Zhou Qianneng

A LDO regulator with slew-rate enhancement circuit for low-power SoC

A low dropout (LDO) regulator is designed in this paper. By adopting a slew rate enhancement circuit, the slew rate of the LDO output is obviously improved when the load current is suddenly switched from low to high. Moreover, employing a simple bias circuit, the architecture of the LDO regulator is simple, and can be fabricated by conventional CMOS technology. The LDO regulator is designed and simulated in CSMC 0.5µm CMOS process. Simulation results show that the PSRR of the LDO regulator at 100Hz, 1kHz and 10kHz achieves, respectively, −76dB, −70dB and −52dB at room temperature and Vdd=2V. The circuit can provide an output voltage of 1.2V with a variation of 8mV in a load current range from 0 to 50mA. The deviation of the output voltage is within 11mV when power supply voltage Vdd changes from 1.4V to 6V.

Novel high PSRR high-order temperature-compensated subthreshold MOS bandgap reference

Abstract Novel high power supply rejection ratio (PSRR) high-order temperature-compensated subthreshold metal-oxide-semiconductor (MOS) bandgap reference (BGR) is proposed in Semiconductor Manufacturing International Corporation (SMIC) 0.13 μm complementary MOS (CMOS) process. By adopting subthreshold MOS field-effect transistors (MOSFETs) and the piecewise-curvature temperature-compensated technique, the output reference voltages temperature performance of the subthreshold MOS BGR is effectively improved. The subthreshold MOS BGR achieves high PSRR performance by adopting the technique of pre-regulator. Simulation results show that the temperature coefficient (TC) of the subthreshold MOS BGR is 1.38×10−6/°C when temperature is changed from −40 °C to 125 °C with a power supply voltage of 1.2 V. The subthreshold MOS BGR achieves the PSRR of −104.54 dB, −104.54 dB, −104.5 dB, −101.82 dB and −79.92 dB at 10 Hz, 100 Hz, 1 kHz, 10 kHz and 100 kHz respectively.

Performance analysis for two-user Alamouti coded MIMO system with the PIC group decoding

Currently the research of multi-user MIMO system mainly focuses on the analysis of channel capacity. Low complexity is also attractive to the implementation of a receiver, and thus interference cancellation decoding is often adopted in practice. Partial Interference Cancellation (PIC) group decoding is one effective decoding algorithm for point-to-point MIMO systems which addressing the complexity and rate tradeoff very well. Since the decoding complexity of multi-user MIMO systems with the Maximum Likelihood (ML) decoding is very hign, PIC group decoding is a good choice for it. To clarify the performance of PIC group decoding when used in multi-user cases, this paper first derives the diversity order of two-user Alamouti coded MIMO systems with this decoding. For a two-user Alamouti coded MIMO system with N antennas at the receiver, the diversity order is 2 (N − 1) with the PIC group decoding. The conclusion can be easily extended to K-user cases, and achieve the diversity order of 2 (N − K + 1). Simulation results confirms the analytical derivation.

Novel high-PSRR high-order curvature-compensated bandgap voltage reference

Abstract This paper proposes a novel high-power supply rejection ratio (high-PSRR) high-order curvature-compensated CMOS bandgap voltage reference (BGR) in SMIC 0.18 μm CMOS process. Three kinds of current are added to a conventional BGR in order to improve the temperature drift within wider temperature range, which include a piecewise-curvature- corrected current in high temperature range, a piecewise-curvature-corrected current in low temperature range and a proportional-to-absolute-temperature T1.5 current. The high-PSRR characteristic of the proposed BGR is achieved by adopting the technique of pre-regulator. Simulation results shows that the temperature coefficient of the proposed BGR with pre-regulator is 8.42×10−6/°C from −55 °C to 125 °C with a 1.8 V power supply voltage. The proposed BGR with pre-regulator achieves PSRR of −123.51 dB, −123.52 dB, −88.5 dB and −50.23 dB at 1 Hz, 100 Hz, 100 kHz and 1 MHz respectively.