The photo-mask cost of standard-cell-based ASICs has been increased so prohibitively that low-volume production LSIs are difficult to fabricate due to high non-recurring engineering (NRE) cost including mask cost. Recently, user-programmable devices, such as FPGAs are started to be used for low-volume consumer products. However, FPGAs cannot be replaced for general purpose because of its lower speed-performance and higher power consumption. In this paper, we propose the user-programmable architecture called VPEX (Via Programmable logic device using EXclusive-or array), in which the hardware logic can be programmed by changing layout patterns on 2 via-layers. The logic element (LE) of VPEX consists of complex-gate-type EXclusive OR (EXOR) and Inverter (NOT) gates. The single LE can output 12 logics which include NOT, Buffer (BUF), all 2-inputs logic functions, 3-inputs AOI21 and inverted-output multiplexer (MUXI) by changing via-1 layout pattern. Furthermore, via-1 layout is optimized for high-throughput EB direct writing, so mask-less programming will be realized in VPEX. We compared the performance of area, speed, and power consumption of VPEX with that of standard-cell-based ASICs and FPGAs. As a result, the speed performance of VPEX was much better than FPGAs and about 1.3-1.6 times worse than standard-cells. We believe that the combination of VPEX architecture and EB direct writing is the best solution for low-volume production LSIs.

The clock recovery circuit is a key component in high-speed electrical time-division multiplexing (ETDM) transmission systems. In the case of clock extraction from non-return-to-zero (NRZ) signals, differentiation and full-wave rectification are indispensable. Exclusive OR/NOR circuits (XOR) are widely used for this purpose. In this paper, we describe an XOR IC fabricated with 0. 1-µm gate-length InAlAs/InGaAs/InP HEMTs for a 40-Gbit/s class clock recovery circuit. The IC was configured with a symmetrical Gilbert cell type XOR gate and two types of peaking techniques are used to achieve its high bit-rate. On-wafer-measurements indicate that the IC operates as fast as 80 Gbit/s and can extract a 40-GHz frequency component from 40-Gbit/s NRZ input signals. To confirm the feasibility of using the packaged XOR IC in clock recovery circuits, the conversion gain of the IC, which was operated as a differentiater and full-wave rectifier, was evaluated. Assuming that the input to the clock recovery circuit is a 1 Vp-p signal, the relatively high output power of -17 dBm can be obtained with low dependency on the length of the input pseudo-random bit streams. Furthermore, a clock recovery circuit was assembled using the packaged XOR IC, a waveguide filter and a commercial amplifier; it offers the practical system-bit-rate of 39. 81312 GHz with the low rms jitter of 900 fs.