Miller theorem

Abstract: A DC-DC converter includes an error amplifier that includes an operational transconductance amplifier (OTA), a compensation circuit, and a fast transient controller. The OTA includes a compensation resistor, a compensation capacitor of C z , and a Miller circuit. The equalization capacitance generated by the compensation capacitor and the Miller circuit is (1+k) C z . The Miller circuit includes three transistors operated in the triode region. The ratio of the current through the transistors is 1:mk:(1−m)k. The current through the compensation capacitor in a second mode is (1+mk) times that in a first mode. The fast transient controller switches the Miller circuit between the first and second modes according to a feedback voltage dependent on the output voltage of the DC-DC converter.

Abstract: Four general Miller equivalent circuits, one for each of the four possible connections of two two-port networks, are derived. Based on these, a generalized Miller theorem is stated. A number of illustrative examples are included to demonstrate the power of the Miller theorem as an analytical tool in the analysis and synthesis of networks. It is pointed out that many known results such as capacitance multiplication, high input impedance of the emitter follower and the Darlington pair, and synthesis of driving point and transfer functions by some network configurations can be understood through the Miller theorem. >

Abstract: A two-stage amplifier with active miller compensation is presented in this paper. Unlike the two-stage amplifier with conventional miller compensation, the proposed structure doesn't contain right half plane zero. What is more, a left half plane zero is created to cancel the first non-dominant pole. The proposed structure improves the bandwidth significantly and reduces the dimension of the compensation capacitor. The proposed two-stage amplifier is designed and simulated in standard 0.6µm CMOS process. Simulation results show that the unit-gain frequency is increased by 9.4 times with only 38% increase in power consumption. The overall FoM is improved by 31.5 times.

Abstract: This paper presents two novel active-feedback single Miller capacitor frequency compensation techniques for low-power three-stage amplifiers. These techniques include the active-feedback single Miller capacitor frequency compensation (AFSMC) and the dual active-feedback single Miller capacitor frequency compensation (DAFSMC). In the proposed techniques, only one Miller capacitor in series with a current buffer is utilized. The main advantages of the proposed three-stage amplifiers are the enhanced unity-gain bandwidth and the reduced silicon area. Small-signal analyses are performed and the design equations are obtained. Extensive HSPICE simulation results are provided to show the usefulness of the proposed AFSMC and DAFSMC amplifiers in both large and small capacitive loads.