Reducing AC impedance measurement errors caused by the DC voltage dependence of broadband high-voltage bias-tees

During the AC impedance characterization of devices, from the kHz-range up to the GHz-range, accuracy can be lost when a DC voltage is applied. Commercial high-voltage broadband bias-tees are often voltage-dependent, which can cause inaccuracies at low frequencies. A calibration technique with applied bias significantly improves the measurement accuracy. Additionally, a bias-tee has been developed with a voltage-independent capacitor, suitable for DC voltages up to 500 V showing excellent performance up to several gigahertz. PIN diode limiters protect the measurement equipment from damage in case of a device breakdown.