Amplifier drives high sampling rate A/D converters.

Press Release Summary:

Model LT5514 850 MHz, programmable-gain, broadband amplifier exhibits output 3rd order intercept of 49 dBm at 70 MHz. It has 2nd and 3rd order distortion products lower than -87 dBc, while delivering 2 V peak-to-peak output into 200 ohm load. Variable gain is adjusted by on-chip, digitally controlled attenuator in combination with fixed gain amplifier. Unit is suited for 12- and 14-bit, 65 MS/sec or faster A/D converters in communication systems.

Original Press Release:

Broadband Programmable Gain Amplifier Delivers High Output Level with Ultra-Low Distortion

Device Drives High Sampling Rate A/D Converters

MILPITAS, CA - June 21, 2004 - A new 850 MHz programmable gain, broadband amplifier from Linear Technology Corporation has the best distortion characteristics of any amplifier in its class. The LT5514 exhibits an output third-order intercept (OIP3) of 49dBm at 70MHz, and has 2nd and 3rd order distortion products lower than -87dBc, while delivering 2V peak-to-peak output into a 200-Ohm load. Its combination of low noise and high spurious-free output capability makes it the driver of choice for 12- and 14-bit, 65Msps or faster A/D converters in high performance communication systems. The high performance of the LT5514 makes it ideal for a range of applications, including ADC drivers, IF amplifiers for cellular basestation receivers, amplifier/drivers for basestation transmitter distortion correction loops and amplifiers for cable headend upstream receivers.

The LT5514's variable gain is adjusted by means of an on-chip, digitally controlled attenuator in combination with a fixed gain amplifier. A 4-bit parallel input word provides accurate gain control, ranging from 10.5dB to 33dB, with a 1.5dB incremental step.

The LT5514 has a differential input and output topology, providing a balanced drive to an A/D converter, while preserving its very low distortion characteristics. Even with 50 Ohm loads, the amplifier output can swing more than 3Vp-p to match any A/D converter's input voltage range. As an amplifier, the LT5514 has a gain flatness of +/- 1dB over a 450MHz bandwidth. Meanwhile it introduces very little group delay, reducing phase distortion over a wide operating frequency.

The LT5514 contains two output amplifiers connected in parallel. Optimal distortion performance is achieved when both amplifiers are operating. However, the device can operate in a reduced power mode by selectively turning off one of the internal amplifiers, reducing the supply current by about 50%, yet still providing 43dBm OIP3 at 70MHz.

The LT5514 comes in a 20-pin plastic TSSOP package. The price in 1,000 piece quantities is $5.20. The product is available from stock.

Summary of Features: LT5514
o Output IP3 at 100MHz: 47dBm
o Maximum Output Power: 21dBm
o Bandwidth: LF to 850MHz
o Propagation Delay: 0.8ns
o Maximum Gain: 33dB
o Noise Figure: 7.3dB (Max Gain)
o Gain Control Range: 22.5dB
o Gain Control Step: 1.5dB

Company Background
Linear Technology Corporation was founded in 1981 as a manufacturer of high performance linear integrated circuits. Linear Technology products include high performance amplifiers, comparators, voltage references, monolithic filters, linear regulators, DC-DC converters, battery chargers, data converters, communications interface circuits, RF signal conditioning circuits, and many other analog functions. Applications for Linear Technology's high performance circuits include telecommunications, cellular telephones, networking products such as optical switches, notebook and desktop computers, computer peripherals, video/multimedia, industrial instrumentation, security monitoring devices, high-end consumer products such as digital cameras and MP3 players, complex medical devices, automotive electronics, factory automation, process control, and military and space systems.

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