A 92.7%-Efficiency 6.78-MHz Dual-Output Energy-Resuscitating Resonant Regulating Rectifier for Wirelessly Powered Systems

Wirelessly powered systems, such as implantable medical devices (IMD), widely rely on a two-stage regulating structure comprising an ac-dc rectifier and a dc-dc regulator to convert the wireless power. Recently, there have been advancements aimed at enhancing power efficiency and reducing the number of output capacitors, leading to the introduction of a one-stage resonant regulating rectifier
$(\mathrm{R}^{3})$
that efficiently converts ac input into stable dc output. Fig. 1 (top) depicts this
$\mathrm{R}^{3}$
configuration, while four types of conventional
$\mathrm{R}^{3}$
structures are also illustrated in Fig. 1 (middle). The topology reconfiguration modulation (TRM)
$\mathrm{R}^{3}$
enables the receiver to switch between two modes, resulting in output options of x1 or xN [1]. Also, the pulse density modulation (PDM)
$\mathrm{R}^{3}$
allows for up to five tuning modes by determining the number of pulses required for power transfer from the
$\mathrm{L}_{2}\mathrm{C}_{2}$
tank to the load [2]. However, these discrete tuning methods deteriorate the output ripple, and the unselected pulses circulates in the
$\mathrm{L}_{2}\mathrm{C}_{2}$
tank dissipating power through the effective series resistor (ESR) of the
$\mathrm{L}_{2}\mathrm{C}_{2}$
tank. To mitigate this issue, alternative methods such as pulse width modulation (PWM) [3] and pulse width/density modulation (PWDM) [4] were investigated to control the pulse width continuously until the output voltage reaches the target voltage. However, these methods still suffer from the limitations related to the energy wastage, leading to heat generation and low power transfer to the load, which restrict their usage in IMD applications. To get the utmost out of this wasted period, the proposed energy-resuscitating resonant regulating rectifier
$(\text{ER}^{4})$
invigorates this discarded period to provide additional regulated energy, resulting in increased power delivered to the load (PDL) and continuously regulated dual output as shown in Fig. 1 (bottom).