Hybrid cascode compensation with current amplifiers for nano-scale three-stage amplifiers driving heavy capacitive loads

Dual loop cascode‐Miller compensation with damping factor control unit for three‐stage amplifiers driving ultralarge load capacitors

“…[1][2][3][4][5][6][7][8][9] To maintain the high accuracy required for these applications, the amplifier should be designed such that, under different conditions, it exhibits a high open-loop DC gain. [1][2][3][4][5][6][7][8][9] To maintain the high accuracy required for these applications, the amplifier should be designed such that, under different conditions, it exhibits a high open-loop DC gain.…”

“…[1][2][3][4][5][6][7][8][9] To maintain the high accuracy required for these applications, the amplifier should be designed such that, under different conditions, it exhibits a high open-loop DC gain. Figure 1 illustrates a number of possible solutions found in the literature, 1,2,7, where capacitors and transconductors are represented using familiar notations. Less voltage headroom is also available in nanoscale technologies, making it difficult to cascode multiple MOS devices in such low-voltage environment.…”

“…Simulation results of a DLCDFC prototype incorporating the new compensation strategy are addressed in section 3, to verify its advantages in terms of area and consuming power. 7,11,15,16,18,20 Furthermore, the compensation capacitors are now connected to the input of two current buffers with reduced input resistors of 1/g mC1 and 1/g mC2 , rather than the high-impedance v O1 node of the first stage output. The ac feedback loops along with the local damping factor control block all contribute to the proposed DLCDFC frequency compensation scheme, which differs in many ways from the previous frequency compensation schemes depicted in Figure 1.…”

“…Multistage amplifiers capable of driving ultralarge load capacitors are among the basic block diagrams used in many types of data converters, analog filters, low-dropout regulators, headphones, audio amplifiers, and active-matrix liquid crystal display (LCD) column drivers. [1][2][3][4][5][6][7][8][9] To maintain the high accuracy required for these applications, the amplifier should be designed such that, under different conditions, it exhibits a high open-loop DC gain. Achieving a high DC gain is not, however, straightforward in nanoscale complementary metal-oxide-semiconductor (CMOS) technologies, as intrinsic gain of CMOS devices is degrading continuously with the advancement of technology.…”

“…2,10 Due to several poles appearing in their voltage-gain transfer function, multistage amplifiers are potentially unstable in feedback configuration, and a robust frequency compensation strategy is required. Figure 1 illustrates a number of possible solutions found in the literature, 1,2,7, where capacitors and transconductors are represented using familiar notations. The approximated voltage-gain transfer function and the magnitude and the quality factor of the nondominant pole(s) are also presented beside each amplifier topology, enabling a quick visual comparison among different solutions.…”