DIGITAL CHARGE AMPLIFIER AND METHOD FOR CONVERTING CHARGE SIGNALS INTO DIGITAL SIGNALS
First Claim
1. Charge amplifier circuit for converting positive and negative charge signals Q that are output by a piezoelectric measuring element into a digital signal D that is proportional to the present measured value at the measuring element, comprising a charge amplifier V1 having a charge input and a voltage output for converting the detected charge Q into a voltage U2, wherein a compensation circuit K comprising two outputs is connected downstream of the voltage output of the charge amplifier V1, wherein the first output is connected to the charge input of the charge amplifier V1 and the second output to a counter Z having two inputs Z+, Z−
- , and wherein on the one hand, the compensation circuit K can produce a compensation charge Qk+ or Qk−
respectively, that is proportional to the voltage U2 and that can be sent to the charge input of the charge amplifier V1 by means of the first output in order to compensate the input signal 0, and wherein on the other hand the compensation circuit can produce a number of pulses P+, P−
that is proportional to the magnitude of each compensation charge Qk+ or Qk−
produced, and said pulses can be sent to an input Z−
, Z+ of the counter Z opposite the sign of the particular compensation charge Qk+ or Qk−
by means of the second output, wherein the desired digital signal D, which is proportional to the sum of the charge quanta input beforehand, is available at the output of the counter Z.
1 Assignment
0 Petitions
Accused Products
Abstract
A circuit for a charge amplifier for converting piezoelectric measurement signals continuously sets the output signal of the amplifier to a value close to zero, such that a reset switch becomes unnecessary. The amplifier includes a pulse generator that provides the output signal of the amplifier in the form of pulses, which are easy to transmit with low interference. The pulse frequency is proportional to the rate of change of charge. The pulses, which are added in a counter, represent a value proportional to the change in the charge since the last counter reset, which is proportional to the present measured value at the measurement element.
-
Citations
13 Claims
-
1. Charge amplifier circuit for converting positive and negative charge signals Q that are output by a piezoelectric measuring element into a digital signal D that is proportional to the present measured value at the measuring element, comprising a charge amplifier V1 having a charge input and a voltage output for converting the detected charge Q into a voltage U2, wherein a compensation circuit K comprising two outputs is connected downstream of the voltage output of the charge amplifier V1, wherein the first output is connected to the charge input of the charge amplifier V1 and the second output to a counter Z having two inputs Z+, Z−
- , and wherein on the one hand, the compensation circuit K can produce a compensation charge Qk+ or Qk−
respectively, that is proportional to the voltage U2 and that can be sent to the charge input of the charge amplifier V1 by means of the first output in order to compensate the input signal 0, and wherein on the other hand the compensation circuit can produce a number of pulses P+, P−
that is proportional to the magnitude of each compensation charge Qk+ or Qk−
produced, and said pulses can be sent to an input Z−
, Z+ of the counter Z opposite the sign of the particular compensation charge Qk+ or Qk−
by means of the second output, wherein the desired digital signal D, which is proportional to the sum of the charge quanta input beforehand, is available at the output of the counter Z. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
- , and wherein on the one hand, the compensation circuit K can produce a compensation charge Qk+ or Qk−
-
13. Method for converting positive and negative charge signals Q that are output by a piezoelectric measuring element into a digital signal D that is proportional to the present measured value at the measuring element, comprising the steps that:
- a charge amplifier V1 converts the input charge signal Q into an analogue voltage signal U2, the voltage signal U2 is passed into a compensation circuit K downstream of the charge amplifier V1, on the one hand the compensation circuit K produces a compensation charge Qk+ or Qk−
respectively that is proportional to the voltage U2 and, to compensate the input signal Q, sends it to the charge input of the charge amplifier V1 by means of a first output, and that on the other hand the compensation circuit K produces a number of pulses P+, P−
that is proportional to the magnitude of each compensation charge Qk+ or Qk−
produced and sends them to an input Z−
, Z+ of the counter Z opposite the sign of the particular compensation charge Qk+ or Qk−
by means of the second output, and said counter sums the pulses and delivers the respective sum as the desired digital signal D.
- a charge amplifier V1 converts the input charge signal Q into an analogue voltage signal U2, the voltage signal U2 is passed into a compensation circuit K downstream of the charge amplifier V1, on the one hand the compensation circuit K produces a compensation charge Qk+ or Qk−
Specification