Abstract
This work presents a theory of the resonator coupling network (RCN) and its application to a receiver front-end design. The RCN is able to couple energy from one resonator to the other efficiently at resonance frequencies. As the critical coupling condition is fulfilled at a precise coupling coefficient, capacitively coupled resonators (CCR) and inductively coupled resonators (ICR) can provide the maximum current gain (MCG) or maximum voltage gain (MVG) without any power consumption, equivalent to the same level by an ideal transformer. The advantage of using the CCR is that its coupling coefficient can be controlled accurately and robust to the process variation. On the other hand, the ICR not only can be implemented in a compact area but it can also act as a balun. Although the ICR cannot design the coupling coefficient as precisely as the CCR can, the analysis shows that its passive gain is insensitive to the coupling coefficient, an advantageous feature for on-chip transformer design. The high passive gain of the RCN makes it attractive for low power applications since it consumes no DC power. To verify the theory, the RCN is applied to the design of 2.4 GHz and 5.5 GHz receiver front-ends in 0.18 μm CMOS. The measured conversion gain of the 2.4 GHz and 5.5 GHz chips is 27.8 dB and 17.4 dB while dissipating 1.92 mW and 0.33 mW from 1.2 V and 0.6 V supplies, respectively.