Realization of a single-chip, SiGe:C-based power amplifier for multi-band WiMAX applications

A fully-integrated Multi-Band PA using 0.25 μm SiGe:C process with an output power of above 25 dBm is presented. The behaviour of the amplifier has been optimized for multi-band operation covering, 2.4 GHz, 3.6 GHz and 5.4 GHz (UWB-WiMAX) frequency bands for higher 1-dB compression point and efficiency. Multi-band operation is achieved using multi-stage topology. Parasitic components of active devices are also used as matching components, in turn decreasing the number of matching component. Measurement results of the PA provided the following performance parameters: 1-dB compression point of 20.5 dBm, gain value of 23 dB and efficiency value of %7 operation for the 2.4 GHz band; 1-dB compression point of 25.5 dBm, gain value of 31.5 dB and efficiency value of %17.5 for the 3.6 GHz band; 1-dB compression point of 22.4 dBm, gain value of 24.4 dB and efficiency value of %9.5 for the 5.4 GHz band. Measurement results show that using multi-stage topologies and implementing each parasitic as part of the matching network component has provided a wider-band operation with higher output power levels, above 25 dBm, with SiGe:C process

A 4.5-5.8 GHz Differential LC VCO using 0.35 m SiGe BiCMOS Technology

In this paper, design and realization of a 4.5-5.8 GHz, Gm LC voltage controlled oscillator (VCO) for IEEE 802.11a standard is presented. The circuit is implemented with 0.35´m SiGe BiCMOS process that includes high-speed SiGe Heterojunction Bipolar Transistors (HBTs). A linear, 1300 MHz tuning range is measured with accumulation-mode varactors. Fundamental frequency output power changes between -1.6 dBm and 0.9 dBm, depending on the tuning voltage. The circuit draws 17 mA from 3.3 V supply, including buffer circuits leading to a total power dissipation of 56 mW. Post-layout phase noise is simulated -110.7 dBc/Hz at 1MHz offset from 5.8 GHz carrier frequency and -113.4 dBc/Hz from 4.5 GHz carrier frequency. Phase noise measurements will be updated in the final manuscript. The circuit occupies an area of 0.6 mm2 on Si substrate including RF and DC pads

A fully integrated multiband frequency synthesizer for WLAN and WiMAX applications

This paper presents a fractional N frequency synthesizer which covers WLAN and WiMAX frequencies on a single chip. The synthesizer is fully integrated in 0.35μm BiCMOS AMS technology except crystal oscillator. The synthesizer operates at four frequency bands (3.101-3.352GHz, 3.379-3.727GHz, 3.7-4.2GHz, 4.5-5.321GHz) to provide the specifications of 802.16 and 802.11 a/b/g/y. A single on-chip LC - Gm based VCO is implemented as the core of this synthesizer. Different frequency bands are selected via capacitance switching and fine tuning is done using varactor for each of these bands. A bandgap reference circuit is implemented inside of this charge pump block to generate temperature and power supply independent reference currents. Simulated settling time is around 10μsec. Total power consumption is measured to be 118.6mW without pad driving output buffers from a 3.3V supply. The phase noise of the oscillator is lower than -116.4dbc/Hz for all bands. The circuit occupies 2.784 mm2 on Si substrate, including DC, Digital and RF pads

Design of a 4.2-5.4 GHz Differential LC VCO using 0.35 m SiGe BiCMOS Technology

In this paper, a 4.2-5.4 GHz, Gm LC voltage controlled oscillator (VCO) for IEEE 802.11a standard is presented. The circuit is designed with AMS 0.35´m SiGe BiCMOS process that includes high-speed SiGe Heterojunction Bipolar Transistors (HBTs). Phase noise is -110.7 dBc/Hz at 1MHz offset from 5.4 GHz carrier frequency and -113.5 dBc/Hz from 4.2 GHz carrier frequency. A linear, 1200 MHz tuning range is obtained utilizing accumulation-mode varactors. Phase noise is relatively low due to taking the advantage of differential tuning concept. Output power of the fundamental frequency changes between 4.8 dBm and 5.5 dBm depending on the tuning voltage. The circuit draws 2 mA without buffers and 14.5 mA from 2.5 V supply including buffer circuits leading to a total power dissipation of 36.25 mW. The circuit occupies an area of 0.6 mm2 on Si substrate including RF and DC pads

Fully integrated low-power SiGe power amplifier for biomedical applications

A full-integrated very low-power SiGe power amplifier (PA) is realised using the innovations for high performance, 0.25 mu m SiGe process. The behaviour of the amplifiers has been optimised for the 2.1-2.4 GHz frequency band for a higher 1 dB compression point and high efficiency at a lower supply voltage. The PA delivers an output power of 3.75 and 1.25 mW for 2 and 1 V, respectively. The PA measurements yielded the following parameters: gain of 13 dB, 1 dB compression point of 5.7 dBm, and power added efficiency of 30% for 2 V supply voltage. The PA circuit can go down to 1 V of supply voltage with a gain of 10 dB, 1 dB compression point of 1 dBm, and power added efficiency of 20%. For both supply voltages, the input and the output of the circuit give good reflection performance. With this performance, the PA circuit may be used for low-power biomedical implanted transceiver systems

A fully integrated low-power SiGe power amplifier for biomedical applications

In this work, a full-integrated very-low power SiGe Power Amplifier (PA) is realized using the IHP (Innovations for High Performance), 0.25μm-SiGe process. The behaviour of the amplifiers has been optimized for the 2.1-2.4 GHz frequency band for a higher 1-dB compression point and high efficiency at a lower supply voltage. The PA delivers an output power of 3.75 mW and 1.25 mW for 2V and 1V, respectively. The PA measurements yielded the following parameters; gain of 13 dB, 1-dB compression point of 5.7 dBm, and Power-Added-Efficiency of 30% for 2V supply voltage. The PA circuit can go down to 1V of supply voltage with a gain of 10 dB, 1-dB compression point of 1 dBm, and Power-Added-Efficiency of 20%. For both supply voltages, the input and the output of the circuit give good reflection performance. With this performance, the PA circuit may be used for low-power biomedical implanted transceiver systems

A Coplanar waveguide on-chip RF choke for WLAN RF circuits

A novel on-chip RF choke at 5 GHz is designed and measured for a class A operating Wireless LAN RF power amplifier (PA). The coplanar waveguide (CPW)-based on-chip RF choke is implemented as an alternative component to inductors provided by the 0.35-m SiGe BiCMOS technology. The CPW RF choke is designed at 5 GHz, and has a length of 1600 m and loaded with a capacitance of 0.95 pF. The measured impedance of the RF choke at 5 GHz is around 104

Design of a tunable multi-band differential LC VCO using 0.35 mu m SiGe BiCMOS technology for multi-standard wireless communication systems

In this paper, an integrated 2.2-5.7GHz multi-band differential LC VCO for multi-standard wireless communication systems was designed utilizing 0.35 mu m SiGe BiCMOS technology. The topology, which combines the switching inductors and capacitors together in the same circuit, is a novel approach for wideband VCOs. Based on the post-layout simulation results, the VCO can be tuned using a DC voltage of 0 to 3.3 V for 5 different frequency bands (2.27-2.51 GHz, 2.48-2.78 GHz, 3.22-3.53 GHz, 3.48-3.91 GHz and 4.528-5.7 GHz) with a maximum bandwidth of 1.36 GHz and a minimum bandwidth of 300 MHz. The designed and simulated VCO can generate a differential output power between 0.992 and -6.087 dBm with an average power consumption of 44.21 mW including the buffers. The average second and third harmonics level were obtained as -37.21 and -47.6 dBm, respectively. The phase noise between -110.45 and -122.5 dBc/Hz, that was simulated at 1 MHz offset, can be obtained through the frequency of interest. Additionally, the figure of merit (FOM), that includes all important parameters such as the phase noise, the power consumption and the ratio of the operating frequency to the offset frequency, is between -176.48 and -181.16 and comparable or better than the ones with the other current VCOs. The main advantage of this study in comparison with the other VCOs, is covering 5 frequency bands starting from 2.27 up to 5.76 GHz without FOM and area abandonment. Output power of the fundamental frequency changes between -6.087 and 0.992 dBm, depending on the bias conditions (operating bands). Based on the post-layout simulation results, the core VCO circuit draws a current between 2.4-6.3 mA and between 11.4 and 15.3 mA with the buffer circuit from 3.3 V supply. The circuit occupies an area of 1.477 mm(2) on Si substrate, including DC, digital and RF pads

Impedance Matching Wilkinson Power Dividers in 0.35μm SiGe BiCMOS Technology

This paper presents two miniature Impedance Matching Wilkinson Power Divider circuits in 0.35μm SiGe BiCMOS technology for on-chip power combining techniques for WLAN applications. The Impedance Matching Wilkinson Power Divider circuits are used as splitter/combiner for a 5.2 GHz fully integrated class-A mode combined power amplifier. The splitter and combiner are designed to match the input and output impedances of the amplifier, respectively, so that no additional impedance matching is needed. Two fabricated impedance matching Wilkinson power divider circuits (splitter and combiner) have insertion losses better than 1.4dB, return losses less than -13dB and port-to-port isolation > 12 dB at 5.2GHz

RISK-TAKING BEHAVIOR IN RECOVERED COVID-19 PATIENTS

Background: The aim of this study is to investigate risk-taking behavior and decision-making processes in recovered COVID- 19 patients. Subjects and methods: Twenty patients recovered from COVID-19 as confirmed by polymerase chain reaction (PCR) tests and twenty-one healthy individuals were recruited. A computerized version of the Iowa Gambling Test (IGT) for measuring risk taking behavior tendencies as a decision-making process and State-Trait Anxiety Inventory (STAI), Beck Depression Inventory (BDI), and WMS-R Digit Span Forward Test (DSFT) for clinical assessments included. The assessments of the recovered patients were applied on the initial phase that the tests of the patients were negative and on the 4-week follow up phase. Results: The results showed that the anxiety scores were significantly higher in the healthy control group than in the group of recovered patients. The IGT-Net 4 scores were significantly and IGT-Net total scores were marginally significantly lower in the group of recovered patients. In other words, recovered patients showed higher risk-taking behavior tendencies. This tendency difference is consistent with the anxiety levels of the groups. These IGT scores showed to be persistent in the 4-week follow up phase. Conclusions: Our findings indicate that recovered patients show higher risk-taking behavior tendencies than healthy controls and this may be the result of overcoming the COVID-19 threat