Resonant charge pump circuit
A resonant charge pump circuit includes a resonant circuit having a bucket capacitor and a bucket inductor connected in series, and a switching circuit connected to the resonant circuit. The switching circuit switches to a first state that enables current to flow from an input terminal into the resonant circuit to charge the bucket capacitor and the bucket inductor, and switches to a second state that enables current to flow from the resonant circuit to discharge the bucket capacitor and the bucket inductor to an output terminal. The resonant circuit controls current flow into and out from the resonant circuit when the switching circuit switches between the states. The resonant charge pump circuit also includes a timing circuit that controls when the switching circuit switches between the states.
1. A resonant charge pump circuit, comprising:
a first switching element operably connected to a second switching element at a first node, the first switching element and the second switching element operably connected in series between an input terminal and an output terminal;
a resonant circuit operably connected between the first node and a second node, the resonant circuit having a bucket capacitor and a bucket inductor connected in series;
a synchronization circuit operably connected to the second node and operable to output a first control signal and a second control signal when a predetermined current level through the resonant circuit is not detected, wherein the first control signal is operable to control a state of the first switching element and the second control signal is operable to control a state of the second switching element; and
wherein the synchronization circuit comprises:
a detector circuit operably connected to the second node, the detector circuit operable to detect a current level through the resonant circuit; and
an alternate clock generator operable to output an alternate clock signal that is operable to cause the first control signal and the second control signal to be output when the predetermined current level is not detected.
2. The resonant charge pump circuit of claim 1 , wherein:
the first control signal and the second control signal are synchronized and complementary;
the first control signal is operable to control the state of the first switching element to connect the input terminal to the resonant circuit and to disconnect the input terminal from the resonant circuit; and
the second control signal is operable to control the state of the second switching element to connect the resonant circuit to the output terminal and to disconnect the resonant circuit from the output terminal.
3. The resonant charge pump circuit of claim 1 , wherein the synchronization circuit comprises:
a toggle circuit operably connected to the detector circuit and to the alternate clock generator, the toggle circuit operable to output the second control signal; and
an inverter circuit operably connected to the toggle circuit, the inverter circuit operable to output the first control signal.
4. The resonant charge pump circuit of claim 1 , wherein the predetermined current level is zero.
5. The resonant charge pump circuit of claim 1 , further comprising:
a third switching element operably connected to the input terminal; and
a fourth switching element operably connected in series with the third switching element at a third node, wherein the second control signal is operable to control a state of the third switching element and the first control signal is operable to control a state of the fourth switching element.
6. A resonant charge pump circuit, comprising:
a first switching element operably connected to a second switching element at a first node, the first switching element and the second switching element operably connected in series between an input terminal and an output terminal;
a third switching element operably connected to the input terminal;
a fourth switching element operably connected to the third switching element at a second node, the third switching element and the fourth switching element operably connected in series;
a resonant circuit operably connected between the first node and a third node, the resonant circuit having a bucket capacitor and a bucket inductor connected in series; and
a synchronization circuit operably connected to the second node and to the third node and operable to output a first control signal and a second control signal when a predetermined current level through the resonant circuit is not detected, wherein:
the first control signal is operable to control a state of the first switching element and a state of the fourth switching element;
the second control signal is operable to control a state of the second switching element and a state of the third switching element; and
wherein the synchronization circuit comprises:
a detector circuit operably connected to the second node, the detector circuit operable to detect a current level through the resonant circuit; and
an alternate clock generator operable to output an alternate clock signal that is operable to cause the first control signal and the second control signal to be output when the predetermined current level is not detected.
7. The resonant charge pump circuit of claim 6 , further comprising:
a first diode operably connected across the first switching element; and
a second diode operably connected across the second switching element.
8. The resonant charge pump circuit of claim 6 , wherein the predetermined current level is zero.
9. The resonant charge pump circuit of claim 6 , wherein the first control signal and the second control signal are synchronized and complementary.
10. The resonant charge pump circuit of claim 6 , wherein:
the first control signal is operable to cause the first switching element to connect the input terminal to the resonant circuit when the first switching element is in a first state and cause the first switching element to disconnect the input terminal from the resonant circuit when the first switching element is in a second state;
the second control signal is operable to cause the second switching element to connect the resonant circuit to the output terminal when the second switching element is in the first state and to cause the second switching element to disconnect the output terminal from the resonant circuit when the second switching element is in the second state;
the first control signal is operable to cause the fourth switching element to connect the second node to ground when the fourth switching element is in the first state and cause the fourth switching element to disconnect the second node from the ground when the fourth switching element is in the second state; and
the second control signal is operable to cause the third switching element to connect the second node to the input terminal when the third switching element is in the first state and to cause the third switching element to disconnect the second node from the input terminal when the third switching element is in the second state.
11. The resonant charge pump circuit of claim 6 , wherein the first switching element, the second switching element, the third switching element, and the fourth switching element each comprise transistors.
12. The resonant charge pump circuit of claim 6 , wherein the synchronization circuit synchronizes the switching of the first switching element, the second switching element, the third switching element, and the fourth switching element to a resonant frequency of the resonant circuit.
13. A method for operating a resonant charge pump circuit having a resonant circuit that includes a bucket capacitor and a bucket inductor, the method comprising:
switching to a first state that enables current to flow from an input terminal into the resonant circuit to charge the bucket capacitor and the bucket inductor;
switching to a second state that enables the current to flow from the resonant circuit to an output terminal to discharge the bucket capacitor and the bucket inductor;
determining a current level through the resonant circuit;
based on a determination that the current level through the resonant circuit is greater than a predetermined current level, synchronizing the switching between the first state and the second state by using an alternate clock signal generated in a synchronization circuit to control the current flows from the input terminal to the output terminal; and
based on a determination that the current level through the resonant circuit is at the predetermined current level, synchronizing the switching between the first state and the second state by using a pulse signal generated in the synchronization circuit to control the current flows from the input terminal to the output terminal, wherein:
the alternate clock signal and the pulse signal are operable to cause a first control signal and a second control signal to be used to control the switching between the first state and the second state;
the first control signal controls the switching to the first state; and
the second control signal controls the switching to the second state.
14. The method of claim 13 , wherein the first control signal and the second control signal are complementary and synchronized to a resonant frequency of the resonant circuit.
15. The method of claim 13 , wherein the predetermined current level is zero current.