A novel low-offset dynamic comparator for high-speed low-voltage analog-to-digital converters （ADCs） has been proposed.In the proposed comparator,a CMOS switch takes the place of the dynamic current sources in the differential comparator,which allows the differential input transistors still to operate in the saturation region at the comparing time.This gives the proposed comparator a low offset as the differential comparator while tolerating a sub-1-V supply voltage.Additionally,it also features a larger input swing,less sensitivity to common mode voltage,and a simple relationship between the input and reference voltage.This proposed comparator with two traditional comparators has been realized by SMIC 0.13μm CMOS technology.The contrast experimental results verify these advantages over conventional comparators.It has been used in a 12-bit 100-MS/s pipeline ADC.
An 8-b 100-MS/s pipelined analog-to-digital converter（ADC） is presented.Without the dedicated sample-and -hold amplifier（SHA）,it achieves figure-of-merit and area 21%and 12%less than the conventional ADC with the dedicated SHA,respectively.The closed-loop bandwidth of op amps in multiplying DAC is modeled,providing guidelines for power optimization.The theory is well supported by transistor level simulations.A 0.18-μm 1P6M CMOS process was used to integrate the ADCs,and the measured results show that the effective number of bits is 7.43 bit and 6.94 bit for 1-MHz and 80-MHz input signal,respectively,at 100 MS/s.The power dissipation is 23.4 mW including voltage/current reference at 1.8-V supply,and FoM is 0.85 pJ/step.The ADC core area is 0.53 mm^2.INL is -0.99 to 0.76 LSB,and DNL is -0.49 to 0.56 LSB.
A fourth-order switched-capacitor bandpass ∑△ modulator is presented for digital intermediatefrequency （IF） receivers. The circuit operates at a sampling frequency of 100 MHz. The transfer function of the resonator considering nonidealities of the operational amplifier is proposed so as to optimize the performance of resonators. The modulator is implemented in a 0.13-μm standard CMOS process. The measurement shows that the signal-to-noise-and-distortion ratio and dynamic range achieve 68 dB and 75 dB, respectively, over a bandwidth of 200 kHz centered at 25 MHz, and the power dissipation is 8.2 mW at a 1.2 V supply.
A 10-bit 30-MS/s pipelined analog-to-digital converter（ADC） is presented.For the sake of lower power and area,the pipelined stages are scaled in current and area,and op amps are shared between the successive stages. The ADC is realized in the 0.13-μm 1-poly 8-copper mixed signal CMOS process operating at 1.2-V supply voltage. Design approaches are discussed to overcome the challenges associated with this choice of process and supply voltage, such as limited dynamic range,poor analog characteristic devices,the limited linearity of analog switches and the embedded sub-1-V bandgap voltage reference.Measured results show that the ADC achieves 55.1-dB signal-to-noise and distortion ratio,67.5-dB spurious free dynamic range and 19.2-mW power under conditions of 30 MSPS and 10.7- MHz input signal.The FoM is 0.33 pJ/step.The peak integral and differential nonlinearities are 1.13 LSB and 0.77 LSB,respectively.The ADC core area is 0.94 mm^2.
