A 0.46mm2 4dB-NF unified receiver front-end for full-band mobile TV in 65nm CMOS

This paper describes a unified receiver front-end (RFE) for mobile TV covering the VHF-III (174 to 248MHz), UHF (470 to 862MHz) and L (1.4 to 1.7GHz) bands. The RFE (Fig. 9.7.1) is tailored to avert any external balun, or dedicated narrow-band radios, commonly found in prior arts. The featured advances are threefold: 1) a gain-boosting current-balancing balun-LNA addresses the imbalanced bias current (I_cs=4I_cg) and load (R_cg=4R_cs) conditions of the noise canceling balun-LNA, improving IIP2 and wideband output balancing while eliminating output buffers; 2) a current-reuse mixer-LPF realizes quadrature/ harmonic-rejection (HR) mixing and 3^rd-order current-mode post filtering in one block, enhancing linearity and noise just where both are demanding, while saving power and area; 3) a direct injection-locked 4-/8-phase LO generator (LOG) relaxes the master LO frequency (f_LO) by avoiding frequency division. A high f_LO has been the speed limit of wideband RFEs with HR, where a 7.2GHz f_LO is employed for 0.9GHz RF reception after divide-by-8. Here, the LOG uses 2 chains of 8-phase corrector (8PC) and 1 chain of 4-phase corrector (4PC) to optimize the phase precision in each band. A master LO_in (e.g., from VCO) injection locks either one of the chains to synthesize a 4/8-phase LO_out at f_LO. This LOG scheme particularly suits this application, as the problem of VCO pulling is irrelevant here in the absence of the PA.