120 µH ferrite-core inductor for automotive signal filtering
The Murata LQH32NZ121J23L is a drum core wirewound inductor in the LQH32 series, rated 120 µH ±5% at 1 MHz test frequency. The 8 Ohm max DCR and 75 mA current rating define the DC bias ceiling — above 75 mA the inductance rolls off as the ferrite core saturates, so the part is sized for low-current signal conditioning, not power rail filtering. The 1210 (3225 Metric) footprint is a standard size for automotive ECU and sensor module layouts, with the unshielded construction meaning the stray field couples into adjacent traces — keep a keep-out zone under the part on the inner layers.
Q factor and self-resonant frequency
Q is 40 at 796 kHz, which sets the AC loss floor in the AM-band and low-frequency filter passband. The self-resonant frequency is 7.5 MHz — above this the inductor behaves capacitively, so the useful filter range stops well below 7.5 MHz. For a 120 µH part, the SRF is typical of a ferrite drum-core construction; the winding capacitance limits the upper frequency more than the core material.