A field-programmable mixed-signal IC for fast-prototyping and low-cost production of mixed-signal system is presented. The IC contains time-domain configurable analog blocks (TCABs) that can be programmed into a time-to-digital converter (TDC), digitally controlled oscillator (DCO), digitally controlled delay element, digital pulse-width modulator (DPWM), or phase interpolator (PI). The prototype IC fabricated in 65-nm CMOS demonstrates its versatile programmability with the successful operations as a 1-GHz PLL with 12.3-psrms integrated jitter, 50-MS/s ADC with 32.5-dB SNDR, and 1.2-to-0.7V DC-DC converter with 95.5% efficiency.