Analog Devices,inc.

Other

Analog Devices Global Unlimited Company

Lawrence A Singer

Siddharth Devarajan

Todd L Brooks

Daniel F Kelly

Harvey Weinberg

Erik D Barnes

Iuri Mehr

Todd L Books

Martin Clara

Hajime Shibata

Wenhua William Yang

Steven J Decker

Gabriele Manganaro

David H Robertson

Ronald A Kapusta, Jr

Yunzhi Dong

Matthew Louis Courcy

Frank M Murden

Gil Engel

David Nelson Alldred

Christopher Daniel Dillon

Sharvil Pradeep Patil

Stephen Robert Kosic

Jennifer Lloyd

Prawal Man Shrestha

William George John Schofield

Richard Schreier

Pingli Huang

The trend in wireless communication receivers is to capture more and more bandwidth to support higher throughput, and to directly sample the radio frequency (RF) signal to enable re-configurability and lower cost. Other applications like instrumentation also demand the ability to digitize wide bandwidth RF signals. These applications benefit from input circuitry which can perform well with high speed, wide bandwidth RF signals. An input buffer and bootstrapped switch are designed to service such applications, and can be implemented in 28 nm complementary metal-oxide (CMOS) technology.

Input buffer

Optical systems can emit train(s) of light pulses onto objects to derive a distance between the light source and the object. Achieving meter or centimeter resolution may require very short light pulses. It is not trivial to design a circuit that can generate narrow current pulses for driving a diode that emits the light pulses. An improved driver circuit has a pre-charge path comprising one or more inductive elements and a fire path comprising the diode. Switches in the driver circuit are controlled with predefined states during different intervals to pre-charge current in the one or more inductive elements prior to flowing current through the fire path to pulse the diode.

Pulsed laser diode driver

Bootstrapped switching circuit

Residue generation systems for use in continuous-time and hybrid ADCs are described. An exemplary system includes a filter, e.g. a FIR filter, for generating a filtered analog output based on an analog input, a quantizer for generating a digital input to a feedforward DAC based on the filtered analog output generated by the filter, a feedforward DAC for generating a feedforward path analog output based on the digital input generated by the quantizer, and a subtractor for generating a residue signal based on the feedforward path analog output. Providing a filter that filters the analog input before it is quantized advantageously allows blockers to be attenuated before they are sampled and aliased by the quantizer. At least some of the residue generation systems described herein may be implemented with relatively small design and power dissipation overheads.

Blocker tolerance in continuous-time residue generating analog-to-digital converters

An apparatus and method for implementing a bootstrapped switching circuit having improved (i.e. faster) turn-on time is provided. In an embodiment, an inner switching loop is implemented in a bootstrapped switching circuit where the inner switching loop is configured to turn on an input switch in the bootstrapped drive circuit independent of the drive circuit output. The embodiment decouples the inner switching loop circuitry from the output drive circuit of the bootstrapped switching circuit, which typically has a larger load capacitance than the inner switching loop. This allows the inner switching loop to turn on the input switch in the bootstrapped switching circuit faster and decreases the turn-on time of the bootstrapped switching circuit.

Bootstrapped switching circuit with fast turn-on

A time-interleaved analog-to-digital converter (ADC) uses M sub-analog-to-digital converters (sub-ADCs) to, according to a sequence, sample an analog input signal to produce digital outputs. When the M sub-ADCs are interleaved, the digital outputs exhibit mismatch errors between the M sub-ADCs due to mismatches between the sub-ADCs. A more second order subtle effect is that the mismatch error for a particular digital output from a particular ADC, due to internal coupling or other such interaction and effects between the M sub-ADCs, can vary depending on which sub-ADC(s) were used before and/or after the particular sub-ADC. If M sub-ADCs are time-interleaved randomly, the mismatches between the M sub-ADCs become a function of the sub-ADC selection pattern in the sequence. The present disclosure describes mechanisms for measuring and reducing these order-dependent mismatches to achieve high dynamic range performance in the time-interleaved ADC.

Methods and systems for reducing order-dependent mismatch errors in time-interleaved analog-to-digital converters

The present disclosure provides embodiments of an improved current steering switching element for use in a digital to analog (DAC) converter. Typically, each current steering switching element in the DAC converter provides a varying set of currents for converting a digital input signal. Generally, the switches and drivers in the current steering switching elements are scaled down proportionally to the current being provided by the current steering switching element according to a ratio as less and less current is being driven by the switching element in order to overcome timing errors. However, device sizes are limited by the production process. When a switch is not scaled proportionally to the current, settling timing errors are present and affects the performance of the DAC. The improved current steering switching element alleviates this issue of timing errors by replacing the single switch with two complementary current steering switches.

Complementary switches in current switching digital to analog converters

In one example embodiment, a programmable capacitor array is provided for low distortion and minimizing linearity degradation of an input (Vin) by utilizing control circuitry to switch on and off an array of MOSFET switches. The control circuitry turns on a MOSFET to load a capacitance on Vin and turns off the MOSFET to remove the capacitance from Vin in response to a Din control signal. When the intention is to load Vin with the capacitance, the MOSFET is left on continuously. When the intention is to remove or unload the capacitance from Vin, the MOSFET is primarily turned off, however, the MOSFET is still periodically turned on with appropriate voltage levels in response to a clock signal for periods of time when the loading of the capacitance on Vin is tolerable to the system, thereby ensuring minimal linearity degradation of Vin due to the programmable capacitor array system.

Low-distortion programmable capacitor array

An example apparatus, system, and method for sampling in an interleaved sampling circuit having multiple channels. In an embodiment, an input clock is used to synchronize the transitions of sampling clocks from a first to second voltage level, relative to one another. The sampling clocks are input to a sampling circuit. The input clock switches a common switch that pulls each sampling clock to the second voltage level through a common path on input clock transitions from a first to a second clock state. The transition from the first to a second voltage level of each sampling clock triggers a sample taken on one of the channels. The first voltage level may be boosted to drive switches on in the sampling circuit. Synchronizing transitions of the outputs through the common switch and common path reduces timing mismatch between the sampling clocks controlling the channels.

Apparatus and method for reducing sampling circuit timing mismatch

A programmable clock booster system including a clock booster circuit including at least one boost capacitor connected between a first node and a second node for sampling an input voltage in a first phase and applying a boosting voltage to said second node during a second phase, and a programmable capacitor circuit connected to said first node for providing a programmable boosted voltage on said first node during said second phase.

Programmable clock booster system

Two or more buffers may configured and arranged such that a quiescent current that flows through and biases a first buffer also flows through and biases a second buffer. The first and second buffers may, for example, be source followers used as reference buffers that drive inputs of a switched-capacitor circuit.

Stacked buffers

A differential two-stage Miller compensated amplifier system with capacitive level shifting includes a first stage differential transconductance amplifier including first and second output nodes and an output common mode voltage, a second stage differential transconductance amplifier including non-inverting and inverting inputs and outputs and an input common mode voltage, and a level shifting capacitor circuit coupled between the first and second output nodes and the non-inverting and inverting inputs for level shifting between the output common mode voltage of the first stage and the input common mode voltage of the second stage.

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Wenham, MA, United States of America

Lawrence A Singer