A Time-to-Digital Converter for Impulse Radio Pulse Width Modulator

This paper presents a high-resolution time-to-digital converter (TDC) for accurate pulse-width measurement of impulse radio pulse width modulation (IR-PWM) signals in wireless data acquisition systems. To improve timing resolution, the proposed TDC replaces conventional inverters with buffers in each delay stage, achieving a resolution of 2.94 ps and supporting an 8-bit dynamic range. An on-chip PWM generator is integrated to evaluate the TDC performance, generating pulse widths ranging from 400 ps to 830 ps. Fabricated in a 28-nm CMOS process, the TDC and PWM generator occupy areas of 14.3 µm × 405 µm and 14.3 µm × 6.3 µm, respectively. Operating at a 1 V supply, the TDC consumes 970 µW of power. Linearity tests show a differential nonlinearity (DNL) within ±0.55 LSB and an integral nonlinearity (INL) within ±1.5 LSB, confirming the accuracy of the proposed system.