A Ka-Band 256-QAM Ninefold Sub-Harmonically Injection-Locked CMOS I/Q Modulator Using Pulsed Oscillator

In this paper, a Ka-band 256-QAM ninefold sub-harmonically injection-locked (SIL) I/Q modulator using frequency-tracking loop (FTL) and pulsed oscillator (P-OSC) is proposed using 90-nm CMOS process. The modulator consists of a P-OSC, a SIL quadrature voltage-controlled oscillator (SILQVCO), a FTL, and four reflection-type modulators. With the P-OSC, the sub-harmonic number can be enhanced up to 9. The proposed SILQVCO with FTL demonstrates a measured phase noise at 1-MHz offset frequency and the rms jitter integrated from 1 kHz to 40 MHz are -120 dBc/Hz and 36 fs, respectively. Between 25.9 and 27.1 GHz, the proposed modulator features an error vector magnitude (EVM) of within 3% for various quadrature amplitude modulations (QAMs), and the modulation can be up to 256-QAM scheme. This work is suitable for some advanced mm-wave applications due to its spurious modulation quality.