Bridges Supplied by Two Current Sources - New Tool for Impedance Measurements and Signal Conditioning
Zygmunt L. Warsza
Abstract:
A new type of measuring circuitry is presented. It is an impedance bridge unconventionally supplied by two current sources connected in parallel to opposite arms of the bridge. This circuit has two independent balance states, when voltage on each output -? bridge diagonals ?- equals zero. If two current sources are ideal and identical, the equality of impedance products of neighboring arms of the output diagonal are the balance conditions. These two relations are different from the one of the classic Wheastone bridge. The author proposes to call this new type of circuits as: double current bridge . Formulas for currents, voltages and powers of the bridge arms in balance conditions are given. Sensitivities of such circuits and their optimization have been discussed. The method of measurements when current sources are not identical is also proposed. Expressions for output voltages of unbalanced circuit are given. The possibility of simultaneous measurement of two variables by a pair of sensors and measurements of increments of every sensor without disconnecting the bridge are also presented. Some conclusions and directions of future developments in this area are also included.
