lcr tester_lcr tester price_lcr tester principle

LCR tester can accurately and stably measure various component parameters, and is mainly used to test inductance, capacitance, and resistance. It has the characteristics of direct function and easy operation, and can meet the testing requirements of production line quality assurance, incoming inspection, and electronic maintenance industry for components with a low budget.

Vx and Vr are both vector voltmeters, and Rr is an ideal resistor. The meaning of a self-balancing bridge is that when the DUT (Device Under Test) is connected to the circuit, the negative feedback configuration of the amplifier automatically makes the OP input terminal a virtual ground. Vx accurately measures the voltage across the DUT (the Low potential of the DUT is 0), and Vr and Rr measure the DUT current Ix, from which Zx can be calculated.

The configuration of the test terminals Hp, Hc, Lp, Lc (subscript c stands for current, subscript p stands for potentail) and guard (grounding) of HP4275 may lead to differences in test errors.

The method to improve accuracy is: 1. Hp, Lp, Hc, Lc are as close to DUT as possible; 2. Reduce the loop area and magnetic flux of the test current Ix (the key is to analyze Ix, and use Guard and Cable to minimize the loop area); 3. Use Guard and Cable to build a ground plane to interrupt the electric field connection between signal lines. Although it will increase the capacitance of the signal line to ground (the capacitance to ground does not affect the test results), it will reduce the mutual capacitance of the signal line.

The parasitic impedance of Guard and Cable to ground (Zhg, Zlg) does not affect the test results. When the bridge is balanced, the voltage across Zlg is 0, and the current flowing to Rr will not be shunted by Zlg. The shunting effect of Zhg does not affect the voltage measurement of Hp.