Highly Linear Filtering TIA for 5G wireless standard and beyond

The demand for high data rates in emerging wireless standards is a result of the growing number of wireless device subscribers. This demand is met by increasing the channel bandwidth in accordance with historical trends. As MIMO technology advances, more bands and antennas are expected to be used. The most recent 5G standard makes use of mm-wave bands above 24GHz to expand the channel bandwidth. Channel bandwidth can exceed 2GHz when carrier aggregation is used. From the receiver’s point of view, this makes the baseband filter’s design, which is often a TIA, more difficult. This is due to the fact that as the bandwidth approaches the GHz range, the TIA’s UGBW should be more than 5GHz and it should have a high loop gain up to high frequencies. A closed-loop TIA with configurable bandwidth up to 1.5GHz is described in this scenario. Operational Transconductance Amplifier (OTA) closed in shunt-feedback is the foundation of the TIA. The proposed OTA is based on FeedForward topology (FF) together with inductive peaking technique to ensure stability rather than using the traditional Miller compensation technique. The TIA is able to produce GLoop unity gain bandwidth of 7.5GHz and high loop gain (i.e. 27dB @ 1GHz) using this method. The mixer and LNA’s linearity will benefit from this. Utilizing TSMC 28nm CMOS technology, a prototype has been created using this methodology. The output integrated noise from 20MHz to 1.5GHz is lower than 300μVrms with a power consumption of 17mW, and the TIA achieves In-band OIP3 of 33dBm. Additionally, a direct-conversion receiver for 5G applications is described. The 7GHz RF signal is down-converted to baseband by the receiver. Two cascaded LNTAs based on a common-gate transformer-based design make up the frontend. With an RF gain of 80mS and a gain variability of 31dB, it provides wideband matching from 6GHz to 8GHz. A double-balanced passive mixer is driven by the LNTA. The channel bandwidth from 50MHz to 2GHz is covered by two baseband paths. The first path, called as the low frequency path (LF), covers the channel bandwidth ranging from 50MHz to 400 MHz. In contrast, the second path, called as the high frequency path (HF), covers the channel bandwidth between 800MHz and 2GHz. Two baseband provide gain variability of 14dB, making the overall receiver able to have a gain configurability from 45dB to 0dB. Out-of-band (OOB) selectivity at 4 times the band-edge is greater than 33dB for each configurability. When the gain is at its maximum, the noise figure is less than 5.8dB, and the slope of the noise rise as the gain falls is less than 0.7dB/dB. The receiver guarantee an IB-OIP3 larger than 21dBm for any gain configuration. The receiver has been implemented in TSMC 28nm CMOS technology, consuming 51mW for LF path and 68mW for HF path. The measurement results are in perfect accordance with the requirements of the design.