A 2.5-V 2.0-Gbyte/s 288-Mb packet-based DRAM with enhanced cellefficiency and noise immunity

A 2.5-V 288-Mb packet-based DRAM with 32 banks and 18-DQ organization architecture achieving a peak bandwidth of 2.0-GB/s at V _DD=2.25 V and T=100°C has been developed using (1) an area- and performance-efficient chip architecture with a mixture of high-speed interface circuits with DRAM peripheral circuits to increase cell efficiency; (2) a multilevel controlled bitline equalizing scheme and a distributed sense amplifier driving scheme to enhance DRAM core timing margin while increasing the number of cells per wordline for cell efficiency over the previous subwordline driving scheme; (3) a flexible column redundancy scheme with multiple fuse boxes instead of excessive spare memory cell arrays for 143 internal I/O architecture; and (4) optimized I/O circuits and pin parasitic design including pad and package to maximize the operating frequency     

A 2.5-V, 333-Mb/s/pin, 1-Gbit, double-data-rate synchronous DRAM

A double data rate (DDR) at 333 Mb/s/pin is achieved for a 2.5-V, 1-Gb synchronous DRAM in a 0.14-μm CMOS process. The large density of integration and severe device fluctuation present challenges in dealing with the on-chip skews, packaging, and processing technology. Circuit techniques and schemes of outer DQ and inner control (ODIC) chip with a non-ODIC package, cycle-time-adaptive wave pipelining, and variable-stage analog delay-locked loop with the three-input phase detector can provide precise skew controls and increased tolerance to processing variations. DDR as a viable high-speed and low-voltage DRAM I/O interface is demonstrated     

Dual-operating-voltage scheme for a single 5-V 16-Mbit DRAM

A dual-operating-voltage scheme (5 V for peripheral circuits and 3.3 V for the memory array) is shown to be the best approach for a single 5-V 16-Mb DRAM (dynamic random-access memory). This is because the conventional scaling rule cannot apply to DRAM design due to the inherent DRAM word-line boosting feature. A novel internal voltage generator to realize this approach is presented. Its features are the switching of two reference voltages, a driver using a PMOS-load differential amplifier, and the word-line boost based on the regulated voltage, which can ensure a wider memory margin than conventional circuits. This approach is applied to an experimental 16-Mb DRAM. A 0.5% supply-voltage dependency and 30-ns recovery time are achieved     

A 5-GByte/s data-transfer scheme with bit-to-bit skew control forsynchronous DRAM

This paper describes a 5-GByte/s data-transfer scheme suitable for synchronous DRAM memory. To achieve a higher data-transfer frequency, the properties were improved based on the frequency analysis of the memory system. Then, a bit-to-bit skew compensation technique that eliminates incongruent skew between the signals is described with a new, multioutput controlled delay circuit to accomplish bit-to-bit skew compensation by controlling transmission timing of every data bit. Simulated maximum data-transfer rate of the proposed memory system resulted in 5.1/5.8 GByte/s (321/365 MHz, ×64 bit, double data rate) for data write/read operation, respectively     

A 1.6-GByte/s DRAM with flexible mapping redundancy technique andadditional refresh scheme

We implemented 72-Mb direct Rambus DRAM with new memory architecture suitable for multibank. There are two novel schemes: flexible mapping redundancy (FMR) technique and additional refresh scheme. This paper shows that multibank reduces redundancy area efficiency. But with the FMR technique, this 16-bank DRAM realizes the same area efficiency as a single-bank DRAM. In other words, FMR reduces chip area by 13%. This paper also describes that additional refresh scheme reduces data retention power to 1/4. Its area efficiency is about four times better than that of the conventional redundancy approach     

A 4-Mbit DRAM with trench-transistor cell

An experimental 5-V-only 1M-word/spl times/4-bit dynamic RAM with page and SCD modes has been built in a relatively conservative 1-/spl mu/m CMOS technology with double-level metal and deep trenches. It uses a cross-point one-transistor trench-transistor cell that measures only 9 /spl mu/m/SUP 2/. A double-ended adaptive folded bit-line architecture used on this DRAM provides the breakthrough needed to take full density advantage of this cross-point cell. The 30-fF storage capacitance of this cell is expected to provide high alpha immunity since the charge is stored in polysilicon and is oxide isolated from the substrate. A 150-ns now-address-stable access time and 40-ns column-address-strobe access time have been observed.     

A reliable 1-Mbit DRAM with a multi-bit-test mode

A single 50V supply 1-Mb DRAM using a half V/SUB cc/ biased memory cell with a reduced electric field of 2 MV/cm and a shared sensing scheme for reasonable cell signal is described. A testability concept which allows 1/4 reduced test time, page/nibble functions including a continuous nibble mode, and an effective redundancy circuit are also described. A typical access time of 90 ns has been obtained using a titanium polycide world-line technology.     

A 16-Mbit DRAM with a relaxed sense-amplifier-pitch open-bit-linearchitecture

A 16-Mb dynamic RAM has been designed and fabricated using 0.5-μm CMOS technology with double-level metallization. It uses a novel trench-type surrounding high-capacitance cell (SCC) that measures only 3.3-μm² in cell size with a 63-fF storage capacitance. A novel relaxed sense-amplifier-pitch (RSAP) open-bit-line architecture used on the DRAM achieves a high-density memory cell array, while maintaining a large enough layout pitch for the sense amplifier. These concepts allow the small chip that measures 5.4×17.38 (93.85) mm² to be mounted in a 300-mil dual-in-line package with 65-ns RAS access time and 35-ns column address access time     

A 1.0-V 230-MHz column access embedded DRAM for portable MPEGapplications

This paper describes a 32-Mb embedded DRAM macro fabricated using 0.13-μm triple-well 4-level Cu embedded DRAM technology, which is suitable for portable equipment of MPEG applications. This macro can operate 230-MHz random column access even at 1.0-V power supply condition. The peak power consumption is suppressed to 198 mW in burst operation. The power-down standby mode, which suppresses the leakage current consumption of peripheral circuitry, is also prepared for portable equipment. With the collaboration of array circuit design and the fine Cu metallization technology, macro size of 18.9 mm² and cell efficiency of 51.3% are realized even with dual interface and triple test functions implemented     

A 20-ns 128-kbit×4 high speed DRAM with 330-Mbit/s data rate

The authors describe a high-speed DRAM (HSDRAM), designed primarily for high performance, while retaining the density advantage of the one-transistor DRAM cell. The 128-kb×4, 78-mm² chip shows a random access time of 20 ns and a column access time of 7.5 ns, measured at 5.0 V, 25°C, and 50-pF load. A 256-b×4 high-speed page mode is provided which has 12-ns cycle into 60 pF, resulting in a data rate of 330 Mb/s. Additional measurements on HSDRAM further demonstrate that DRAM operation in a high-speed regime is not precluded by noise, power, wiring delay, and soft error rate. The device is implemented in a 1.0 μm n-well CMOS process     

A 2.5-V, 12-b, 5-MSample/s pipelined CMOS ADC

A set of power minimization techniques is proposed for pipelined ADC's. These techniques include commutating feedback-capacitors, sharing of the op-amp between the adjacent stages of the pipeline, reusing the first stage of the op-amp as comparator pre-amp, and exploiting parasitic capacitors for common-mode feedback. This set of low-power design techniques is incorporated in an experimental chip fabricated in a 1.2-μm, double-poly, double-metal CMOS process. At 12-b 5-Msample/s, the chip dissipates 33 mW of power from a 2.5-V analog supply while achieving a maximum differential nonlinearity (DNL) of -0.78 and +0.63 least-significant bits (LSB) with a peak signal-to-noise ratio (SNR) of 67.6 dB     

A 1-Mbit DRAM with 33-MHz serial I/O ports

High-speed operation, a 33-MHz serial cycle, and a 10-ns serial data access time have been realized by internal serial/parallel conversion circuits, a newly designed I/O controller circuit, new dynamic register circuits, a divided sensing method, and an optimized layout design. The chip is fabricated with a 1.2-/spl mu/m double-level polysilicon and double-level aluminium n-channel MOS process technology. An optimized interlevel insulator realizes equivalent first- and second-level aluminium pitches for a compact chip design. The chip size is 5.88/spl times/11.2 mm/SUP 2/. This memory has high-speed input and output capability as well as random accessibility. These features are suitable for TV and VCR frame-memory-system applications.     

A 60-ns 16-Mbit CMOS DRAM with a transposed data-line structure

Low-noise, high-speed circuit techniques for high-density DRAMs (dynamic random-access memories), as well as their application to a single 5-V 16-Mb CMOS DRAM with a 3.3-V internal operating voltage for a memory array, are described. It was found that data-line interference noise becomes unacceptably high (more than 25% of the signal) and causes a serious problem in 16-Mb DRAM memory arrays. A transposed data-line structure is proposed to eliminate the noise. Noise suppression below 5% is confirmed using this transposed data-line structure. A current sense amplifier is also proposed to maintain the data-transmission speed in common I/O lines, in spite of a reduced operating voltage and increased parasitic capacitance loading in the memory array. A speed improvement of 10 ns is achieved. Using these circuit techniques, a 16-Mb CMOS DRAM with a typical RAS access time of 60 ns was realized     

A 2.5 V CMOS delay-locked loop for 18 Mbit, 500 megabyte/s DRAM

This paper describes clock recovery circuits specifically designed for the hostile noise environment found aboard dynamic RAM chips. Instead of a phase-locked loop having a voltage-controlled oscillator, these circuits implement a delay-locked loop, thereby achieving low jitter and reduced sensitivity to noise on the substrate and the power supply rails. Differential signals are employed both in signal paths and in control paths, further decreasing noise sensitivity and simultaneously allowing operation from low voltage supplies. An unorthodox voltage controlled phase shifter, operating on the principle of quadrature mixing, yields a circuit with unlimited delay range (modulo 2π radians). Minor loops, enclosed within the overall loop feedback path, perform active duty cycle correction. Measured results show peak-to-peak jitter of 140 ps on the internal clock signal, and 250 ps on the external data pins, sufficiently small to allow 500 Megabyte/s transfer rates at the I/O interface     

A 1.2-V 1.5-Gb/s 72-Mb DDR3 SRAM

A 1.2-V 72-Mb double data rate 3 (DDR3) SRAM achieves a data rate of 1.5 Gb/s using dynamic self-resetting circuits. Single-ended main data lines halve the data line precharging power dissipation and the number of data lines. Clocks phase shifted by 0/spl deg/, 90/spl deg/, and 270/spl deg/ are generated through the proposed clock adjustment circuits. The latter circuits make input data sampled with an optimized setup/hold window. On-chip input termination with a linearity error of /spl plusmn/4.1% is developed to improve signal integrity at higher data rates. A 1.2-V 1.5-Gb/s 72-Mb DDR3 SRAM is fabricated in a 0.10-/spl mu/m CMOS process with five metals. The cell size and the chip size are 0.845 /spl mu/m/sup 2/ and 151.1 mm/sup 2/, respectively.     

A 2.6-GByte/s multipurpose chip-to-chip interface

A 2.6 GByte/s megacell that interfaces to single or double byte wide DRAMs or logic chips is implemented using 0.35-0.18 μm CMOS technologies. Special I/O circuits are used to guarantee 800 Mbit/s/pin data rate. Microwave PC board design methodologies are used to achieve the maximum possible interconnect bandwidth     

A 65-ns 4-Mbit CMOS DRAM with a twisted driveline sense amplifier

A 4-Mb word/spl times/1-b/1-Mb word/spl times/4-b CMOS DRAM characterized by a twisted driveline sense-amplifier (TDSA) scheme and a multiphase drive circuit which enable faster access time and a smaller peak power supply current, respectively, is described. The implementation of an initialize mode with CAS-before-RAS (CBR) logic control, which reduces the memory-chip initialization time by almost a thousand times, is also discussed. The chip measures 6.38/spl times/17.38 mm/SUP 2/ and has been fabricated by using double-well CMOS technology with a minimum design rule of 0.8 /spl mu/m. A typical access time of 65 ns and a peak power supply current of less then 150 mA have been obtained.     

A 60-ns 3.3-V-only 16-Mbit DRAM with multipurpose register

A single 3.3-V 16-Mbit DRAM with a 135-mm/sup 2/ chip size has been fabricated using a 0.5- mu m twin-well process with double-metal wiring. The array architecture, based on the twisted-bit-line (TBL) array, includes suitable dummy and space word-line configurations which suppress the inter-bit-line noise and bring yield improvement. The multipurpose register (MPR) designed for the hierarchical data bus structure provides a line-mode test (LMT), copy write, and cache access capability. The LMT with on-chip test circuits using the MPR and a comparator creates a random test pattern and reduces the test time to 1/1000. A field shield isolation and a T-shaped stacked capacitor allow the layout of a 4.8- mu m/sup 2/ cell size with a storage capacitance of 35 fF. These techniques enable the 3.3-V 16-Mbit DRAM to achieve a 60-ns RAS access time and 300-mW power dissipation at 120-ns cycle time.<>     

A 60-ns 4-Mbit CMOS DRAM with built-in selftest function

A 4-Mb CMOS DRAM measuring 6.9/spl times/16.11 mm/SUP 2/ has been fabricated using a 0.9-/spl mu/m twin-tub CMOS, triple-poly, single-metal process technology. N-channel depletion-type trench cells, 2.5/spl times/5.5 /spl mu/m/SUP 2/ each, are incorporated in a p-well. A novel built-in selftest (BIST) function which enables a simultaneous and automatic test of all the memory devices on a board is introduced to reduce the RAM testing time in a system. This function is effective for system maintenance and a daily start-up test even in a relatively small system. A high-speed low-power 4-Mb CMOS DRAM with 60-ns access time, 50-mA active current, and 200-/spl mu/A standby current is realized by widening the DQ line bus which connects the sense amplifiers with DQ buffers, thereby reducing the parasitic capacitance of the DQ lines.     

A 2.5-V 45-Gb/s decision circuit using SiGe BiCMOS logic

A 45-Gb/s BiCMOS decision circuit operating from a 2.5-V supply is reported. The full-rate retiming flip-flop operates from the lowest supply voltage of any silicon-based flip-flop demonstrated to date at this speed. MOS and SiGe heterojunction-bipolar-transistor (HBT) current-mode logic families are compared. Capitalizing on the best features of both families, a true BiCMOS logic topology is presented that allows for operation from lower supply voltages than pure HBT implementations without compromising speed. The topology, based on a BiCMOS cascode, can also be applied to a number of millimeter-wave (mm-wave) circuits. In addition to the retiming flip-flop, the decision circuit includes a broadband transimpedance preamplifier to improve sensitivity, a tuned 45-GHz clock buffer, and a 50-/spl Omega/ output driver. The first mm-wave transformer is employed along the clock path to perform single-ended-to-differential conversion. The entire circuit, which is implemented in a production 130-nm BiCMOS process with 150-GHz f/sub T/ SiGe HBT, consumes 288 mW from a 2.5-V supply, including only 58 mW from the flip-flop.