Capacitance multiplier and method

Abstract

Capacitance multiplier circuitry provides an increased equivalent capacitance, and may be implemented using a desirably small footprint. As may be implemented in accordance with one or more embodiments, a capacitor provides a first capacitance across first and second plates, and capacitance multiplier circuitry operates with the capacitor to provide a second equivalent capacitance that is a multiple of the first capacitance. The capacitance multiplier circuitry includes a first circuit path having a first resistor between the first plate and a common terminal, and a second circuit path having a switch and a second resistor between the second plate and the common terminal. An amplifier has differential inputs respectively corresponding to the first and second circuit paths and provides the second equivalent capacitance by controlling operation of the switch based upon the differential inputs and the respective resistances provided by the resistors in the first and second circuit paths.

Description

technical field [0001] Various aspects of the embodiments relate to providing capacitance multiplication. Background technique [0002] Many circuit applications benefit from or require the use of capacitors in order to ensure proper operation. For example, narrowband loop compensation circuits, boost regulators, integrated pulse-width modulator (PWM) step-up transformers, LED drivers, and low-frequency phase-locked loops (PLLs) can benefit from the use of capacitors and associated circuitry. [0003] In circuit applications, such as those involving closed-loop control of integrated circuit systems, dominant poles are often created for stabilization purposes. Such a scheme can be implemented according to control theory in the frequency domain. This dominant pole can be created by on-chip capacitors and amplifiers such as transconductance amplifiers. A left hand plane (LHP) zero is also typically created to compensate for phase shift due to existing poles in the loop. How...

AI Technical Summary

Problems solved by technology

However, for circuits such as PWM boost regulators (or transformers), the control loop bandwidth is desirably limited due to the presence of right-hand plane (RHP) zeros

[0004] Although many solutions involve providing large value compensation capacitors (for example, 300pF), such capacitors may occupy a large die area

In many implementations, this larger area is impractical or intolerable

These and other issues present challenges to the implementation of capacitors for a variety of applications

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