This letter presents a 38/114 GHz switched-mode standing wave oscillator (SWO) capable of synchronous locking. Triple output frequency can be excited by digital control of different mode operations. The experimental prototype was fabricated using a low leakage 65 nm 1P9M triple-well CMOS technology. Incorporating a synchronous lock scheme, the measured phase noise from a 38 GHz carrier before and after the phase locked at 1 MHz offset are -102 dBc/Hz and -120 dBc/Hz, respectively. For the mode 1 operation at 38 GHz and mode 3 operation at 114 GHz, the experimental prototype consumes 4 and 20 mA, respectively, under a 1.2 V biasing voltage and with a chip size of 720 × 880 μm2.