A new frequency compensation method based on differential current conveyor

Abstract

A new frequency compensation scheme using a second generation differential current conveyor (DCCII) for three-stage amplifiers is proposed. By adding a DCCII as a feedback path from output of the second and the third stage to the output of the first stage, feed-forward path and the right-half plane zero will be removed subsequently which improves phase margin and the gain-bandwidth product. Calculations are derived for two states. First state, a DCCII and two miller capacitors form the feedback paths and in the second state, two nulling resistors are series with miller capacitors. Analyses show that in both states, stability can be perfectly ensured.To demonstrate advantages of this technique over the traditional RNMC architecture, a three-stage amplifier is designed and simulated employing the proposed technique in a standard 0.18μm CMOS process. Simulation results show that, with the same load capacitance, the new amplifier has improved stabilities over the conventional RNMC amplifiers by more than 22° and 0.23MHz in the phase margin and gain-bandwidth product, respectively. The proposed amplifier dissipates less than 0.45 mW of power with a 1.8 V supply.

An improved frequency compensation for three‐stageCMOSamplifier

“…[17][18][19][20][21][22][23][24][25] The main issue related to multi-stage amplifiers is stability problem due to existence of several nodes, wherein each node presents a pole and zero in transfer function (TF) description. 1,[26][27][28][29] So, performing frequency compensation turns to major difficulty for multi-stage amplifier design. In this regard, a compensation network can attach to the main amplifier to relocate poles or cancel them by zeros, which stabilize frequency response.…”

Nonlinear current source charge scheme for comparator based switched capacitor integrator

“…While cascode approach is not compatible with low voltage operation due to voltage swing reduction . And also more importantly multistage designs need frequency compensation to avoid instability issues …”

Differential block frequency compensation for low‐power multistage amplifiers

“…Unfortunately, the high‐frequency gain reduction is caused by the shorting effect of inner capacitor, which limits the bandwidth of three‐stage amplifiers based on the RNMC technique. Thereby, other recent compensation schemes use the external Miller capacitor of compensation network in order to improve both small and large signal performances …”