A clock generator circuit for a high-speed high-resolution pipelined A/D converter is presented.The circuit is realized by a delay locked loop(DLL),and a new differential structure is used to improve the precision of the charge pump.Meanwhile,a dynamic logic phase detector and a three transistor NAND logic circuit are proposed to reduce the output jitter by improving the steepness of the clock transition.The proposed circuit,designed by SM1C 0.18μm 3.3 V CMOS technology,is used as a clock generator for a 14 bit 100 MS/s pipelined ADC.The simulation results have shown that the duty cycle ranged from 10%to 90%and can be adjusted.The average duty cycle error is less than 1%.The lock-time is only 13 clock cycles.The active area is 0.05 mm2 and power consumption is less than 15 mW.
A novel fully differential high speed high resolution low offset CMOS dynamic comparator has been implemented in the SMIC 0.18μm process used for a sample-and-hold amplifier(SHA)-less pipelined analogto-digital converters(ADC). Based on the analysis and optimization between delay time and offset, an enhanced reset architecture with transmission gate was introduced to speed up the comparison and reset procedure. Four inputs with two cross coupled differential pairs, reconstituted bias circuit for tail current transistor and common centroid layouts make the comparator more robust against mismatch and process variations. The simulation results demonstrate that the proposed design achieves 1mV sensitivity at 2.2GHz sampling rate with a power consumption of 510 W, while the mean offset voltage is equal to 10.244 mV.
This paper presents a 10-bit 100-MSample/s analog-to-digital（A/D） converter with pipelined folding architecture.The linearity is improved by using an offset cancellation technique and a resistive averaging interpolation network.Cascading alleviates the wide bandwidth requirement of the folding amplifier and distributed interstage track/hold amplifiers are used to realize the pipeline technique for obtaining high resolution.In SMIC 0.18μm CMOS,the A/D converter is measured as follows:the peak integral nonlinearity and differential nonlinearity are±0.48 LSB and±0.33 LSB,respectively.Input range is 1.0 VP-P with a 2.29 mm2 active area.At 20 MHz input @ 100 MHz sample clock,9.59 effective number of bits,59.5 dB of the signal-to-noise-and-distortion ratio and 82.49 dB of the spurious-free dynamic range are achieved.The dissipation power is only 95 mW with a 1.8 V power supply.
Based on the 0.6μm BCDMOS process a hysteretic-current-control mode white light LED driver with high accuracy and efficiency is presented.The driver can work with a 6-40 V power supply,the maximum output current is up to 1.0 A,the maximum switching frequency is up to 1 MHz,the output current error is less than±5%,and the efficiency is greater than 80%.The circuit details of the high-side-current sensor and high-speed comparator,which greatly affect the accuracy of the whole driver,are emphasized.Then,the simulation and test results of this work are presented.
A new design technique for merging the front-end sample-and-hold amplifier(SHA) into the first multiplying digital-to-analog converter(MDAC) is presented.For reducing the aperture error in the first stage of the pipelined ADC,a symmetrical structure is used in a flash ADC and MDAC.Furthermore,a variable resistor tuning network is placed at the flash input to compensate for different cutoff frequencies of the input impedances of the flash and MDAC.The circuit also has a clear clock phase in the MDAC and separate sampling capacitors in the flash ADC to eliminate the nonlinear charge kickback to the input signal.The proposed circuit,designed using ASMC 0.35-μm BiCMOS technology,occupies an area of 1.4 x 9 mm^2 and is used as the front-end stage in a 14-bit 125-MS/s pipelined ADC.After the trim circuit is enabled,the measured signal-to-noise ratio is improved from 71.5 to 73.6 dB and the spurious free dynamic range is improved from 80.5 to 83.1 dB with a 30.8 MHz input. The maximum input frequency is up to 150 MHz without steep performance degradations.
As the front-end preamplifiers in optical receivers, transimpedance amplifiers(TIAs) are commonly required to have a high gain and low input noise to amplify the weak and susceptible input signal. At the same time, the TIAs should possess a wide dynamic range(DR) to prevent the circuit from becoming saturated by high input currents. Based on the above, this paper presents a CMOS transimpedance amplifier with high gain and a wide DR for 2.5 Gbit/s communications. The TIA proposed consists of a three-stage cascade pull push inverter,an automatic gain control circuit, and a shunt transistor controlled by the resistive divider. The inductive-series peaking technique is used to further extend the bandwidth. The TIA proposed displays a maximum transimpedance gain of 88.3 dB with the –3 dB bandwidth of 1.8 GHz, exhibits an input current dynamic range from 100 nA to10 mA. The output voltage noise is less than 48.23 nV/p Hz within the –3 dB bandwidth. The circuit is fabricated using an SMIC 0.18 m 1P6M RFCMOS process and dissipates a dc power of 9.4 mW with 1.8 V supply voltage.
A programmable high precision multiplying DAC(MDAC) is proposed. The MDAC incorporates a frequency-current converter(FCC) to adjust the power versus sampling rate and a programmable operational amplifier(POTA) to achieve the tradeoff between resolution and power of the MDAC, which makes the MDAC suitable for a 12 bit SHA-less pipelined ADC. The prototype of the proposed pipelined ADC is implemented in an SMIC CMOS 0.18 m 1P6M process. Experimental results demonstrate that power of the proposed ADC varies from 15.4 mW(10 MHz) to 63 mW(100 MHz) while maintaining an SNDR of 60.5 to 63 dB at all sampling rates.The differential nonlinearity and integral nonlinearity without any calibration are no more than 2.2/–1 LSB and1.6/–1.9 LSB, respectively.
On-chip interconnect buses consume tens of percents of dynamic power in a nanometer scale integrated circuit and they will consume more power with the rapid scaling down of technology size and continuously rising clock frequency, therefore it is meaningful to lower the interconnecting bus power in design. In this paper, a simple yet accurate interconnect parasitic capacitance model is presented first and then, based on this model, a novel interconnecting bus optimization method is proposed. Wire spacing is a process for spacing wires for minimum dynamic power, while wire ordering is a process that searches for wire orders that maximally enhance it. The method, i.e., combining wire spacing with wire ordering, focuses on bus dynamic power optimization with a consideration of bus performance requirements. The optimization method is verified based on various nanometer technology parameters, showing that with 50% slack of routing space, 25.71% and 32.65% of power can be saved on average by the proposed optimization method for a global bus and an intermediate bus, respectively, under a 65-nm technology node, compared with 21.78% and 27.68% of power saved on average by uniform spacing technology. The proposed method is especially suitable for computer-aided design of nanometer scale on-chip buses.
