US 9,411,987 B2 · Low noise and low power passive sampling network for a switched-capacitor ADC with a slow reference generator

Abstract

Certain aspects of the present disclosure provide various sampling networks for switched-capacitor integrators, which may be used in switched-capacitor analog-to-digital converters (ADCs). Rather than having both an input sampling capacitor and a reference sampling capacitor, certain aspects of the present disclosure use a shared sampling capacitor for the reference voltage and the input voltage, thereby reducing ADC input-referred noise, decreasing op amp area and power, and avoiding anti-aliasing filter insertion loss. Furthermore, by sampling the reference voltage during the sampling phase and sampling the input voltage during the integration phase using the shared sampling capacitor, a high-bandwidth reference buffer need not be used for the reference voltage.

Claims31

Dependent claims

A switched-capacitor integrator, comprising:

an amplifier having first and second output nodes and first and second input nodes;
a first integration capacitor coupled between the first output node and the first input node;
a second integration capacitor coupled between the second output node and the second input node;
first and second sampling capacitors, each having a first terminal and a second terminal;
a first set of switches configured to
connect reference voltage nodes with the first terminals of the first and second sampling capacitors during a sampling phase of the integrator;
and
short the second terminals of the first and second sampling capacitors together during the sampling phase;
and
a second set of switches configured, during an integration phase of the integrator, to connect:
input voltage nodes with the first terminals of the first and second sampling capacitors;
and
the first and second input nodes of the amplifier with the second terminals of the first and second sampling capacitors, wherein the first set of switches is open during the integration phase and wherein the second set of switches is open during the sampling phase.

10 more elements

A switched-capacitor integrator, comprising:

an amplifier having first and second output nodes and first and second input nodes;
a first integration capacitor coupled between the first output node and the first input node;
a second integration capacitor coupled between the second output node and the second input node;
first and second sampling capacitors, each having a first terminal and a second terminal;
a first set of switches configured to connect reference voltage nodes with the first terminals of the first and second sampling capacitors during reference sampling phases of the integrator;
and
a second set of switches configured, during integration phases of the integrator, to connect:
the second terminals of the first and second sampling capacitors with the first and second input nodes of the amplifier;
and
the first terminals of the first and second sampling capacitors with outputs of first and second sampling networks, wherein the first set of switches is open during the integration phases, wherein the second set of switches is open during the reference sampling phases, and wherein each of the first and second sampling networks comprises:
a first input capacitor having first and second terminals;
a second input capacitor having first and second terminals;
a third set of switches configured to selectively connect an input node of the sampling network with the first terminal of the first input capacitor;
a fourth set of switches configured to connect an output node of the sampling network with the second terminal of the second input capacitor during a first set of the integration phases;
a fifth set of switches configured to selectively connect the input node of the sampling network with the first terminal of the second input capacitor;
and
a sixth set of switches configured to connect the output node of the sampling network with the second terminal of the first input capacitor during a second set of the integration phases.

14 more elements

Dependencies are inferred from the claim text.

Low noise and low power passive sampling network for a switched-capacitor ADC with a slow reference generator

Life of this patent

Low noise and low power passive sampling network for a switched-capacitor ADC with a slow reference generator

Life of this patent

Abstract

Claims31