AC-to-DC charge pump having a charge pump and complimentary charge pump
An improved AC-to-DC charge pump for use, for example, in voltage generation circuits. In one embodiment, two 2-diode charge pumps are coupled in back-to-back configuration, and adapted to develop a substantially stable voltage on a mid-level rail. In one other embodiment, two 3-diode charge pumps are coupled in back-to-back configuration, and adapted also to develop a substantially stable voltage on a mid-level rail. In one preferred embodiment, all diodes are implemented as current-source-biased MOSFETs.
1. An AC-to-DC charge pump comprising:
a charge pump operable to convert an AC (alternating current) input voltage into a DC (direct current) voltage, wherein the charge pump includes a current-source-biased N-channel MOSFET diode and a current-source-biased P-channel MOSFET diode, wherein the current-source-biased N-channel MOSFET diode includes:
a first N channel MOSFET;
a second N channel MOSFET; and
a capacitor, wherein:
gates of the first and second N channel MOSFETs are coupled together,
sources of the first and second N channel MOSFETs are coupled together to provide a cathode of the current-source-biased N-channel MOSFET diode;
a drain of the first N channel MOSFET is coupled to a common connection of the gates to receive a bias current,
a drain of the second N channel MOSFET provides an anode of the current-source-biased N-channel MOSFET diode; and
the capacitor is coupled between the drain of the second N channel MOSFET and the common connection of the gates; and
a complimentary charge pump operable to convert the AC input voltage into a complimentary DC voltage, wherein a magnitude of the DC voltage is substantially equal to a magnitude of the complimentary DC voltage, wherein the charge pump is coupled to the complimentary charge pump to add the DC voltage and the complimentary DC voltage to produce an output voltage, which has a middle rail that is coupled to a negative leg (V INN ) of the AC input voltage, wherein the middle rail has a common-mode voltage (V MID ), and wherein the common: mode voltage is shared by the negative leg and a positive leg (V INP ) of the AC input voltage.
2. The charge pump of claim 1 wherein the charge pump comprises:
an input capacitor;
a first diode circuit as the current-source-biased N-channel MOSFET diode;
a second diode circuit as the current-source-biased P-channel MOSFET diode; and
an output capacitor, wherein a first node of the input capacitor is coupled to the positive leg of the AC input voltage (V INP ), wherein a second node of the input capacitor is coupled to a flying node, wherein a cathode of the first diode circuit is coupled to the flying node and an anode of the first diode circuit is coupled to the middle rail, wherein an anode of the second diode circuit is coupled to the flying node and a cathode of the second diode circuit is coupled to an output node, and wherein a first node of the output capacitor is coupled to the output node and a second node of the output capacitor is coupled to the middle rail.
3. The charge pump of claim 2 wherein the current-source-biased P-channel MOSFET diode comprises:
a first P channel MOSFET;
a second P channel MOSFET; and
a capacitor, wherein:
gates of the first and second P channel MOSFETs are coupled together,
sources of the first and second P channel MOSFETs are coupled together to provide a cathode of the second diode circuit;
a drain of the first P channel MOSFET is coupled to a common connection of the gates of the first and second P channel MOSFETs to receive a bias current, and
a drain of the second P channel MOSFET provides an anode of the second diode circuit; and
the capacitor is coupled between the common connection of the sources and the common connection of the gates.
4. The charge pump of claim 1 wherein the complimentary charge pump comprises:
an input capacitor;
a first diode circuit;
a second diode circuit; and
an output capacitor, wherein a first node of the input capacitor is coupled to the positive leg of the AC input voltage (V INP ), wherein a second node of the input capacitor is coupled to a flying node, wherein an anode of the first diode circuit is coupled to the flying node and a cathode of the first diode circuit is coupled to the middle rail, wherein a cathode of the second diode circuit is coupled to the flying node and an anode of the second diode circuit is coupled to an output node (V SS ), and wherein a first node of the output capacitor is coupled to the output node and a second node of the output capacitor is coupled to the middle rail.
5. The charge pump of claim 4 further comprises:
the second diode circuit including a second current-source-biased N-channel MOSFET diode; and
the first diode circuit including a second current-source-biased P-channel MOSFET diode.
6. An integrated system comprising:
an antenna;
a tank circuit coupled to the antenna;
an AC-to-DC charge pump circuit coupled to the tank circuit, wherein the AC-to-DC charge pump circuit includes:
a charge pump operable to convert an AC (alternating current) input voltage received via the antenna into a DC (direct current) voltage, wherein the charge pump includes a current-source-biased N-channel MOSFET diode and a current-source-biased P-channel MOSFET diode, wherein the current-source-biased N-channel MOSFET diode includes:
a first N channel MOSFET;
a second N channel MOSFET; and
a capacitor, wherein:
gates of the first and second N channel MOSFETs are coupled together,
sources of the first and second N channel MOSFETs are coupled together to provide a cathode of the current-source-biased N-channel MOSFET diode;
a drain of the first N channel MOSFET is coupled to a common connection of the gates to receive a bias current,
a drain of the second N channel MOSFET provides an anode of the current-source-biased N-channel MOSFET diode; and
the capacitor is coupled between the drain of the second N channel MOSFET and the common connection of the gates; and
a complimentary charge pump operable to convert the AC input voltage into a complimentary DC voltage, wherein a magnitude of the DC voltage is substantially equal to a magnitude of the complimentary DC voltage and wherein the charge pump is coupled to the complimentary charge pump to add the DC voltage and the complimentary DC voltage to produce an output voltage, which has a middle rail that is coupled to a negative leg (V INN ) of the AC input voltage, wherein the middle rail has a common-mode voltage (V MID ), and wherein the common: mode voltage is shared by the negative leg and a positive leg (V INP ) of the AC input voltage.
7. The integrated system of claim 6 , wherein the charge pump circuit comprises:
an input capacitor;
a first diode circuit as the current-source-biased N-channel MOSFET diode;
a second diode circuit as the current-source-biased P-channel MOSFET diode; and
an output capacitor, wherein a first node of the input capacitor is coupled to the positive leg of the AC input voltage (V INP ), wherein a second node of the input capacitor is coupled to a flying node, wherein a cathode of the first diode circuit is coupled to the flying node and an anode of the first diode circuit is coupled to the middle rail, wherein an anode of the second diode circuit is coupled to the flying node and a cathode of the second diode circuit is coupled to an output node (V O ), and wherein a first node of the output capacitor is coupled to the output node and a second node of the output capacitor is coupled to the middle rail.
8. The integrated system of claim 7 further comprises:
the current-source-biased P-channel MOSFET diode includes:
a first P channel MOSFET;
a second P channel MOSFET; and
a second capacitor, wherein:
gates of the first and second P channel MOSFETs are coupled together,
sources of the first and second P channel MOSFETs are coupled together to provide a cathode of the second diode circuit;
a drain of the first P channel MOSFET is coupled to a common connection of the gates of the first and second P channel MOSFETs to receive a bias current, and
a drain of the second P channel MOSFET provides an anode of the second diode circuit; and
the second capacitor is coupled between the common connection of the sources of the first and second P channel MOSEFTs and the common connection of the gates of the first and second P channel MOSEFTs.
9. The integrated system of claim 7 , wherein the complimentary charge pump comprises:
an input capacitor;
a first diode circuit;
a second diode circuit; and
an output capacitor, wherein a first node of the input capacitor is coupled to the positive leg of the AC input voltage (V INP ), wherein a second node of the input capacitor is coupled to a flying node, wherein an anode of the first diode circuit is coupled to the flying node and a cathode of the first diode circuit is coupled to the middle rail, wherein a cathode of the second diode circuit is coupled to the flying node and an anode of the second diode circuit is coupled to an output node (V SS ), and wherein a first node of the output capacitor is coupled to the output node and a second node of the output capacitor is coupled to the middle rail.
10. The integrated system of claim 9 further comprises:
the first diode circuit including a second current-source-biased P-channel MOSFET diode; and
the second diode circuit including a second current-source-biased N-channel MOSFET diode.