US 7,479,910 B1 · Capacitive digital-to-analog converter reset in an implantable medical device analog-to-digital converter

Abstract

In general, this disclosure describes techniques for capacitive digit-to-analog converter (CAPDAC) resetting in an implantable medical device (IMD) analog-to-digital converter (ADC). The CAPDAC of an IMD ADC may occasionally be reset to increase the accuracy of its output. The output of the CAPDAC may be disconnected from a negative feedback input of an integrator and connected to a pseudo load during the reset. Disconnecting the CAPDAC from the negative feedback input of the integrator reduces the affect of the reset on the integrator. During the reset of the CAPDAC, the negative feedback input of integrator is coupled to a sample and hold capacitor, which temporarily provides an input approximately equal to a previous, e.g., immediate, value of the output of CAPDAC prior to the reset. Thus, the resetting of the CAPDAC is done in such a manner that the affect of the reset on integrator is substantially reduced or eliminated.

Claims25

Dependent claims

An implantable medical device comprising:

at least one sensor that generates an analog input signal;
at least one analog-to-digital converter (ADC) that converts the analog input signal to a digital signal, the ADC comprising:
a continuous time (CT) integrator that integrates a difference between the analog input signal and a reconstruction of the analog input signal;
a capacitive digital-to-analog converter (CAPDAC) that includes a plurality of capacitors that are used to generate the reconstruction of the analog input signal based on the digital signal, wherein an output of the CAPDAC provides the reconstruction of the analog input signal to a negative feedback input of the CT integrator;
and
a switch that disconnects the output of the CAPDAC from the negative feedback input of the CT integrator and connects the output of the CAPDAC to a capacitive load in response to a reset signal;
and
a processor that receives the digital signal from the ADC.

5 more elements

Dependencies are inferred from the claim text.

Capacitive digital-to-analog converter reset in an implantable medical device analog-to-digital converter

Life of this patent

Capacitive digital-to-analog converter reset in an implantable medical device analog-to-digital converter

Life of this patent

Abstract

Claims25