SiGe based amplifier outperforms other devices

The LTC6432-15 from Linear Technology is a wideband fully differential amplifier with 15dB gain. According to the company, recently acquired by Analog Devices, it offers a linearity of up to +50.3dBm at the output third-order intercept (OPI3dB), an output 1dB compression point (OP1dB) of +22.7dBm and a 3.2dB noise figure at 150MHz.

In addition to its signal-to-noise performance at high frequencies, it is said to maintain its dynamic range at lower frequencies, thanks to the significantly lower 1/f noise of SiGe. The company notes that noise rises to only 6.6dB at 100kHz, compared to more than 20dB for similar amplifiers.

Extending the useful bandwidth and dynamic range performance for applications that process low frequency signals, the LTC6432-15 offers better temperature stability and power supply ranges compared to GaAs and pHEMT amplifiers.

The LTC6432-15’s differential inputs and outputs are 100Ω terminated internally, while inputs are matched from 100kHz to 1.4GHz, with return loss over the full bandwidth said to be less than 10dB. The output is also matched from 100kHz to 1GHz.

The amplifier needs only DC blocking capacitors at its inputs and outputs, two chokes for proper biasing, plus one feedback capacitor per output to extend its excellent gain flatness to low frequencies. It comes in a 4 x 4mm plastic QFN package.

Graham Pitcher

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