Analysis of BiCMOS buffer for input voltages with finite rise time

A BiCMOS digital logic gate is analyzed for input voltages with a finite rise or fall time. A new gate delay model to account for the input slope is developed. A set of accurate yet simple closed-form delay expressions are derived for the first time in terms of the input signal slew rate as well as circuit and device parameters. SPICE simulations are used to verify the accuracy of the analytical delay model. The BiCMOS circuit is characterized in terms of the input slew rate, the fan-in, fan-out, and the circuit delay constants. The model can be incorporated in timing simulators and timing analyzers for BiCMOS ULSI circuit design     

A delay model and optimization method of a low-power BiCMOS logiccircuit

A new delay model and optimization method is proposed for a low-power BiCMOS driver. A transient overdrive, base directly-tied complementary BiCMOS logic circuit operates faster than conventional BiCMOS and CMOS circuits for supply voltage down to 1.5 V by using a speed-power-area optimization approach. An analytical delay expression is derived for the first time for a full-swing BiCMOS circuit with short-channel effects. The circuit is simulated with a HSPICE model using 0.8-μm BiCMOS technology with a 6-GHz n-p-n and a 1-GHz p-n-p transistor. The simulation results have verified the analytical results and demonstrated that the circuit can work up to 200 MHz operating frequency for a load capacitance of 1 pF at 1.5 V of supply voltage     

Accurate delay models for digital BiCMOS

A detailed transient analysis of the MOSFET-BJT combination prevalent in digital BiCMOS gates is presented. The analysis accounts for high-level injection leading to BJT β roll-off, base pushout leading to BJT f_T roll-off, short-channel behavior of the MOS drain current, and parasitic capacitances at the base and output. Based on the transient analysis, a piecewise delay expression is derived that shows excellent agreement with measured gate delay and with SPICE simulated delay. The comparisons are made for a wide range of circuit parameters in the gate, namely, MOSFET/BJT size, load capacitance, and supply voltage for both 1- and 0.6-μm BiCMOS technologies. The model is used to optimally size gates, and to determine circuit and device design guidelines to minimize the delay degradation at reduced supply     

Analysis and optimization of BiCMOS gate circuits

A comprehensive view of an optimization strategy for BiCMOS gates is described. A simple gate delay model is proposed. BiCMOS gate delay, when optimized, is found to be expressed as A+B√F, where F is fanout and A and B are coefficients. Since the coefficients can be extracted by SPICE simulation, the delay prediction can be precise, while keeping the delay formula simple enough for circuit designers to derive useful expressions. A procedure for optimizing BiCMOS gates is studied. BiCMOS gate delay can be calculated quickly and optimized efficiently just by looking up a design table which is obtained from SPICE simulations. The procedure for making the design table is technology-independent. Once obtained, the design table can be applied to any design with the same device technology. A sizing strategy of cascaded BiCMOS buffers is derived from the simple delay model. In a 0.8 μm, 9 GHz, BiCMOS process, a BiCMOS-BiCMOS cascaded buffer is optimized when the scale-up factor between two consecutive stages is e ^2.3(≈10.0). A BiCMOS-CMOS cascaded buffer becomes the fastest when the scale-up factor, e^1.6(≈5.0), is employed. The optimization procedure and the sizing strategy can be used for several variants of the basic BiCMOS gate, because the delay model is based on basic circuit models for the variants     

Physical timing modeling for bipolar VLSI

An approach for the analytical timing modeling of bipolar VLSI circuits that is based on average branch current analysis and the parametric correction scheme is presented. The combination of these techniques permits complex delay-sensitive effects of bipolar digital circuits to be incorporated in the derivation of the bipolar delay models. The delay functions of two basic bipolar subcircuit configurations (the series-gated structure and the emitter follower) are derived using the proposed techniques. It is shown that accurate timing information for the high-speed bipolar digital circuit, such as ECL, CML, and BiCMOS, can be obtained by repeated processing of these subcircuit delay functions. The delay estimates obtained with these timing models have been shown to be accurate typically within 10% of SPICE estimates. Applications include switch-level timing simulation, timing analysis and verification cell optimization, and technology mapping     

An accurate analytical BiCMOS delay expression and its applicationto optimizing high-speed BiCMOS circuits

A scheme for optimizing the overall delay of BiCMOS driver circuits is proposed in this paper. Using this optimization scheme, it is found that the delay is minimized when the maximum collector current of the bipolar transistors is equal to the onset of high current effects. Using this assumption, an accurate BiCMOS delay expression is derived in terms of the bipolar and MOS device parameters. The critical device parameters are then identified and their influence on the circuit speed discussed. An overall circuit delay expression for optimizing BiCMOS buffers is derived and a comparison made with CMOS buffers. It is shown that BiCMOS circuits have a speed advantage of 1.7 or an area advantage of about 5 for 2-μm feature sizes. In order to predict the future performance of BiCMOS circuits, a figure of merit is derived from the delay expression. Using the figure-of-merit expression, it is seen that future BiCMOS circuits can keep the speed advantage over CMOS circuits down to submicrometer dimensions under constant load capacitance assumption     

Testable design of BiCMOS circuits for stuck-open fault detectionusing single patterns

Single BJT BiCMOS devices exhibit sequential behavior under transistor stuck-OPEN (s-OPEN) faults. In addition to the sequential behavior, delay faults are also present. Detection of s-OPEN faults exhibiting sequential behavior needs two-pattern or multipattern sequences, and delay faults are all the more difficult to detect. A new design for testability scheme is presented that uses only two extra transistors to improve the circuit testability regardless of timing skews/delays, glitches, or charge sharing among internal nodes. With this design, only a single vector is required to test for a fault instead of the two-pattern or multipattern sequences. The testable design scheme presented also avoids the requirement of generating tests for delay faults     

Design and optimization of buffer chains and logic circuits in aBiCMOS environment

The design and optimization of BiCMOS buffer chains and multi level logic circuits are reported. BiCMOS speedup contours are introduced and analytical expressions for the delay are obtained. The speedup contours and the delay expressions were used in the design and optimization of BiCMOS buffer chains. Also, general design guidelines, which can be easily automated, for circuit design in a BiCMOS environment are given. Designing multistage mixed CMOS/BiCMOS buffers, BiCMOS complex logic gates, and multi level CML (current mode logic) gates is also studied     

Study of BiCMOS logic gate configurations for improved low-voltageperformance

A simple BiCMOS configuration employing the source-well tie PMOS/n-p-n pull-down combination is proposed for low-voltage, high-performance operations. The improved BiCMOS gate delay time over that of the NMOS/n-p-n (conventional) BiCMOS gate is confirmed by means of inverter simulations and measured ring oscillator data. The source-well tie PMOS/n-p-n BiCMOS gate outperforms its conventional BiCMOS counterpart in the low-voltage supply range, at both high and low temperatures. A critical speed path from the 68030 internal circuit is used as a benchmark for the proposed BiCMOS design technique. The measured propagation delay of the BiCMOS speed path is faster than its CMOS counterpart down to 2.3 V supply voltage at -10°C and sub-2 V at 110°C     

BiCMOS logic circuit for single-battery operation

A novel BiCMOS logic circuit is described that provides highspeed rail-to-rail operation with only one battery cell (1-1.5 V). The proposed circuit utilises a novel pull-down scheme that involves bootstrapping the base of the pull-down p-n-p bipolar junction transistor to a negative potential during the pull-down transient period. Circuit simulations have shown that the proposed circuit outperforms the transient-saturation full-swing BiCMOS and the bootstrapped bipolar circuits in terms of delay, power and cross-over capacitance for all simulated supply voltages     

An ultra-high-speed ECL-BiCMOS technology with silicon filletself-aligned contacts

We have developed a half-micron super self-aligned BiCMOS technology for high speed application. A new SIlicon Fillet self-aligned conTact (SIFT) process is integrated in this BiCMOS technology enabling high speed performances for both CMOS and ECL bipolar circuits. In this paper, we describe the process design, device characteristics and circuit performance of this BiCMOS technology. The minimum CMOS gate delay is 38 ps on 0.5 μm gate and 50 ps on 0.6 μm gate ring oscillators at 5 V. Bipolar ECL gate delay is 24 ps on 0.6 μm emitter ring oscillators with collector current density of 40 kA/cm². A single phase decision circuit operating error free over 8 Gb/s and a static frequency divider operating at 13.5 GHz is demonstrated in our BiCMOS technology     

An analytical transient model for a 1.5 V BiCMOS dynamic logiccircuit for low-voltage deep submicrometer BiCMOS VLSI

This paper presents an analytical transient model for the 1.5 V BiCMOS dynamic logic circuit using Gummel-Poon charge control model for deep submicrometer BiCMOS VLSI. Based on the analysis, the switching time of the 1.5 V BiCMOS dynamic circuit is sensitive to the forward transit time with a large load capacitance. With a small load capacitance, its switching time is related to the threshold voltage     

BiCMOS logic testing

With the anticipated growth of BiCMOS technology for high-performance ASIC design, the issue of testing takes on great significance. This paper addresses the testing of BiCMOS logic circuits. Since many different implementations of BiCMOS gates have been proposed, four representative ones are studied. The adequacy of stuck-at, quiescent current, and delay testing are examined based on circuit level faults. It is demonstrated that a large portion of the defects cannot be detected by common stuck-at or quiescent current tests since they manifest themselves as delay faults. By using the results presented, the test methodologies and the logic families can be ranked based on fault coverage. This ranking can then be used to help decide which BiCMOS solution is proper for a given application     

Analytical and numerical analyses of the delay time of BiCMOSstructures

Analytical expressions for the transient response of BiCMOS structures have been derived. The analysis is performed on conventional structures and structures employing short-channel MOSFETs. The equations relate the delay time to key device and technology parameters. In deriving the time response, the two basic conduction regions (linear and saturation) for the MOSFET have been considered. A numerical algorithm for solving for the delay time of BiCMOS structures taking into account high-level injection effects, base resistance, doping-dependent mobilities, and bandgap narrowing is presented. A figure of merit for the speed is derived and scaling the supply voltage is considered     

基于0．5μmCMOS工艺的一款新型BiCMOS集成运算放大器设计

为了提高运算放大器的驱动能力,依据现有CMOS集成电路生产线,介绍一款新型BiCMOS集成运算放大电路设计,探讨BiCMOS工艺的特点。在s_Edit中进行“BiCMOS运放设计”电路设计,并对其电路各个器件参数进行调整,包括M0s器件的宽长比和电客电阻的值。完成电路设计后,在Tspice中进行电路的瞬态仿真,插入CMOS,PNP和NPN的工艺库,对电路所需的电源电压和输入信号幅度和频率进行设定调整,最终在W—Edit输出波形图。在MCNC0．5μm工艺平台上完成由MOs、双极型晶体管和电容构成的运算放大器版图设计。根据设计的版图,设计出BiCMOS相应的工艺流程,并提取各光刻工艺的掩模版。     

Low-voltage dynamic BiCMOS CLA circuit with carry skip using novelfull-swing logic

This paper presents novel low-voltage dynamic BiCMOS logic gates and an improved carry look-ahead (CLA) circuit with carry skip using these new dynamic BiCMOS topologies. The well-known “MOS clock feedthrough effect” is used to achieve full swing with substantially reduced low-to-high evaluation delay in the logic gates, thus, resulting in reduced carry propagation/bypass delay in the cascaded CLA array. Simulations at clocking frequency of 100 MHz, using 2-μm BiCMOS process parameters and supply voltage in the range of 2-4 V displays lower gate delay and lower power dissipation compared to other recent dynamic BiCMOS logic topologies. The circuit has no dc power dissipation, race, or charge redistribution problems. An 8-b CLA with 5-b carry skip was achieved in 2.917 ns. This speed is significantly higher than other recent dynamic BiCMOS CLA designs. In addition, the new CLA circuit is more compact compared to previous dynamic BiCMOS CLA designs. A tiny chip was fabricated using the MOSIS Orbit Analog 2-μm V-well CMOS process for the experimental verification of the new low-voltage dynamic BiCMOS topologies     

Fault characterization, testing considerations, and design fortestability of BiCMOS logic circuits

The results of a simulation-based fault characterization study of BiCMOS logic circuits are given. Based on the fault characterization results, the authors have studied different techniques for testing BiCMOS logic circuits. The effectiveness of stuck-at fault testing, stuck-open fault testing, delay fault testing, and current testing in achieving a high level of defect coverage is studied. A novel BiCMOS circuit structure that improves the testability of BiCMOS digital circuits is presented     

0.13μm BiCMOS低压差线性稳压器

设计了一种0.13μm BiCMOS低压差线性稳压器(LDO),包括BiCMOS误差放大器、带软启动的BiCMOS带隙基准源、"套筒式"共源-共栅补偿电路等。为了改善线性瞬态响应性能,在BiCMOS误差放大器的前级设置了动态电流偏置电路。由于所设计的BiCMOS带隙基准源对温度的敏感性较小,故能为LDO提供高精度的基准电压。对所设计的LDO进行了工艺流片。流片测试结果表明,该LDO可提供60 mA的输出电流且最小压差只有100 mV。测试同时验证了所设计LDO的负载和瞬态响应都得到改善:负载调整率为0.054 mV/mA,线性调整率为0.014%,而芯片面积约为0.094 mm2,因此特别适用于高精度、便携式片上电源系统。     

Impact of on-chip interconnect frequency-dependent R(f)L(f) on digital and RF design

On-chip global interconnect exhibits clear frequency dependence in both resistance (R) and inductance ( L). In this paper, its impact on modern digital and radio frequency (RF) circuit design is examined. First, a physical and compact ladder circuit model is developed to capture this behavior, which only employs frequency independent R and L elements, and thus, supports transient analysis. Using this new model we demonstrate that the use of dc values for R and L is sufficient for timing analysis (i.e., 50% delay and slew rate) in digital designs. However, RL frequency dependence is critical for the analysis of signal integrity, shield line insertion, power supply stability, and RF inductor performance.     

Bootstrapped full-swing BiCMOS/BiNMOS logic circuits for 1.2-3.3 Vsupply voltage regime

Novel full-swing BiCMOS/BiNMOS logic circuits using bootstrapping in the pull-up section for low supply voltage down to 1 V are reported. These circuit configurations use noncomplementary BiCMOS technology. Simulations have shown that they outperform other BiCMOS circuits at low supply voltage using 0.35 μm BiCMOS process. The delay and power dissipation of several NAND configurations have been compared. The new circuits offer delay reduction between 40 and 66% over CMOS in the range 1.2-3.3 V supply voltage. The minimum fanout at which the new circuits outperform CMOS gate is 5, which is lower than that of other gates particularly for sub-2.5 V operation