Voltage isolation circuit for a measurement channel
First Claim
1. A voltage isolation circuit for a measurement instrument, comprising:
- (a) a high frequency path having an input for receiving an input signal, said high frequency path producing an electrically isolated high frequency output signal according to a first transition frequency;
(b) a low frequency path having an input for receiving said input signal, said low frequency path producing an electrically isolated low frequency output signal and further producing a low frequency subtract signal according to a second transition frequency which is coupled to said input of said high frequency path to obtain a compensated high frequency path; and
(c) a summing node for combining said electrically isolated high frequency output signal with said electrically isolated low frequency output signal.
1 Assignment
0 Petitions
Accused Products
Abstract
A voltage isolation circuit having an improved method of combining the HF path and LF path is provided. The LF path comprises an opto-isolator to achieve voltage isolation of the input signal while passing low frequencies. The HF path comprises a transformer to achieve voltage isolation of the input signal while passing high frequencies. The HF path and LF path are combined at a summing node to obtain an isolated input signal. Obtaining a flat frequency response requires that the cross-over frequency between the LF path and HF path be closely matched. A portion of the LF path is injected into the HF path such that LF components are canceled out in the region of the transition frequency. In this way, the pole frequency of the transformer in the HF path may be compensated for to achieve a flat frequency response for the combined LF and HF paths.
21 Citations
10 Claims
-
1. A voltage isolation circuit for a measurement instrument, comprising:
-
(a) a high frequency path having an input for receiving an input signal, said high frequency path producing an electrically isolated high frequency output signal according to a first transition frequency; (b) a low frequency path having an input for receiving said input signal, said low frequency path producing an electrically isolated low frequency output signal and further producing a low frequency subtract signal according to a second transition frequency which is coupled to said input of said high frequency path to obtain a compensated high frequency path; and (c) a summing node for combining said electrically isolated high frequency output signal with said electrically isolated low frequency output signal. - View Dependent Claims (2, 3)
-
-
4. A voltage isolation circuit for a measurement instrument, comprising:
-
(a) an input terminal for receiving an input signal; (b) a high frequency path coupled to said input terminal for producing a high frequency output signal according to a first transition frequency, said high frequency path including a transformer for isolating said high frequency output signal from input terminal; (c) a low frequency path coupled to said input terminal for producing a low-frequency output signal according to a second transition frequency, said low frequency path including an opto-coupler for isolating said low frequency output signal from input terminal; (d) means for providing an interpath compensation signal from one of said high frequency path and said low frequency path to the other of said high frequency path and said low frequency path to match said first and second transition frequencies; and (e) a summing node coupled to the outputs of said high frequency path and said low frequency path to sum said high frequency output signal and said low frequency output signal. - View Dependent Claims (5, 6, 7, 8, 9, 10)
-
Specification