An ultrahigh dynamic range RF down-converting mixer has been released by Linear Technology Corporation for high performance applications. The new device is the LTC5551 and is said to offer very high linearity of +36dBm IIP3, (input third-order intercept), and low 9.7dB noise figure comparable to the highest IIP3 passive mixers available. This device offers 2.4dB of conversion gain, which can substantially improve receiver dynamic range. The device also has broad RF frequency range capability, operating from 300MHz to 3.5GHz.
Additionally, passive mixers require high LO (local oscillator) drive to reach their claimed IIP3. This device has an integrated LO buffer requiring only 0dBm drive level, hence external circuitry and costs are minimised. And with the elimination of a high power LO signal in the users’ receiver, it substantially reduces a potential source of undesirable radiation, thus simplifying filtering and RF shielding requirements.
The solution offers robust radio performance with a high 1dB compression point of +18dBm. Both the RF and LO inputs have integrated balun transformers. The mixer is powered from a single 3.3V supply with current consumption of 204mA, delivering its high performance with exceptionally low power. If needed, the mixer also has a low power mode controlled via the ISEL pin. In this mode, current consumption drops by 30% to 142mA, trading off the IIP3 slightly to +29.3dBm.
The performance capabilities of this mixer means it is ideally suited for a wide range of mission-critical, high performance applications that are exposed to strong interference sources such as multi-carrier GSM, 4G LTE and LTE-Advanced multimode basestations, point-to-point backhauls, military communications, wireless repeaters, public safety radios, VHF/UHF/white-space broadcast receivers, radar and avionics.
The mixer can be conveniently shut down with an enable control pin. When disabled, the IC draws a maximum of 100µA standby current. The device turns on and off in 500ns, suitable for burst-mode receivers.
Linear Technology
www.linear.com/product/LTC5551
