Won Ko

Design and Analysis of a Cascode Bipolar Low-Noise Amplifier With Capacitive Shunt Feedback Under Power-Constraint

A cascode bipolar low-noise amplifier (LNA) with capacitive shunt feedback has been developed to present a solution for simultaneous noise and power match when the real part of the optimum source impedance is not 50 Ω in order to keep high current density under power constraint. The proposed LNA also has the capability for the simultaneous improvement of noise figure (NF) and linearity. In addition, we analyzed and verified that the second-order interaction, which affects the third-order nonlinearity, becomes less sensitive to the low-frequency input termination at higher bias currents. The possibility of removing the low-frequency LC trap is investigated based on this analysis. We also show that LNAs with smaller base and/or smaller emitter resistances require lower source impedance at low frequencies to improve linearity by the same amount. Finally, prudent layouts for improving the performance of the LNA are considered. Eleven design examples of the proposed LNA, which individually operate at 880, 1575, or 1960 MHz, are fabricated in a low-cost 0.35- μm SiGe BiCMOS process to verify the design and analysis experimentally. The fabricated LNAs have excellent performances, especially in NF. For example, the 880-MHz LNA has an NF of 0.9 dB, a power gain of 16 dB, and an IIP3 of +14 dBm with current consumption of 11 mA from a 2.8-V power supply.

Design and Analysis of an Ultra-Wideband Automatic Self-Calibrating Upconverter in 65-nm CMOS

In this paper, an ultra-wideband (UWB) upconverter is proposed that has automatic self-calibrating circuits for the in-phase/quadrature mismatch correction and the local (LO) leakage suppression. The proposed self-calibrating circuits have been devised to have UWB functionality without help of the baseband processor. In addition, calibrating circuits do not need any additional analog-to-digital converter or sample-and-hold capacitors that are used to store and update the minimum power because the proposed calibrators find the solution from informations in current state. To verify the performance, the upconverter was applied to an UWB transmitter (Tx), operating from 3.1 to 4.8 GHz and from 6.3 to 9 GHz in 65-nm CMOS. The measured data shows UWB performance for the sideband rejection up to 9 GHz and the LO leakage suppression up to 5 GHz, respectively. The automatically calibrated Tx has error vector magnitude of lower than -20 dB, output 1-dB compression point of -6 dBm, LO leakage of lower than -43 dBm, and sideband suppression ratio of higher than 45 dBc with current consumption of 175 mA from a 1.2-V power supply for all supporting bands and time frequency codes defined in WiMedia UWB specifications.

The Effects of Coating Treatments on Enteric Coating of the Soft Capsules Containing Omega-3 Fatty Acids

This article presents an evaluation of the effects of coating conditions on the enteric coating quality of soft gelatin capsules containing Omega-3 fatty acids. Three conditions were controlled: concentration of hydroxypropyl methylcellulose phthalate (6, 8, and 10 wt% in solution), temperature of the inlet air (32, 35, and 38 o C), and the coating solution feed rate (7.5, 11.25, and 15.0 g/min). The transparency of the enteric coated soft gelatin capsules was evaluated by measuring the degree of whiteness of the surface using a spectrophotometer. Results showed that the most important parameter in the enteric coating process was the coating solution feed rate. As the coating solution feed rate decreased and inlet air temperature increased, the degree of whiteness of coating surfaces decreased. We also evaluated the disintegration properties of the enteric coated capsules in accordance with the Korea Health Functional Food Code.

Dissolution profile analysis of hydroxypropyl methylcellulose-based vitamin c tablets

The objective of this study was to develop oral matrix tablets for the sustained release of vitamin C. In this study hydroxypropyl methylcellulose (HPMC) has been utilized as an excipient, as it is one of the most widely used polymers, for use during long periods of time in formations. The vitamin C tablet formulation depends on the molecular weight and concentration of sustained-delivery in HPMC. Anti-oxidants have been added as a dissolution medium in order to prevent vitamin C degradation in water. The dissolution test was carried out in a distilled water medium, and the release model equation was applied to analyze the vitamin C release pattern. The results demonstrated that the release and lasting power of vitamin C tablets, containing HPMC, lasted for more than 12 h.

An Ultra-wideband transmitter with automatic self-calibration of sideband rejection up to 9 GHz in 65nm CMOS

An Ultra-wideband (UWB) transmitter is proposed that can correct phase errors in quadrature local (LO) signals automatically without help of baseband processor (BBP), operating from 3 to 9 GHz in 65 nm CMOS. The measured tuning range for sideband rejection is 32.7 dB at 7.7 GHz and 13.6 dB at 8.7 GHz. The measured EVM is lower than −20 dB for all supporting bands and TFCs (Time frequency codes) that are prescribed by WiMedia alliance. The power consumption of the transmitter including LO path and PLLs is 210 mW from a 1.2 V supply.

A 65nm CMOS low-noise three band group WiMedia UWB receiver

A low-noise and high-gain ultra wideband (UWB) receiver was developed using a 65nm CMOS technology and a wafer-level fabricated package. In order to enhance the gain and noise figure over a wide frequency band, the resistive feedback amplifier and two cascode stages with the inductive load resonating at three different frequencies are employed. The fabricated UWB receiver showed a high gain of 72.6 dB ± 0.7 dB overall operating frequency range, and an average noise figure of 4.1 dB in 3168 to 4752 MHz, 4.3 dB in 6366 to 7920 MHz and 5.1 dB in 7392 to 8976 MHz frequency band, respectively. The noise figure at high frequency edge is lower than 6 dB. The measured sensitivities in three band groups meet all WiMedia PHY specifications.

A WiMedia UWB transmitter up to 9GHz in 65nm CMOS and Wafer-Level Fabricated Package

A 3.1–4.7GHz and 6.3–9GHz RF transmitter fabricated in a 65nm CMOS technology and packaged with a Wafer-level Fabricated Package (WFP) is presented. For high frequency and wideband performances, all the effects of package are considered and loopback paths with a power detector are implemented. A new structure of T/R switch is devised for the low noise performance of Rx and the high linearity of Tx. With these circuits, the transmitter features high linearity, low power consumption and small chip area meeting all the WiMedia PHY spec.

A single-chip CDMA-2000 zero-IF transceiver for band-class 4 with GPS support

A single-chip cdma-2000 zero-IF transceiver has been successfully developed for band-class 4 (Korean-PCS band) with an additional GPS signal receiving functionality. The receiver showed excellent noise and linearity performance (full- path NF=2dB, IIP3=-6dBm) with very low phase-noise VCO (- 132dBc/Hz@1.25MHz/fOSC=3.71G). The Tx-Rx isolation turned out to be good enough for the sensitivity and single-tone desensitization requirement of the CDMA-2000 system. The IC was implemented on a 0.35mum SiGe BiCMOS technology.