All-digital TAD-OFDM detection for sensor interface using TAD-digital synchronous detection

Abstract

An all-digital TAD-OFDM detection method for sensor interface with digital synchronous detection based on TAD (Time AID converter)-type ADC is introduced. A TAD basic structure is a completely digital circuit including a ring delay-line (RDL) with delay units (DUs) driven by an input voltage Vio and an RDL frequency counter, latch and encoder. Since the operating principle is to count the number of DUs through which the delay pulse passes within a sampling period T., this ADC (TAD) naturally performs as a Vio voltage integration circuit for T •. Hence, high frequency noises can be removed simultaneously with AID conversion. First, as an example of a voltage-integration effect as a low-pass tiIter, magnet pick-Up sensing was verified using a 22-bit TAD test chip fabricated using a 0.65-Jlm CMOS with 106 JlV/LSB (100 kS/s). Next, the idea of digital synchronous detection with TAD (called TAD-DSD with the voltage-integration effect) is proposed. Finally, by using the TAD-DSD principle, TAD OFDM detection is presented and experimentally confirmed, resulting in signal-detection of each wave-amplitude from a four-carrier-composite wave, which consists of frequencies, 1.6-, 3.2-, 6.4-and 12.8-MHz, respectively.

All-digital MEMS tuning-fork self-excited vibration control by phase-relation using TAD-based ADPLL

“…Thus, the all-digital MEMS tuning-fork self-excited vibration control method can replace conventional analog vibration-control methods unsuitable for very scaling with lower-supply voltage. Finally, we confirmed angular-rate measured sensitivity of 0.14(º/s)/LSB and noise peaks of approximately ±0.18º/s at BW = 10Hz using the TAD-DSD method [8].…”

“…Figure 9 shows measured jitter levels of (a) Pdr-pulse-train, (b) Pmo-pulse-train and (c) phase-difference between Pmo and Pdr with measured σ = 21.6ns, 52.6ns and 69.7ns, respectively. These jitter levels are small enough compared with MEMS element resonance periods (37µs, for example) for achieving TAD-DSD methods [8]. Thus, the all-digital MEMS tuning-fork self-excited vibration control method can replace conventional analog vibration-control methods unsuitable for very scaling with lower-supply voltage.…”

“…The latter will be presented in the near future. Incidentally, for achieving angular-rate signal detection with all-digital synchronous detection using timedomain processing, we can use TAD-digital synchronous detection (TAD-DSD) presented in [8].…”

Decoupling Control of Micromachined Spinning-Rotor Gyroscope with Electrostatic Suspension

“…Therefore, it is necessary to design and realize decoupling control of the dual-axis angular rate gyroscope that aims to achieve tactical-grade level or better performance. Currently, most of the reported results focus on microfabrication and device optimization [17,20,23], capacitive position sensing [24,25,26] and suspension control [18,27,28], rotor spin-up [21,28,29], design of the gyro rebalance loop [21,30] and error analysis of the gyro [31]. Little work has been reported on the cross-axis coupling effect, nor the decoupling control of the micromachined spinning rotor gyroscopes with electrostatic suspension.…”