The current trend is toward specifying linear power required at the amplifier output flange. This provides a concrete value for the link budget, and a straightforward method for comparing candidate power amplifiers while enabling optimization of prime power efficiency by evaluating the biggest power consumer in its likely operating condition.

The Indian amplifier market in India in the year 2010 was estimated at `30 crore with CPI, Xicom and Paradise Datacom (marketed by Eltel), and MCL (Miteq) being the major players. Major customers for the uplink amplifiers are Doordarshan, All India Radio, private broadcasters, and ISRO. Other major buyers include integrators for earth stations, teleports, and integrating DSNG vans.

The broadcast amplifier market can be classified into three major categories including audio, video, and radio frequency (RF). The highly reliable, solid-state power amplifiers (SSPA) based on leading-edge technologies like GaAs, LDMOS, and GaN are specialized for traveling wave tube amplifier (TWTA) replacements. Custom-designed and based on eutectic hybrid technology, state-of-the-art power amplifier modules have a longer lift-time and require less maintenance compared to classical TWTA solutions.

The two general categories of high-power amplifiers (HPAs) are used in SATCOM uplinks, vacuum-tube-based amplifiers, and solid-state amplifiers. For vacuum-tube amplifiers, including both TWTAs and klystron-tube power amplifiers (KPAs), the industry practice is to use the tube's saturated output power as the HPA's rated power. The TWTA's rated flange power is typically 0.5 dB to 0.7dB lower due to component losses in the amplifier's output section, i.e., the 750 W Ku-band TWTA provides 650 W RF power at the flange. SSPAs always use flange power, though there is a great variation in using Psat and P1dB in the industry.

In India, TWTAs dominate the market with a 75-80 percent market share, the balance being accounted for by SSPAs. Klystron amplifiers find application with DTH service providers who had seen major growth last year.

Audio power amplifiers are electronic amplifiers that take energy from power supply and control the output to match the input signal shape, but with greater amplitude. Audio power amplifiers may be segmented into class AB and class D products. Power amplifier circuits are classified as A, B, AB, and C for analog designs, and class D and E for switching designs based upon their conduction angle. Class AB and class D designs are most prevalent in audio power. Class D amplifiers have 90-95 percent efficiencies. Amplifier output quality is also determined by the power supply rejection ratio (PSRR), which specifies the ability of the amplifier to reject noise from power supply. The video amplifier amplifies a signal containing high-frequency components without introducing distortion. The RF video amplifier interfaces with the photodiode in the transceiver to provide the transition to a coaxial connector. As the second component in an RF video receiver, the RF amplifier must have low noise and low distortion in order to maintain exceptional signal integrity. The amplifier should also provide gain control for all video channels, including analog TV, digital TV, and VoD.

RF power amplifiers are commonly used in wireless communication devices to amplify and transmit radio frequency signals. RF transmission of an electrical signal requires corresponding power amplification for the intended transmission range. RF signals typically have a broad frequency spectrum from several megahertz to tens of gigahertz, and higher. A power amplifier amplifies a radio frequency signal at the output of a transmitter prior to transmission in a small-size communication device. A typical radio transmitter uses a RF power amplifier to amplify outbound signals for transmission by an antenna. RF power amplifiers are generally designed to provide maximum efficiency at the maximal output 
power.

Power amplifiers require a back-off in output power from their maximum level to meet specified linearity and not interfere with other signal transmissions. For TWTAs to meet linearity requirements, typical back-off is 6-7 dB below rated output power. For SSPAs, typical back-off to meet linearity is 2-4 dB below rated P1dB. Predistortion can increase the amount of linear power for both TWTAs and SSPAs, although the benefit is much greater with TWTAs. For most SSPAs, the small improvement gained from a linearizer does not justify the additional cost, although this is not the case at Ka-band where solid-state devices exhibit poor linearity characteristics compared with lower frequencies. For TWTAs, predistortion linearizers typically improve linear power by at least 3 dB. Linear operating power levels depend on the parameter specified, but linearized TWTAs generally require only 2-4 dB back-off to meet requirements.

The current trend is toward specifying linear power required at the amplifier output flange. This provides a concrete value for the link budget, and a straightforward method for comparing candidate power amplifiers while enabling optimization of prime power efficiency by evaluating the biggest power consumer in its likely operating condition.

Some of the major players in this industry in India are Amplus Communications, Anacom, Audionics, CPI, Codan, EAW, Kramer, Nautel, Richardson, and Xicom.

Amplus Communications is a leading manufacturer and supplier of RF amplifiers in India. They offer amplifiers in the power range from 1 to 250 W in almost all frequency bands, i.e., C, Ku, INSAT C, and Ka.

AnaCom designs and manufactures satellite communications equipment. Its solid state power amplifiers (AnaSat SSPAs) are highly integrated outdoor units, with full-featured monitor and controls, designed to give extremely reliable service in a wide range of environments. They are available in single or redundant configurations.

Audionics is marketed in India by Setron India Private Ltd. Some of the popular models in the category of distribution amplifiers include DA210E, DA210T, DA210D, DA116R, DA216R, 1683, 133, 1485, and 1622.

Communications & Power Industries' (CPI) crossed-field amplifiers (CFAs) are broadband, phase-stable microwave amplifiers used in coherent radar chains to efficiently generate very high peak output powers from relatively low input voltages which can be either applied to the cathode or an electrode similar to a TWTs cathode or grid pulsing, and in relatively small, lightweight packages.

EAW is represented by Aditya Infotech Limited in India. The products offered by the company include EAW CAZ800, EAW CAZ2500, EAW CAZ1400, EAW CAM80, and EAW CAM160.

Kramer Electronics is dedicated to developing creative, reliable and value oriented audio, video and computer signal processing solutions. Its product range includes 6505 high-performance distribution amplifier, PT-102AN high-performance audio distribution amplifier, VM-10HDxl high-performance distribution amplifier for HD-SDI signals, and VM-2HDMIxl distribution amplifier for HDMI signals.

Nautel is excited to be a participant in the expansion of broadcasting in India. The company has worked closely with local interests to ensure that its latest introductions address the specific needs of India's broadcasters. The high-frequency (HF) amplifiers are available in various power levels on standard ISM (industrial, scientific, and medical) operating frequency of 6.78 MHz.

Richardson Electronics has a rich and unique history of engineering solutions and distributing electronic components for the global RF and wireless communications markets. Its popular model is LD600-10.80 Res-Ingenium RF and MW Power Amplifier.

Xicom Technology is represented by Eltel Systems Private Limited in India. The company offers the world's most extensive product line of tube-based amplifiers. The Xicom amplifiers are highly regarded for their reliable output power and efficiency. Xicom traveling wave tube amplifiers, klystron power amplifiers, solid state power amplifiers, and block up-converters (BUCs) are used in broadcast applications where customers need to increase power and bandwidth.

This article is based on research conducted by Broadcast & Cablesat in February, 2011