SiGe HBT Power Amplifier Research Articles

Performance Limits, Design and Implementation of mm-Wave SiGe HBT Class-E and Stacked Class-E Power Amplifiers

<?Pub Dtl=""?> Design equations and performance limits of Class-E power amplifiers at mm-waves, including the limitations imposed by active and passive devices in a given technology, are presented in this paper. A beyond nominal breakdown voltage Class-E design methodology for SiGe HBT power amplifiers is proposed to generate high output power while maintaining high Class-E efficiency. A mm-wave SiGe stacked Class-E architecture is also introduced to increase the overall voltage swing, with each series stacked device operating in the beyond nominal breakdown mode. The mm-wave beyond <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$BV_{\rm CEO}$</tex></formula> operation of SiGe HBTs has been demonstrated experimentally in an integrated 45 GHz Class-E power amplifier fabricated in a 0.13 µm SiGe BiCMOS process with 20 dBm measured output power at 31.5% peak power-added efficiency (PAE). The series stacking of mm-wave Class-E power amplifier concept is also verified by fabricating double-stacked and triple-stacked SiGe HBT power amplifiers in 0.13 µm SiGe BiCMOS process which demonstrate a measured output power of 23.4 dBm at 41 GHz with peak PAE of 34.9%. High power, highly efficient, switching power amplifier unit cells presented in this paper can facilitate realization of efficient Watt-level mm-wave digital polar transmitters.

A SiGe RF Power Amplifier for TD-SCDMA Application

A SiGe HBT power amplifier for Time Division Synchronous Code-Division Multiple-Access (TD-SCDMA) application with a single positive 3.3V supply has been demonstrated in this paper by adopting a newly proposed usage of the bonding wire. Though the emitter bonding wire may decrease the power gain, it can also decrease the effect of the knee voltage, thus increase the efficiency of the power amplifier. The post-simulation result shows that it can exhibit a linear gain of 29dB, output power of 30dBm, power-added efficiency of 38.49%, and -43dBc suppression at the second harmonic for TD-SCDMA application.

A 2.4-GHz SiGe HBT power amplifier with bias current controlling circuit

A 2.4-GHz SiGe HBT power amplifier (PA) with a novel bias current controlling circuit has been realized in IBM 0.35-μm SiGe BiCMOS technology, BiCMOS5PAe. The bias circuit switches the quiescent current to make the PA operate in a high or low power mode. Under a single supply voltage of +3.5 V, the two-stage mode-switchable power amplifier provides a PAE improvement up to 56.7% and 19.2% at an output power of 0 and 20 dBm, respectively, with a reduced quiescent current in the low power mode as compared to only operating the PA in the high power mode. The die size is only 1.32 × 1.37 mm2.

Concurrent dual-band SiGe HBT power amplifier for Wireless applications

This paper presents an investigation of a concurrent low-cost dual-band power amplifier (PA) fabricated in SiGe technology, able to simultaneously operate at two frequencies of 2.45 and 3.5-GHz, including an evaluation of its system level performance potentiality. Taking into account the technology novelty and the lack of device characterization and modeling, a hybrid (MIC) approach has been adopted both for a fast prototyping of the PA and for the evaluation of the device potentiality based on an extensive linear and nonlinear characterization. The comparison of PA performance in single-band or concurrent mode operation will be presented. In particular, the measured PA prototype shows an output power of 17.2 and 17-dBm at a 1-dB compression point, at 2.45 and 3.5-GHz, respectively, for CW single-mode operation, with a power added efficiency around 20%. System-level analysis predicts that, when the PA is operated under the 20-MHz Orthogonal Frequency-Division Multiplexing (OFDM) concurrent signals, the maximum output power levels to maintain the Error Vector Magnitude (EVM) within 5% are 11 and 3.5-dBm at 2.45 and 3.5-GHz, respectively. Moreover, new concepts and possible new system architectures for the development of the next generation of the multi-band transceiver front-end will be provided with an extensive system-level evaluation of the amplifier.

Compact Modeling of Mutual Thermal Coupling for the Optimal Design of SiGe HBT Power Amplifiers

Most bipolar-transistor compact models incorporate some level of self-heating capability in order to determine the impact of thermal effects on circuit performance. Techniques for predicting mutual-thermal-coupling effects, however, are not readily available within most commercial CAD platforms. Presented in this brief is a technique which allows for the easy modification of design-kit-supplied models to predict and optimize mutual thermal coupling using commonly available CAD tools such as <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Cadence</i> and <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Spectre</i> .

A Monolithic High-Efficiency 2.4-GHz 20-dBm SiGe BiCMOS Envelope-Tracking OFDM Power Amplifier

A monolithic SiGe BiCMOS envelope-tracking power amplifier (PA) is demonstrated for 802.11g OFDM applications at 2.4 GHz. The 4-mm2 die includes a high-efficiency high-precision envelope amplifier and a two-stage SiGe HBT PA for RF amplification. Off-chip digital predistortion is employed to improve EVM performance. The two-stage amplifier exhibits 12-dB gain, <5% EVM, 20-dBm OFDM output power, and an overall efficiency (including the envelope amplifier) of 28%.

RF Characterization of SiGe HBT Power Amplifiers Under Load Mismatch

We present the RF characterization of silicon-germanium heterojunction bipolar transistor (SiGe HBT) power amplifiers (PA) under load mismatched conditions. Experimental results demonstrate a strong dependence of a PA's RF performance on the phase of mismatched antenna loads. For a load mismatch of voltage standing-wave ratio (VSWR) of 10:1, the 1-dB compressed RF output power (P1 dB), transducer gain (GT), output third-order intercept point, and power-added efficiency differ by 7.5 dBm, 8.1 dB, 8.3 dBm, and 15%, respectively, between the optimal and worst phase conditions, for an SiGe HBT PA biased at VCC=3.3 V, collector current ICE =400 mA, and frequency of 1.88 GHz. At the optimal phase condition up to VSWR of 10:1, the SiGe HBT PA maintains its linearity, RF output power, gain, and efficiency close to that at a VSWR of 1:1. At all the nonoptimal phases, the deterioration in the RF performance increases with the magnitude of load mismatches. The nonlinear characteristic of a PA under load mismatches is due to amplitude and phase-distortion mechanisms

A novel diode linearizer for SiGe HBT power amplifier

In this paper, a novel diode linearizer to keep the base voltage of SiGe HBT power amplifier (PA) constant in the large-signal region is introduced. The results show that the output P1dB, and power-added efficiency (PAE) are improved by 4.9 dBm and 22.8%, respectively. At an input power of 20 dBm, the gain compression and phase distortion of the linearized PA is 2.1 dB and 1.1°, respectively, compared with 5.0 dB and 20.4° for the conventional PA. Also, the improved ACPR is given.© 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1535–1537, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21681

A high average-efficiency SiGe HBT power amplifier for WCDMA handset applications

The linearity of a silicon-germanium (SiGe) HBT power amplifier (PA) is analyzed with the help of a power-dependent coefficient Volterra technique. The effect of emitter inductance is included and the dominant sources of nonlinearity are identified. A dynamic current biasing technique is developed to improve the average power efficiency for wide-band code-division multiple-access (WCDMA) PAs. The average power efficiency is improved by more than a factor of two compared to a typical class-AB operation, while the power gain keeps roughly constant. The measured adjacent channel power ratio with 5and 10-MHz offsets at 23.9-dBm average channel output power are -33 and -58.8 dBc, respectively, and satisfies the Third-generation partnership project WCDMA specifications. The output power at the 1-dB compression point is 25.9 dBm