Optimising the performance of wideband zero-IF receivers – VH3

Michiel Kouwenhoven – RF Design Manager, High Frequency Products

The zero-IF receiver architecture gains popularity in wireless applications because of its suitability to demodulate very wideband RF signals. This capability is important in digital pre-distortion (DPD) transmitters.

Realisation of sufficient dynamic range is commonly known to be a major issue of zero-IF architectures. DC offsets and second-order intermodulation products are both co-located in frequency with the signal of interest and therewith reduce the receiver sensitivity.

Linear Technology’s new LTC5584 and LTC5585 I/Q demodulators are capable of demodulating RF signals with more than 500MHz bandwidth, while maintain high receiver dynamic range. This is achieved though the unique capability of these demodulators to minimise DC offset and IM2 products in the baseband outputs through simple adjustment of a DC control voltage.