Sozopol 2009 Dynamic Approaches to Mixed Signal Design

Sozopol, 2009 Dynamic Approaches to Mixed – Signal Design Angel Nikolaev Popov

Sozopol, 2009 Introduction “It is important to design circuits with both a circuits and a systems perspective in mind” Jan Rabaey POWER DIE SPEED ACCURACY I/O PINS NOISE “Everything should be made as simple as possible – but no simpler” Einstein

Sozopol, 2009 Noise Immunity – Dynamic Hysteresis “The best way to have a good idea is to have a lot of ideas”, Linus Pauling POWER DIE SPEED ACCURACY I/O PINS NOISE The Schmitt Trigger, as defined by its inventor: A bistable positive feedback circuit, realizable with vacuum tubes or even fluidic components, but now usually solid-state electronics, which features a selected or adjustable hysteresis band separating initiation of "on" and "off" or "1" and "0" (1934)

Sozopol, 2009 A. Getting the idea

Sozopol, 2009 Inverting Schmitt trigger and its signals

Sozopol, 2009 Synthesis of a Schmitt trigger with dynamic hysteresis

Sozopol, 2009 B. Circuit based on two Op. Amps

Sozopol, 2009 C. CMOS circuits CMOS Schmitt trigger proposed in [21 -W. Sansen] and its symmetric version

Sozopol, 2009 CMOS Schmitt trigger

Sozopol, 2009 Simulated waveforms showing the behavior of a comparator with noise immunity of 1 V when the amplitude of the noise is less than 1 V Simulated waveforms showing the behavior of a comparator with noise immunity of 1 V when the amplitude of the noise is bigger than 1 V

Sozopol, 2009 Experimental result demonstrating the expected one threshold behavior

Sozopol, 2009 D. BJT circuit ST circuit with a capacitor inserted in the PF loop

BJT comparator

Sozopol, 2009 Waveforms demonstrating the operation of the BJT comparator

Sozopol, 2009 E. Aapplication – Analog-to-Digital Converter Design Parallel resistorless ADC CMOS inverter used as comparator

Sozopol, 2009 E 1. Threshold Voltage Determination Inverter threshold voltage VTHI as a function of transistor area ratio k

Sozopol, 2009 E 2. Transfer characteristics Threshold voltage grid for a 3 -bit ADC with two cascaded inverters Threshold voltage grid for a 3 -bit ADC with an inverter and a dynamic hysteresis Schmitt trigger

Sozopol, 2009 E 3. Dynamic behavior ADC delays in thermometer code as a function of k for an inverter booster (dashed) and. a Schmitt trigger booster (solid)

TOWARDS SYSTEM-ON-A-CHIP DESIGN OF HIGH-SPEED DATA ACQUISITION SYSTEMS Angel Popov Technical University of Sofia e-mail: anp@tu-sofia. acad. bg “The principal applications of any sufficiently new and innovative technology always have been and will continue to be applications created by that new technology” “The Futility of Predicting Applications” Herbert Kroemer, 2000 Nobel laureate …In other words, if we are going to make something truly new, we won’t know what to do with it until after we’ve brought it into being…

Sozopol, 2009 Power Consumption – Current Mode Switching POWER SPEED ACCURACY “A good scientist is a person with original ideas. A good engineer is a person who makes a design that works as few DIE original ideas as possible” J. Poole I/O PINS NOISE

Sozopol, 2009 A. Classic Emitter-Coupled Multivibrator

Sozopol, 2009 C. Frequency control by switching current IFC

Sozopol, 2009 D. VCO/CCO schematics

Sozopol, 2009 Voltage control of the CCO

Sozopol, 2009 AN ECL CIRCUIT WITH SYMMETRICAL CAPACITANCECOUPLED ACTIVE PULL-DOWN EMITTER FOLLOWER STAGES

Sozopol, 2009 Accuracy – Precise Divide-by-Two “A design is what the designer has when time and money run out” J. Poole POWER DIE SPEED ACCURACY I/O PINS NOISE

Sozopol, 2009 A. Two-capacitor DAC background

Sozopol, 2009 B. Implementation of precise division by two Proposed schematics for precise division by two

Sozopol, 2009 C. RESULTS

Sozopol, 2009 CONCLUSIONS ”There’s Plenty of Room at the Bottom” R. Feynman A look into the future should prove the sentence: The most “foolish” ideas at the highest level need respective support from the bottom level.

Thank you for your attention!