Broadband sensing and spectroscopy in millimeter-wave and sub-THz frequencies can be facilitated with CMOS integrated circuits as low-cost, compact solutions. Wireless integrated systems in the mm-wave/THz regime pave the path for various novel applications, such as high-resolution imaging, broadband spectroscopy, and high-speed communication. Particularly, generation and detection of ultra-short picosecond pulses on silicon platforms have been of interest to researchers due to enhanced tunability and bandwidth of such signals. In this dissertation, silicon-based ultra-short pulse detectors are studied with special focus on two primary applications: wireless time transfer with sub-picosecond accuracy and broadband spectroscopy and sensing.

First, a self-mixing mm-wave impulse detector is introduced for high-accuracy wireless clock synchronization. Measurement results of the fabricated silicon chip demonstrate that a low-jitter sub-10GHz clock signal can be distributed among widely spaced nodes in a large-aperture array. Such a synchronized large-aperture array can enhance the angular resolution in imaging radars.

Secondly, a CMOS impulse detector with center frequency of 77 GHz is presented to achieve low-jitter inter-chip wireless time transfer. This impulse detector, which includes an on-chip slot planar inverted cone antenna, is based on a three-stage divide-by-8 injection-locked frequency divider. It is shown that a three-stage divider has better input sensitivity than a single-stage divide-by-8 divider. The output of the receiver is locked to the input repetition rate with an rms jitter of 0.29 ps. A wireless time transfer test with two impulse detector chips demonstrates that a low-jitter 9.5-GHz clock is distributed among widely spaced nodes in a large-aperture array.

Finally, a fully integrated coherent detector is introduced which uses a broadband frequency comb as a reference to detect mm-wave and sub-THz signals. The tunable frequency comb, which is generated by high-speed current switches, drives a passive field-effect transistor mixer to down-convert signals captured by an on-chip antenna. This system is capable of detecting any arbitrary spectrum from 50 to 280 GHz with a minimum resolution of 2 Hz. The detector circuit consumes a dc power of 34 mW, which makes it a low-power solution in comparison with conventional mm-wave/THz systems. This detector is utilized as a spectroscopic sensor to characterize different materials based on their responses to mm-wave signals.