An Ultra-Low Noise and Wide Output Range LDO With BJT Input Stage and Base Current Cancellation Technique

An LDO that utilizes Bipolar-Junction-Transistor (BJT) as input differential pair with base current compensation structure is proposed. The NPNs and PNPs complementary input structure is designed to suppress both the flicker and thermal noise of the LDO and ensure the rail-to-rail common mode input range. The base current compensation structure is designed to ensure the output accuracy of the LDO. Moreover, by designing the current-mode reference, the proposed LDO eliminates the thermal noise from the feedback resistor network and the amplification of the noise due to the feedback coefficient. The proposed LDO was fabricated with 180nm BCD double well process with a die area of about 2.884mm $^{\mathbf {2}}$ . The measured output noise of the LDO is only $\mathbf {248nV/}\sqrt {\mathbf {Hz}} $ at 10Hz, and the integrated RMS noise is $1.44\mu $ V from 10Hz to 100kHz. The LDO supports a wide supply rail range from 2.3V to 20V and a wide output range from 0.1V to 19.7V. The measured Line and Load regulations are 0.035mV/V and 0.0008mV/mA, respectively.