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Activefeedback frequencycompensation technique for lowpower multistage amplifiers
 IEEE J. SolidState Circuits
, 2003
"... technique for lowpower operational amplifiers is presented in this paper. With an activefeedback mechanism, a highspeed block separates the lowfrequency highgain path and highfrequency signal path such that high gain and wide bandwidth can be achieved simultaneously in the AFFC amplifier. The ..."
Abstract

Cited by 7 (3 self)
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technique for lowpower operational amplifiers is presented in this paper. With an activefeedback mechanism, a highspeed block separates the lowfrequency highgain path and highfrequency signal path such that high gain and wide bandwidth can be achieved simultaneously in the AFFC amplifier. The gain stage in the activefeedback network also reduces the size of the compensation capacitors such that the overall chip area of the amplifier becomes smaller and the slew rate is improved. Furthermore, the presence of a lefthalfplane zero in the proposed AFFC topology improves the stability and settling behavior of the amplifier. Threestage amplifiers based on AFFC and nestedMiller compensation (NMC) techniques have been implemented by a commercial 0.8 m CMOS process. When driving a 120pF capacitive load, the AFFC amplifier achieves over 100dB dc gain, 4.5MHz gainbandwidth product (GBW) , 65 phase margin, and 1.5V / s average slew rate, while only dissipating 400 W power at a 2V supply. Compared to a threestage NMC amplifier, the proposed AFFC amplifier provides improvement in both the GBW and slew rate by 11 times and reduces the chip area by 2.3 times without significant increase in the power consumption. Index Termsâ€”Active feedback, activecapacitivefeedback network, amplifiers, frequency compensation, multistage amplifiers.
An improved bandgap reference with high power supply rejection," presented at 2002
 IEEE International Symposium on Circuits and Systems, May 2629 2002
, 2002
"... An improved bandgap reference with high power supply rejection (PSR) is presented. The proposed circuit consists of a simple voltage subtractor circuit incorporated into the conventional Brokaw bandgap reference. Essentially, the subtractor feeds the supply noise directly into the feedback loop of t ..."
Abstract

Cited by 2 (0 self)
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An improved bandgap reference with high power supply rejection (PSR) is presented. The proposed circuit consists of a simple voltage subtractor circuit incorporated into the conventional Brokaw bandgap reference. Essentially, the subtractor feeds the supply noise directly into the feedback loop of the bandgap circuit which could help to suppress supply noise. The simulation results have been shown to conform well with the theoretical evaluation. The proposed circuit has also shown robust performance across temperature and process variations. 1.
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"... In this problem, the differential gain is obtained by analyzing the circuit showed in fig 1 as a single inverter with an active load. For the PSRR expressions the circuit is divided by two cuts showed in fig 1 as C1 for Vdd and C2 for Vss and analyzed as explained in [1]. For the AVdiff, the analysi ..."
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In this problem, the differential gain is obtained by analyzing the circuit showed in fig 1 as a single inverter with an active load. For the PSRR expressions the circuit is divided by two cuts showed in fig 1 as C1 for Vdd and C2 for Vss and analyzed as explained in [1]. For the AVdiff, the analysis is the following: Figure 1 Simple OTA schematic For the PSRR, the C2 cut is used and the current passing through the points a and b is used for analysis as follows: Where sCp is the total parasitic capacitances in node a and parasitic capacitances in node b. The current flowing from Vss to Vout goes directly through go4 and other path is through M3 as a current buffer and M1 then goes through the source of M2 and finally reach Vout. For the PSRR+, the C1 cut is used and the point c is used for the analysis as follows: Where the current flowing from Vdd gets divided by the current divider seen at the sources of M1 and M2. Then one half of the current goes directly to Vout and the other half goes through the current buffer of M1, then by the current mirror this currents gets reflected and added to Vout. Problem 2: Derive differential gain and PSRR expressions for the current feedback and voltage feedback Amplifiers