To protect security devices such as smart cards against power attacks, we propose a dynamic and differential CMOS logic style. The logic operates with a power consumption independent of both the logic values and the sequence of the data. Consequently, it will not reveal the sensitive data in a device. We have built a set of logic gates and flip-flops needed for cryptographic functions and compared those to Static Complementary CMOS implementations.

A dynamic and differential CMOS logic with signal independent power consumption to withstand differential power analysis on smart cards

A latch-type voltage sense amplifier in 90nm CMOS is designed with a separated input and cross-coupled stage. This separation enables fast operation over a wide common-mode and supply voltage range. With a 1-sigma offset of 8mV, the circuit consumes 92fJ/decision with a 1.2V supply. It has an input equivalent noise of 1.5mV and requires 18ps setup-plus-hold time

/pdf/a-double-tail-latch-type-voltage-sense-amplifier-with-18ps-aluyuprtro.pdf

A Double-Tail Latch-Type Voltage Sense Amplifier with 18ps Setup+Hold Time

A quantitative yield analysis of a latch-type voltage sense amplifier with a high-impedance differential input stage is presented. It investigates the impact of supply voltage, input DC level, transistor sizing, and temperature on the input offset voltage. The input DC level turns out to be most significant. Also, an analytical expression for the sensing delay is derived which shows low sensitivity on the input DC bias voltage. A figure of merit indicates that an input dc level of 0.7 V/sub DD/ is optimal regarding speed and yield. Experimental results in 130-nm CMOS technology confirm that the yield can be significantly improved by lowering the input DC voltage to about 70% of the supply voltage. Thereby, the offset standard deviation decreases from 19 to 8.5 mV without affecting the delay.

Yield and speed optimization of a latch-type voltage sense amplifier

Design and experimental evaluation of a new sense-amplifier-based flip-flop (SAFF) is presented. It was found that the main speed bottleneck of existing SAFF's is the cross-coupled set-reset (SR) latch in the output stage. The new flip-flop uses a new output stage latch topology that significantly reduces delay and improves driving capability. The performance of this flip-flop is verified by measurements on a test chip implemented in 0.18 /spl mu/m effective channel length CMOS. Demonstrated speed places it among the fastest flip-flops used in the state-of-the-art processors. Measurement techniques employed in this work as well as the measurement set-up are discussed in this paper.

/pdf/improved-sense-amplifier-based-flip-flop-design-and-1l8icizbke.pdf

Improved sense-amplifier-based flip-flop: design and measurements

We propose and demonstrate a 20-ps time-to-digital converter (TDC) realized in 90-nm digital CMOS. It is used as a phase/frequency detector and charge pump replacement in an all-digital phase-locked loop for a fully-compliant Global System for Mobile Communications (GSM) transceiver. The TDC core is based on a pseudodifferential digital architecture that makes it insensitive to nMOS and pMOS transistor mismatches. The time conversion resolution is equal to an inverter propagation delay, which is the finest logic-level regenerative timing in CMOS. The TDC is self calibrating with the estimation accuracy better than 1%. It additionally serves as a CMOS process strength estimator for analog circuits in this large system-on-chip. Measured integral nonlinearity is 0.7 least significant bits. The TDC consumes 5.3 mA raw and 1.3 mA with power management from a 1.3-V supply.

1.3 V 20 ps time-to-digital converter for frequency synthesis in 90-nm CMOS

Timing elements, latches and flip-flops, are critical to performance of digital systems, due to tighter timing constraints and low power requirements. Short setup and hold times are essential, but often overlooked. Recently reported flip-flop structures achieved small delay between the latest point of data arrival and output transition. Typical representatives of these structures are sense amplifier-based flip-flop (SAFF), hybrid latch-flip-flop (HLFF) and semi-dynamic flipflop (SDFF). Hybrid flip-flops outperform reported sense amplifier-based designs, because the latter are limited by the output latch implementation. SAFF consists ofthe sense amplifier in the first stage and the RS latch in the second stage.

Sense amplifier-based flip-flop

A flip-flop including a first stage and a second stage. The first stage receives a pair of differential signals to generate a set and reset signal. The complement of the set and reset signal generates output signals Q and {overscore (Q)}′. These signals have rising and falling transistors with the same delays for the Q signal and the {overscore (Q)} signal. The second stage has symmetrical pull-up and pull-down circuits.

Wenyan Jia

Papers

Improved sense-amplifier-based flip-flop: design and measurements

Sense amplifier-based flip-flop

Sense amplifier-based flip-flop with asynchronous set and reset