Dual Channel Wideband Mixer with Programmable Gain Amplifiers for 4G/5G MIMO Receivers

Linear Technology has introduced a new wideband, high dynamic range dual channel mixer with an RF frequency range from 300 MHz to 6 GHz. The mixer is integrated with programmable variable gain IF amplifiers. The LTC5566, is a dual mixer with a very wide input frequency range, specifically optimized for the emerging 3.6 GHz and 4.5 GHz 5G bands, as well as the established 4G bands. Moreover, the device supports bandwidths up to 400 MHz to meet the needs of the growing sub-6 GHz 5G wireless access equipment.

This dual mixer has outstanding dynamic range, with Input P1dB of +11.5 dBm and Input IP3 of +25.5 dBm at 3.6 GHz. At higher frequencies, up to 5.8 GHz, its IIP3 sustains more than +24 dBm. The device’s integrated IF amplifier boosts the overall power conversion gain to a maximum of 12 dB. The gain of each channel is independently programmed in precise 0.5 dB steps via the on-chip SPI bus. So, with each channel driving an A/D converter, the fine gain control provides a simple means to balance the gain of the two channels and calibrate to the optimum level with minimal external components.

The LTC5566 is ideal for use in 5G wireless multichannel RRH (remote radio head) wireless access equipment that requires better performance and wider bandwidths at higher frequencies. Moreover, the device’s high level of integration enables high channel counts to be packed into a small enclosure. Other suitable applications include 4G LTE-Advanced, diversity receivers, distributed antenna systems and software-defined radio.

The LTC5566 is built on an active, double-balanced mixer core with no conversion loss and with excellent port-to-port isolation, reducing external RF filtering requirements. Each mixer input includes an integrated wideband balun transformer, allowing a simple single-ended interface. Using the SPI or parallel pins, the mixer inputs can be digitally tuned for optimum return loss over several wide, overlapping frequency bands, ranging from 1.3 GHz to 5.3 GHz, ensuring flexibility for use in software-defined radio applications without extra external components. The lower 450 MHz, 700 MHz and 900 MHz bands are also supported by the addition of a single external shunt inductor for proper matching, yielding superb dynamic range performance. Higher frequencies above 5.3 GHz, such as 5.8 GHz, can be achieved using a simple external matching circuit.