Novel centre frequency and bandwidth control of RF LNA using two-tones phase delay

This paper presents a two-tone system to control the center frequency and bandwidth of an RLC tank in front-end LNAs. The control mechanism is based on the characteristic of an RLC tank, which induces a phase difference between the two frequencies. The proposed system is implemented on chip in the TSMC 0.18 μm CMOS technology. The LNA´s centre frequency and bandwidth were set at 2.45 GHz and 60 MHz, respectively. Precisions of 0.2% for centre frequency control and 8% for the bandwidth control were achieved. The two-tones phase delay principle can be generalized to tuning based on any information signal containing two tones with related phases and known frequencies.