A 0.12mm2 K/Ka Band RX Front-end in 40-nm CMOS with Inductor-Less LO Generators

This paper presents a broadband 18-33GHz receiver (RX) front-end with a core area of only 0.12mm
²
. In the local oscillator (LO) generators, a compact edge-combining (EC)-based frequency multiplication scheme is proposed to generate wideband and precise in-phase and quadrature (I/Q) LO signals at millimeter-wave frequencies. In the output stage of the LO chain, the switched-capacitor (SC) XOR modules triple the output clock frequency through edge-combining, which provides a 3× frequency reduction for the global clock distribution. The clock tripling is independently performed in I/Q differential LO signals, and the orthogonality of LO signals is not influenced by frequency multiplication. Implemented in TSMC 40nm GP CMOS, the proposed receiver core occupies only 0.46mm × 0.26mm. The RX front-end achieves a conversion gain of 42dB, a Noise Figure of 5.6dB, a baseband bandwidth of 100MHz, and an IQ phase variation < 1.3° (1σ interval, without calibration), while operating in the K/Ka band at 18-33GHz.