Sung-Gi Yang

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.

A dual-b and RF front-end of direct conversion receiver for wireless CDMA cellular phones with GPS capability

A highly integrated direct conversion receiver for cellular code division multiple access (CDMA) and GPS applications is successfully developed using a 0.5-/spl mu/m SiGe BiCMOS technology. The receiver consists of two low-noise amplifiers (LNAs), a dual-band mixer, two voltage-controlled oscillators (VCOs), a local-oscillator signal generation block, and channel filters. The CDMA LNA achieves a noise figure of 1.3 dB, an input-referred third-order intercept point (IIP3) of 10.9 dBm, and a gain of 15.3 dB with a current consumption of 9.8 mA in the high-gain mode. The mixer for the CDMA mode achieves an uncalibrated input-referred second-order intercept point of 53.7 dBm, an IIP3 of 6.4 dBm, a noise figure of 7.2 dB and a voltage gain of 37.2 dB. The phase noise of the CDMA VCO is approximately -133 dBc/Hz at a 900-kHz offset from a 1.762-GHz operating frequency. It exceeds all the CDMA requirements when tested on a handset.

Design and analysis of a high-performance cascode bipolar low noise amplifier with shunt feedback capacitor

In this paper, a cascode bipolar low noise amplifier (LNA) employing a shunt feedback capacitor is presented, for which the linearity and the noise figure (NF) can be optimized by reducing the transistor size and degeneration inductance. We also show that the second-order interaction, which affects the third-order nonlinearity, becomes insensitive to low-frequency input termination as the DC current increases. Finally, the method of removing the low-frequency trap is presented. The fabricated LNA in 0.35-mum SiGe BiCMOS process showed NF of 0.9 dB with 16-dB power gain and IIP3 of +11 dBm with current consumption of 10 mA from 2.8-V power supply at 900 MHz. The demonstrated LNA satisfies stringent sensitivity and linearity requirement of code-division multiple-access (CDMA) applications quite well.

A High Gain-Bandwidth Baseband GaAs P-HEMT Matrix Distributed Amplifier IC with a Shifted Second Tier Structure

A new matrix distributed amplifier has been proposed, in which the second tier has been shifted to the output load. It was intended to increase the amplifications from the later shunt arms of the center line whose voltages are always larger than that of the earlier ones, so that the overall gain could be improved without compromising with the bandwidth. In addition, a new bias scheme was also employed that extended the gain down to the extremely low frequency and resulted in a first baseband matrix distributed amplifier. The proposed design has been verified by using a 0.25¿m self-aligned gate GaAs P-HEMT coplanar IC process, and yielded a gain of 18.5dB from 0-30 GHz, which was 3dB higher than that of the conventional design.

IP2 calibrator using common mode feedback circuitry

An IP2 calibration technique is developed using the common mode feedback circuitry in a direct-conversion receiver for wireless CDMA/PCS/GPS/FM applications. The IP2 calibrator is capable of providing a different CMFB gain to tune its common mode output impedance for each of the positive and negative mixer outputs. The method performs a 20-dB improvement in IIP2. The CDMA mixer achieves an uncalibrated IIP2 of 44 dBm, an IIP3 of 4 dBm, a noise figure of 6.5 dB and a voltage gain of 42.2 dB. The receiver RFIC is implemented in a 0.5 /spl mu/m SiGe BiCMOS process, and it operates from a 2.7 to 3.1 V single power supply. It exceeds all CDMA requirements when tested individually or on a handset.

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.

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 compact and wideband GaAs P-HEMT distributed amplifier IC based on a micro-machined CPW

This paper presents a new GaAs P-HEMT distributed amplifier IC that employs a micro-machined, grooved-CPW. By removing the substrate between the signal and ground metal, the grooved-CPW has small effective dielectric constant (/spl epsi//sub r,eff/) and becomes a highly inductive line. When the grooved-CPW is used in the distributed amplifier, the f/sub 3dB/ and the chip size have been improved by about 20%. The fabricated GaAs P-HEMT distributed amplifier IC has a gain of 10 dB with f/sub 3dB/>50 GHz.

A CMOS VCO with Optimized Tune Branches for Zero-IF CDMA Cellular Application in a 0.5μm BiCMOS process

A fully integrated, very-low phase-noise CMOS voltage controlled oscillator (VCO) has been implemented for zero-IF CDMA cellular receiver (Rx) using CMOS transistors in a 0.5mum SiGe BiCMOS process technology. To optimize the phase noise performance, the VCO used the proposed coarse and fine tune branch which employed high-Q accumulation-mode MOS (AMOS) varactors. The measured phase noise is below -133dBc/Hz at 900kHz offset frequency from a 1.762GHz carrier, which yields enough margin for the IS-98 single-tone test requirement. The integrated CDMA cellular Rx including this Rx VCO shows more than 2.5dB single-tone performance margin

New Self-align Method for Fabrication of 980 nm Ridge Waveguide Laser Diodes

A novel self-align method has been developed for the fabrication of 980 nm ridge waveguide laser diodes. It utilizes the facts that (1) the thickness of photoresist on the ridge top is substantially less than that in its vicinity and (2) their respective exposure times differ accordingly. Except for replacing the second photolithographic step with a simple flood-exposure, the fabrication procedure is identical to that for conventional ridge waveguide laser diodes. No additional materials or processing steps are required. As a result, the laser fabrication is significantly simplified with excellent reproducibility.