Lawrence E. Larson

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Efficiency and linearity of the microwave power amplifier are critical elements for mobile communication systems. This paper discusses improvements in system efficiency that are obtainable when a dc–dc converter is used to convert available battery voltage to an optimal supply voltage for the output RF amplifier. A boost dc–dc converter with an operating(More)
An extension of the Doherty amplifier, which maintains high efficiency over a wide range of output power ( 6 dB), is presented in this paper. This extended Doherty amplifier is demonstrated experimentally with InGaP/GaAs heterojunction bipolar transistors at 950 MHz. Power-added efficiency (PAE) of 46% is measured at 1dB of 27.5 dBm and 45% is measured at 9(More)
A nonlinear capacitance-compensation technique is developed to help improve the linearity of CMOS class-AB power amplifiers. The method involves placing a PMOS device alongside the NMOS device that works as the amplifying unit, such that the overall capacitance seen at the amplifier input is a constant, thus improving linearity. The technique is developed(More)
A FET linearization technique based on optimum gate biasing is investigated at RF. A novel bias circuit is proposed to generate the gate voltage for zero 3rd-order nonlinearity of the FET transconductance. The measured data show that a peak in IIP3 occurs at a gate voltage slightly different from the one predicted by the dc theory. The origins of this(More)
A CMOS mixer whose linearity is maintained for a wide frequency range is presented. Transconductance (<i>Gm</i>) boosting methods, such as input cross-coupling, current reuse complementary input, and back gate connection, are used to improve overall gain and noise performance. A source-degenerated passive mixer is used to improve noise figure (NF) by(More)
Envelope Tracking (ET) is an efficiency enhancement technique where the power supply of a linear RF power amplifier (PA) follows the envelope of the RF signal. It is specifically effective for the high peak-to-average power ratio (PAPR) signals of modern communication systems. But due to envelope bandwidth expansion and watt-level power requirements, the(More)
Implemented in a 0.25m SiGe BiCMOS process, a highly integrated low-power transmitter IC (TxIC) is developed for wideband code-division multiple-access handset applications. Based on a digital-IF heterodyne architecture, it eliminates the external IF surface acoustic wave filter by adopting a meticulous frequency plan and a special-purpose second-order-hold(More)
Electrical balance between the antenna and the balance network impedances is crucial for achieving high isolation in a hybrid transformer duplexer. In this paper an auto calibration loop for tuning a novel integrated balance network to track the antenna impedance variations is introduced. It achieves an isolation of more than 50 dB in the transmit and(More)
A wideband sub-harmonic mixer/direct-conversion downconverter is implemented in a Si/SiGe HBT technology, with improved rejection of the local oscillator (LO), high input intercept point, and low current requirements. The circuit utilizes a combination of phase shifters operating at 45 and 90 to achieve better than 33-dB input-referred rejection of the LO.(More)