage of 0.6V.