This article discusses techniques for the cancellation of distortion (linearization) in power amplifiers. Different methods of linearization are introduced and compared. The linearization of solid-state power amplifiers (SSPAs), traveling-wave tube amplifiers (TWTAs) and klystron power amplifiers (KPAs) are considered. Although the focus of this article is on power amplifiers, many of the techniques are applicable to other components such as mixers, low-noise amplifiers, and even photonic components, such as lasers and optical modulators.

Linearization: reducing distortion in power amplifiers

Signals, systems and methods for transmitting and receiving layered modulation for digital signals are presented. A layered signal for transmitting data, comprises a first signal layer including a first carrier and first signal symbols for a first digital signal transmission and a second signal layer including a second carrier and second signal symbols for a second signal, transmission disposed on the first signal layer, wherein the layered signal has the first carrier demodulated and first layer decoded to produce the first signal symbols for a first layer transport, the first signal symbols are remodulated and subtracted from the layered signal to produce the second signal layer, and the second signal layer has the second carrier demodulated and decoded to produce the second signal symbols for a second layer transport.

Layered modulation for digital signals

A broadband power amplifier module for high bit-rate SONET/SDH transmission channels, such as OC-192 and OC-768 applications. The power amplifier module, or also frequently referred to as modulator driver module, comprises amplifiers connected in series to amplify an input signal. A bias tee circuit is incorporated into the power amplifier module by connecting a conical shape inductor between the output stage of the amplifiers and the supply voltage and connecting a pair of blocking capacitors also at the output stage of the amplifiers. The conical shape inductor is adapted to provide high impedance over the entire bandwidth. The capacitors are adapted to provide high self-resonant frequency that is approaching or exceeding the bandwidth frequency. A power detection circuit can also be incorporated into the power amplifier module at the output stage of the amplifiers. The power detection circuit has a voltage divider circuit connected between the output stage and a ground supply. The divider circuit taps off a portion of the energy from the output stage to be measured by a detection diode. A ¼-wave radial matching stub is connected to the detection diode to filter RF energy. Another ¼-wave matching stub is connected to the divider circuit to provide grounding. Capacitors are also connected to the output of the detection diode to filter noise in the detector output voltage over a entire frequency bandwidth.

Ultra-wideband power amplifier module apparatus and method for optical and electronic communications

A method and apparatus for equalizing digital data signals is disclosed. The method comprises the steps of demodulating and decoding an input signal having input data to produce a data output, remodulating the data output to produce a training sequence including an idealized input signal, wherein the training sequence is comprised of adjacent symbols in the input data, and generating equalizer parameters from the training sequence. The apparatus comprises a demodulator (for demodulating an input signal to produce a data output), a modulator communicatively coupled to the demodulator (for remodulating the data output to produce a training sequence including an idealized input signal wherein the training sequence is comprised of adjacent symbols in the input data), and a parameter generation module communicatively coupled to the modulator (for generating equalizer parameters from the training sequence).

Equalizers for layered modulated and other signals

Methods and apparatuses for maximizing power and spectral efficiencies in a wireless communication system are disclosed. The invention is particularly useful for layered modulation applications because power levels for such applications are relatively high. A layered modulation signal comprises an upper and a lower layer signal that interfere with each other within the same frequency band such that the upper layer signal can be demodulated directly from the layered modulation signal, and the lower layer signal can be demodulated after subtracting the first layer signal from the layered modulation signal. The invention applies one or more of the following four signal schemes in a communication signal including varying the symbol rate (rather than the code rate), reducing or eliminating the guard band, reducing excess signal bandwidth and employing layered modulation within the guard band of the legacy signal.

Maximizing power and spectral efficiencies for layered and conventional modulations

For use in a spacecraft for correcting amplifier distortion, a wideband distortion corrector avoids the need for directional couplers. The corrector includes a FET mounted in a miniature microwave-type housing. Signal flows through the source-to-drain channel. A gate impedance selected to be inductive at the operating frequency is coupled from the FET gate to the platform of the package, and may be simply a loop of bond wire. The channel connects by a strip transmission line to an amplifier, the distortion of which is to be corrected. For enhanced bandwidth, an inductor is coupled between the FET source and drain electrodes within the miniature housing. The platform of the package is coupled to the reference conductor of the transmission line. In one embodiment, direct bias voltage is applied by way of a bias tee across a strip transmission line and ground, and galvanic connections cause the bias to appear between the FET gate electrode and the channel.

Wideband integrated distortion equalizer

An integrated Ku-band linearizer driver amplifier for TWTAs with high gain and wide bandwidth

A new UHF Solid State Power Amplifier (SSPA) has been developed for a government mobile communications space program. The SSPA is capable of a peak power of 290 watts but will operate at a lower power of 135 Watts to provide the required linearity with WCDMA signals. Typical overall dc -RF efficiency is 42% at this operating point. The SSPA consists of an Input Amplifier with Command and Telemetry Electronics, a High Power Amplifier (HPA) section and an Electronic Power Converter (EPC). This paper begins by discussing the overall Satellite System Architecture, followed by details of the SSPA design and results from testing the Engineering Development Unit (EDU)

George Pallas

Papers

Wideband integrated distortion equalizer

An integrated Ku-band linearizer driver amplifier for TWTAs with high gain and wide bandwidth

UHF SSPA Design for WCDMA Space Applications