Analog Devices,inc.

Analog Devices International Unlimited Company

Haiyang Zhu

Ronald Alan Kapusta

Wenhua William Yang

David Paul Foley

Nathan T Egan

Colin Gerard Lyden

Hajime Shibata

Donald W Paterson

Sharvil Pradeep Patil

Asha Ganesan

Continuous-time (CT) analog-to-digital converters (ADCs) implementing digital correction of digital-to-analog converter (DAC) errors are disclosed. In a CT pipeline stage of a CT ADC, a CT analog input signal is sent to two different paths. A first path (a 'feedforward' path) includes a cascade of a sub-ADC and a sub-DAC. A second path (a “forward” path) includes an analog delay circuit to align the delays of the input signal in the feedforward and forward paths. A combiner subtracts the output of the analog delay of the forward path from the output of the sub-DAC in the feedforward path to generate a residue signal. Devices and methods disclosed herein are based on recognition that, if the errors introduced by the sub-DAC are known, they can be corrected in the digital domain during reconstruction, achieving superior NSD and distortion performance compared to conventional approaches.

Digital correction of digital-to-analog converter errors in continuous-time analog-to-digital converters

In an example embodiment, a circuit is provided that includes a current source with a calibrated trim circuit whose output current varies with transconductance of the current source, and tracks a current mismatch between the current source and another current source under varying bias currents and temperatures. The trim circuit may include at least one calibration digital to analog converter (CAL DAC), which may be driven by a bias circuit generating current proportional to the transconductance of the current source. In an example embodiment, the trim circuit may include at least two CAL DACs, whose output current may vary with bias current only, and with bias current and temperature. A method to calibrate the CAL DACs includes varying calibration settings of the CAL DACs under different bias currents until the output current of the trim circuit substantially accurately tracks the current mismatch under disparate bias currents and temperatures.

Current source calibration tracking temperature and bias current

A slew rate booster, switchably enabled selector, or other arrangement may be included in a cascode amplifier to keep the current buffer/common gate transistor and the input/common source transistor saturated as the voltage at the source of the current buffer transistor drops during a transient input voltage spike at the gate of the input transistor. In some instances a higher potential may be supplied to a gate of the current buffer transistor during an initial phase of the settling period than during a second phase of the settling period when a lower potential may be applied. Other techniques may be used in different embodiments. Devices and methods are provided.

Cascode amplifier

An architecture of an integrated circuit allows for the canceling of noise sampled on a capacitor in the integrated circuit, after an input signal has already been sampled. Thermal noise correlated with an arbitrary input signal may be canceled after selectively controlling a plurality of switching devices during a sequence of clock phases. An auxiliary capacitor may be used to store a voltage equal to the thermal noise and enable the cancellation of the thermal noise from the sampled signal in conjunction with a noise cancellation unit.

Noise cancellation system and method for amplifiers

The invention is directed to a protection circuit for protecting IC chips against ESD. An ESD protection circuit for an integrated circuit chip may comprise an isolated NMOS transistor, which may comprise an isolation region isolating a backgate from a substrate, and a first and second doped regions and a gate formed on the backgate. The ESD protection circuit may further comprise a first terminal to connect the isolation region to a first electrical node, and a second terminal to connect the second doped region to a second electrical node. The first electrical node may have a higher voltage level than the second electrical node, and the gate and backgate may be coupled to the second terminal.

System and method for isolated NMOS-based ESD clamp cell

The present invention relates to a semiconductor device including a substrate layer, a metal-oxide-semiconductor field-effect transistor (MOSFET), a backgate region, an isolation layer and a diode. The MOSFET includes a gate region, a source region and a drain region. The source and drain regions are embedded in the backgate region, which includes a voltage input terminal. The isolation layer is located between the backgate region and the substrate layer and has a doping type opposite that of the backgate region. The diode includes a first terminal connected to the isolation layer and a second terminal coupled to an isolation voltage source.

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Wilmington, MA, United States of America

Haiyang Zhu