US 6,611,168 B1 · Differential parametric amplifier with physically-coupled electrically-isolated micromachined structures

Abstract

A micromachined variable capacitor structure is used as a modulation mechanism for a differential parametric amplifier. The capacitance of the capacitor structure is modulated by a control signal while a differential signal is applied to the capacitor structure. Modulation of the capacitance produces a signal representative of the input differential voltage. This signal is provided to an amplifier. Once the signal is amplified, a demodulator demodulates the amplified signal to provide an amplified version of the differential signal. The variable capacitor structure also allows for internal feedback, which permits the parametric amplifier to be used as a galvanically isolated differential measurement amplifier. A number of techniques are used to remove common mode and other errors from the modulated difference signal, thereby eliminating them from the amplified output.

Claims35

Dependent claims

A parametric amplifier comprising:

at least a first variable capacitor structure, the first variable capacitor structure including one or more sections of oscillating capacitive elements comprising cooperating fixed and movable electrodes, the movable electrodes connected to a common center structure;
an ac amplifier operatively connected to the center structure,
a demodulator operatively connected to the ac amplifier;
and
wherein the first variable capacitor structure transduces a differential input signal applied with first polarity across the capacitive elements into a modulated input signal, the ac amplifier receives the modulated input signal via the center structure and outputs an amplified modulated input signal, the demodulator receives the amplified modulated input signal and demodulates the amplified modulated input signal to output an amplified input signal.

2 more elements

A microfabricated parametric amplifier for generating an output voltage by amplifying a differential input voltage, the parametric amplifier comprising:

at least a first micromachined variable capacitor structure having the differential input voltage applied across oscillating capacitive elements of the first capacitor structure to transduce the differential input voltage into a first electric current corresponding to a modulated form of the differential input voltage;
an ac amplifier receiving the first electric current and outputting an amplified electric current;
a demodulator demodulating the amplified electric current to generate a demodulated electric current corresponding to an amplified form of the differential input voltage, and
wherein the output voltage is generated from the demodulated electric current.

1 more element

Dependencies are inferred from the claim text.

Differential parametric amplifier with physically-coupled electrically-isolated micromachined structures

Life of this patent

Differential parametric amplifier with physically-coupled electrically-isolated micromachined structures

Life of this patent

Abstract

Claims35