US 5,206,648 A · Oversampling DA converter with operational amplifier driven by a single reference voltage

Abstract

In an oversampling digital-to-analog converter, an input 16-bit word digital signal is oversampled and quantized by a delta-sigma modulator into one of discrete values of +1, 0 and -1. A leaky integrator is coupled between the input and output terminals of an operational amplifier. A capacitor is charged by drawing a unit charge from a reference voltage source during a first half of the sample period of the +1 discrete value and discharged by injecting a unit charge to the input terminal of the operational amplifier during a second half of the sample period of the +1 discrete value. The capacitor is discharged during a first half of the sample period of the -1 discrete value and charged by drawing a unit charge from the input terminal of the operational amplifier during a second half of the sample period of the -1 discrete value. During the sample period of the 0 discrete value, the capacitor maintains a condition that occurs therein during the second half of the sample period of either of the +1 or -1 discrete value.

Claims8

Dependent claims

An oversampling digital-to-analog converter comprising:

oversampling means for oversampling a digital signal to produce an oversampled digital signal;
delta-sigma modulator means for quantizing said oversampled digital signal into one of discrete values of +1, 0 and -1;
an operational amplifier and a leaky integrator coupled between input and output terminals of the operational amplifier;
a capacitor;
a reference voltage source;
and
logic switching means coupled to said delta-sigma modulator means and said capacitor for charging the capacitor by drawing a unit charge from said reference voltage source during a first half of the sample period of said +1 discrete value and discharging the capacitor by injecting a unit charge to the input terminal of said operational amplifier during a second half of the sample period of said +1 discrete value, for discharging the capacitor during a first half of the sample period of said -1 discrete value and charging the capacitor by drawing a unit charge from the input terminal of said operational amplifier during a second half of the sample period of said -1 discrete value, and causing said capacitor to maintain a most recent condition thereof during the sample period of said 0 discrete value.

4 more elements

An oversampling digital-to-analog converter comprising:

oversampling means for oversampling a digital signal to produce an oversampled digital signal;
delta-sigma modulator means for quantizing said oversampled digital signal into one of discrete values of +1, 0 and -1;
a balanced operational amplifier having first and second input terminals and first and second output terminals;
a first leaky integrator coupled between the first input terminal and first output terminal of the balanced operational amplifier and a second leaky integrator coupled between the second input terminal and second output terminal of the balanced operational amplifier;
first and second capacitors;
a reference voltage source;
and
logic switching means coupled to said delta-sigma modulator means and said first and second capacitors for:
(a) charging said first capacitor by drawing a unit charge from said reference voltage source during a first half of the sample period of said +1 discrete value and discharging said first capacitor by drawing a unit charge from the first input terminal of said operational amplifier during a second half of the sample period of said +1 discrete value;
(b) discharging said first capacitor during a first half of the sample period of said -1 discrete value and charging the first capacitor by drawing a unit charge from the reference voltage source and injecting the charge to the first input terminal of said operational amplifier during a second half of the sample period of said -1 discrete value;
(c) discharging said second capacitor during the first half of the sample period of said +1 discrete value and charging said second capacitor by drawing a unit charge from the reference voltage source and injecting the charge to the second input terminal of said operational amplifier during the second half of the sample period of said +1 discrete value;
(d) charging said second capacitor by drawing a unit charge from the reference voltage source during the first half of the sample period of said -1 discrete value and discharging the second capacitor by drawing a unit charge from the second input terminal of said operational amplifier during the second half of the sample period of said -1 discrete value;
and (e) causing each of said first and second capacitors to maintain a most recent condition thereof during the sample period of said 0 discrete value.

10 more elements

An oversampling digital-to-analog converter comprising:

oversampling means for oversampling a digital signal to produce an oversampled digital signal;
delta-sigma modulator means for quantizing said oversampled digital signal into one of discrete values of +1, 0 and -1;
a balanced operational amplifier having first and second input terminals and first and second output terminals;
a first leaky integrator coupled between the first input terminal and first output terminal of the balanced operational amplifier and a second leaky integrator coupled between the second input terminal and second output terminal of the balanced operational amplifier;
first and second capacitors;
a reference voltage source;
and
logic switching means coupled to said delta-sigma modulator means and said first and second capacitors for:
(a) charging said first capacitor by drawing a unit charge from said reference voltage source during a first half of the sample period of said +1 discrete value and discharging said first capacitor by injecting a unit charge to the first input terminal of said operational amplifier during a second half of the sample period of said +1 discrete value;
(b) discharging said first capacitor during a first half of the sample period of said -1 discrete value and charging the first capacitor by drawing a unit charge from the reference voltage source and injecting the charge to the second input terminal of said operational amplifier during a second half of the sample period of said -1 discrete value;
(c) discharging said second capacitor during the first half of the sample period of said +1 discrete value and charging said second capacitor by drawing a unit charge from the reference voltage source and injecting the charge to the second input terminal of said operational amplifier during the second half of the sample period of said +1 discrete value;
(d) charging said second capacitor by drawing a unit charge from the reference voltage source during the first half of the sample period of said -1 discrete value and discharging the second capacitor by drawing a unit charge from the first input terminal of said operational amplifier during the second half of the sample period of said -1 discrete value;
and (e) causing each of said first and second capacitors to maintain a most recent condition thereof during the sample period of said 0 discrete value.

10 more elements

Dependencies are inferred from the claim text.

Oversampling DA converter with operational amplifier driven by a single reference voltage

Life of this patent

Oversampling DA converter with operational amplifier driven by a single reference voltage

Life of this patent

Abstract

Claims8