Yoshinori Shirakawa

A 14.6 th -order 3.456GHz transmit baseband filter in 110nm CMOS for millimeter-wave communication systems

This paper presents a 1.728Gbps transmit baseband filter for transmitters of millimeter-wave communication systems. In order to avoid the inter symbol interference, ultra wide band and very high order filter is demanded. It is impracticable to realize such a high order filter with conventional analog technique, such as gm-C filter. The proposed filter consists of a 3.456GHz digital filter followed by an 8-bit 3.456Gsps digital to analog converter (DAC), which occupies 0.265mm2 in 110nm CMOS processes. It is difficult to adjust the clock and data delay at 3.456GHz. The DAC has a clock divider for the high speed operation. The new filter consumes 142mW and achieves the transmit spectrum very close to the mask regulated by IEEE802.15.3c.

Quasi-Synchronous Sampling and Adaptive Partial-Response Maximum-Likelihood Read-Channel System

We propose a read-channel system with quasi-synchronous sampling and an adaptive partial-response maximum-likelihood (PRML) method to achieve accurate timing recovery and correct data extraction under high-density recording with a high transfer rate. The proposed system can extract data correctly in the state of either oversampling or undersampling using first-in-first-out flip-flops (FIFOs) and an asynchronously sampled data processable maximum-likelihood detector (ASML). In other words, it allows a sampling clock to be incompletely synchronized with a channel bit. Furthermore, the ASML adaptively learns the references required for calculating branch metrics even though the input data are not synchronized with the channel bit. This system achieves stable data extraction under quasi-synchronous sampling, improves the bit-error-rate performance, and can be applied to next-generation, high-density, and high-transfer-rate storage systems.