Analog Devices,inc.

Scott Gregory Bardsley

Franklin Marshall Murden, Ii

Peter Derounian

Ahmed Mohamed Abdelatty Ali

Michael Ray Elliott

Ravi Kishore Kummaraguntla

Eric John Siragusa

Huseyin Dinc

Ralph David Moore, Jr

Carroll Clifton Speir

James C Camp

Christopher Daniel Dillon

Bryan Scott Puckett

Matthew D McShea

Andrew Stacy Morgan

Baeton Charles Rigsbee

An example boosted switch driver circuit includes two branches. The first branch includes a first transistor. The second branch includes a second transistor and a level shifter circuit. One of the transistors is an N-type transistor and the other one is a P-type transistor. The circuit is configured to split an input clock signal between the first branch and the second branch, so that a portion of the input clock signal split to the first branch is provided to the first transistor, and a portion of the input clock signal split to the second branch is level-shifted by the level shifter circuit to generate a level-shifted input clock signal and the level-shifted input clock signal is provided to the second transistor. The circuit is further configured to combine an output of the first transistor and an output of the second transistor to generate an output clock signal.

Boosted switch drivers for high-speed signal switching

In pipelined analog-to-digital converters (ADCs), a passive switched capacitor (PSWC) circuit can be used in a multiplying analog-to-digital converter (MDAC), which generates an analog output being fed to a subsequent stage. Complementary analog input signals are sampled respectively onto first and second capacitors, which are stacked to provide gain. The first capacitor is positioned between a first input switch and an output node of the PSWC circuit, and the second capacitor is positioned between the second input switch and a digital-to-analog converter (DAC) output. The topology advantageously isolates common modes of the complementary analog input signals, the DAC output, and the output of the PSWC circuit. As a result, the topology offers more degrees of freedom in the overall circuit design when stages having the MDAC are cascaded, resulting in pipelined ADCs with a more elegant design with lower noise and lower power consumption.

Passive switched capacitor circuit for sampling and amplification

A clock shifter circuit may receive a input clock in a first voltage domain and may generate a level-shifted output clock in a second voltage domain. The circuit may include a cross-coupled pair of transistor switches and a pair of capacitors. Each switch may have a drain coupled to one of the capacitors, a source coupled to a circuit supply voltage, and a gate coupled to the other capacitor. One capacitor may receive a true input clock version, while the other may receive a complement version. Each capacitor, in an alternating manner, may activate an opposing transistor switch to charge its capacitor during an active phase of its respective input clock. The circuit may generate the output clock from an output node connected between one of the transistor switches and its capacitor. The output clock may drive a load directly coupled to the output node.

System for a clock shifter circuit

Circuits and methods are introduced to allow for timing relationship between a clock signal and a synchronization signal to be observed. The observations may include observing the timing relationship between a capture edge of the clock signal and a transition of the synchronization signal. Based on the observations the timing of the synchronization signal transition may be adjusted. Observing the timing relationship may include providing a delayed synchronization signal and a delayed clock signal. The delayed synchronization signal may provide what happens before the capture edge of the clock signal. The delayed clock signal may provide what happens after the capture edge of the clock signal.

Clock signal synchronization

One embodiment relates to an apparatus configured to cancel charge injected on a node of a differential pair of nodes. A dummy circuit element can inject charge on an inverted node to cancel charge injected on a non-inverted node by a switch when the switch is switched off. In addition, another dummy circuit element can inject charge on the non-inverted node to cancel charge injected on the inverted node by another switch when the other switch is switched off. These dummy circuits elements can be cross-coupled.

Differential charge reduction

An analog-to-digital converter includes a plurality of sequentially cascaded stages, each stage including an amplifier and four copies of a circuit block including a flash and capacitors, in which the four copies of the circuit block operate interleavingly in a respective sample mode, pre-gain mode, gain mode, and reset mode of the circuit block, the copies of the circuit block in the sample mode, pre-gain mode, and reset mode are decoupled from the amplifier, and the copy of the circuit block in the gain mode is coupled to the amplifier to produce an output for a next following stage.

Pipelined analog-to-digital converter

Apparatus and methods for pipelined analog-to-digital conversion are disclosed. In some embodiments, a pipeline analog-to-digital converter includes a plurality of multiplying digital-to-analog converter (MDAC) stages coupled in cascade. At least one of the MDAC stages includes two or more flash ADCs connected in parallel, operating alternately to generate digital signals from an analog input voltage. In one embodiment, the flash ADCs provide the digital signals in an alternating manner to a capacitor block that receives a delayed analog input voltage. In another embodiment, the at least one MDAC may include two or more capacitor blocks, each of which is associated with a respective one of the flash ADCs, forming two or more sets of a flash ADC and a capacitor block. In yet another embodiment, the at least one MDAC also include three or more capacitor blocks, each of which can be randomly selected for one of the flash ADCs.

Apparatus and method for pipelined analog to digital conversion

Apparatus and methods for pipelined analog-to-digital conversion are disclosed. In some embodiments, a pipelined analog-to-digital converter includes a control and correction circuit; and a plurality of MDAC stages. At least one of the MDAC stages includes: an MDAC input to receive an analog input voltage; and a dual latch flash ADC comprising one or more dual latch comparators. At least one of the dual latch comparators includes: a pre-amplifier having an input coupled to the MDAC input, and an output; a demultiplexer having an input coupled to the output of the pre-amplifier, a first output, and a second output; a first latch having an input coupled to the first output of the demultiplexer, wherein the first latch may generate a first digital signal; and a second latch having an input coupled to the second output of the demultiplexer, wherein the second latch may generate a second digital signal.

Operational amplifier embodiments are provided to enhance amplifier parameters such as bandwidth, stability, and headroom. In an amplifier embodiment, transistor followers are arranged with first and second differential pairs to facilitate selective positioning of first and second transfer function poles to enhance bandwidth and resistors and inductors are arranged to facilitate selective positioning of complex third transfer function poles to enhance phase margin. In another amplifier embodiment, the transistor followers are arranged to reduce headroom limitations to thereby enhance the voltage swing of output signals.

Operational amplifiers with enhanced parameters

A device and method for correlation-based background calibration of pipelined converters with a reduced power penalty. A pipelined analog-to-digital converter (ADC) utilizes a random or pseudorandom signal to reduce the quantization error of subconverting stages. Stages within the ADC comprise an injection circuit having a plurality of capacitive branches in parallel. Less than all of the branches can function during a given clock cycle of the ADC. This allows a subconverting stage within the ADC to be accurately trimmed before operation using a large amplitude signal. At the same time, the capability to inject smaller amplitude random or pseudorandom signals into the subconverting stage during operation is maintained, saving valuable dynamic range and power. The various capacitive branches are cycled through either randomly or in sequence such that the quantizer manifests the same average gain error over time for which the quantizer was initially trimmed.

Correlation-based background calibration of pipelined converters with reduced power penalty

Signal converter system embodiments are provided to substantially reduce symmetrical and asymmetrical conversion errors. Signal-processing stages of these embodiments may include a signal sampler in addition to successively-arranged signal converters. In system embodiments, injected analog dither signals are initiated in response to a random digital code. They combine with a system's analog input signal and the combined signal is processed down randomly-selected signal-processing paths of the converter system to thereby realize significant improvements in system linearity. Because these linearity improvements are realized by simultaneous processing of the input signal and the injected dither signal, a combined digital code is realized at the system's output. A first portion of this combined digital code corresponds to the analog input signal and a second portion corresponds to the injected analog dither signal. The final system digital code is realized by subtracting out the second portion with a back-end decoder that responds to the random digital code.

Pipelined converter systems with enhanced linearity

Differential amplifiers are provided with a common-mode controller that establishes an amplifier common-mode output level while it also enhances amplifier gain and output impedance. The amplifier includes cascode transistors and the controller includes positive-feedback transistors that respond to an output side of the cascode transistors and negative-feedback transistors that respond to an input side of the cascode transistors. Gain and output impedance are increased by the positive-feedback transistors and the increase is controlled by the negative-feedback transistors. Common-mode level is established by voltages between current and control terminals of the positive-feedback transistors. The differential amplifiers are shown to be especially suited for use in switched-capacitor structures.

Differential amplifiers with enhanced gain and controlled common-mode output level

An improved pipelined analog to digital converter that facilitates calibration for non-linearity errors and a method for obtaining calibration values. The analog to digital converter has a calibration mode in which the output bits for stages in the pipeline can be coupled to output pins of the device. Device pins that are used in normal operating mode to output the most significant bits of the ADC output are used in calibration mode to make available output bits of a pipeline stage being calibrated. A calibration method takes advantage of the outputs of the stages being directly observable to compute calibration values. The output bits of a pipeline stage are monitored as the analog input to the ADC is increased. A change in these bits identifies a subrange boundary. Errors are measured for values immediately above and immediately below each subrange boundary and used to compute correction factors.

Calibration of analog to digital converter by means of multiplexed stages

Methods and apparatus for calibrating one or more signals of an electronic device are provided. Calibration coefficients are stored in a memory, such as a fuse bank, to be applied to correct the one or more signals. A selection multiplexer is provided, the selection multiplexer capable of assigning one of a number of bit weight configurations to the calibration coefficients to set a desired range and resolution for calibration information applied to the one or more signals of the electronic device.

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Gibsonville, NC, United States of America

Scott Gregory Bardsley