Lunds universitet/Institutionen för elektro- och informationsteknik
Abstract
In this master thesis, combinations of noise-canceling LNA and harmonic-rejection mixers are investigated and compared to find an optimal inductorless receiver front-end for low-band (600-960MHz) FDD LTE-A network. The work was carried out in a modem development project at Ericsson Modems, Lund. Three receiver versions with different harmonic rejection techniques are compared in terms of noise figure (NF) and power consumption and the receiver with 6 LO phases is selected for optimization. The LNA combines noise cancellation for matching stage and nonlinearity cancellation for output stages so both low noise figure and high linearity are achieved. The final circuit show great potential for FDD LTE-A system with support up to 3 aggregated carriers for higher bandwidth. Low NF at 1.62 dB after the LNA and 1.75 dB after the mixer are observed from 0.4-1GHz. The LNA IIP2 is above 12 dBm and robust with process and temperature. Gain switching with possible reduction of 6 and 12 dB is integrated and the LNA linearity is not significantly suffered by low gain. Input return loss (S11) is better than -12dB regardless of gain, number of carriers and temperature (-30 – 110°C). Inductorless operation saves a lot of chip area and avoid dead package area, which then save cost and make the solution competitive.This master’s thesis done at Ericsson Modem aimed to investigate an inductorless receiver front-end for low-band LTE-A user terminals. The circuit combined noise-canceling technique and push-pull stage for LNA and harmonic-rejection technique for mixer, so three main issues of inductorless operation are solved. The issues include LNA noise and linearity, and noise folding effect caused by 3rd harmonics of LO signals
