Precision rectifier circuit for high-density, low-power implantable medical device
A precision voltage rectifier comprises a source voltage input and a voltage reference. The rectifier comprises switching elements that, according to the sign of the source signal, change the connections to the inputs of a differential difference amplifier that is connected as a voltage inverter. Embodiments of the invention are fully-integrated and CMOS compatible with high-input impedance such that the invention can be operated in low-power situations. A preferred application involves the integration of several similar circuits in a high-density, low-power implantable medical device. Particular embodiments of the invention can be used to rectify nerve signals collected by electrodes for use in a system for manipulating a prosthetic device.
1. A voltage rectifying circuit comprising:
a source signal input coupled to a first input of a polarity judgment circuit, to a first input of a first switch set and to a first input of a second switch set;
a reference signal input coupled to a second input of the polarity judgment circuit, to a second input of the first switch set, to a second input of the second switch set and to a second non-inverting input of a DDA;
the DDA having an output connected to a second inverting input of the DDA;
the polarity judgment circuit having an output connected to the input of an inverter and to a control input of the first switch set;
the inverter having an output connected to a control input of the second switch set;
the first switch set having a first output connected to a first non-inverting input of the DDA; and a second output connected to a first inverting input of the DDA; and
the second switch set having a first output connected to the first non-inverting input of the DDA, and a second output connected to the first inverting input of the DDA.
2. A voltage rectifying circuit in accordance with claim 1 , wherein the DDA comprises: current sources implemented using a cascode technique.
3. A voltage rectifying circuit in accordance with claim 2 , wherein the polarity judgment circuit comprises a comparator.
4. A voltage rectifying circuit in accordance with claim 1 , wherein the polarity judgment circuit comprises a comparator.
5. A voltage rectifying circuit comprising:
a source signal input coupled to a first input of a polarity judgment circuit, to a source of a first switching element and to a source of a third switching element;
a reference signal input coupled to a second input of the polarity judgment circuit, to a source of a second switching element, to a source of a fourth switching element and to a second non-inverting input of a DDA;
the DDA having an output connected to a second inverting input of the DDA;
the polarity judgment circuit having an output connected to the input of an inverter, to a gate of the second switching element and to a gate of the third switching element;
the inverter having an output connected to a gate of the first switching element and to a gate of the fourth switching element;
the first switching element having a drain connected to a first non-inverting input of the DDA;
the second switching element having a drain connected to the first non-inverting input of the DDA;
the third switching element having a drain connected to a first inverting input of the DDA; and, the fourth switching element having a drain connected to the first inverting input of the DDA.
6. A voltage rectifying circuit according to claim 5 , wherein the switching elements are CMOS transistors.
7. A voltage rectifying circuit in accordance with claim 6 , wherein the DDA comprises:
current sources implemented using a cascode technique.
8. A voltage rectifying circuit in accordance with claim 7 , wherein the polarity judgment circuit comprises a comparator.
9. A voltage rectifying circuit according to claim 5 , wherein the source of the first switching element is connected to the reference signal.
10. A voltage rectifying circuit according to claim 5 , wherein the source of the third switching element is connected to the reference signal.