Offset-compensated active load and method
First Claim
Patent Images
1. An offset-compensated active load, comprising:
- a first transistor having a control electrode and first and second current carrying electrodes;
a second transistor having a control electrode and first and second current carrying electrodes, the first current carrying electrode of the first transistor coupled to the first current carrying electrode of the second transistor;
a first coupling device having a control terminal and first and second terminals, the control terminal coupled for receiving a first control signal, the first terminal coupled to the control electrode of the first transistor and the second terminal coupled to the second current carrying electrode of the first transistor;
a second coupling device having a control terminal and first and second terminals, the control terminal coupled for receiving a second control signal, the first terminal coupled to the control electrode of the second transistor and the second terminal coupled to the second current carrying electrode of the second transistor;
a first charge storage element having first and second terminals, the first terminal coupled to the control terminal of the first transistor and the second terminal switchably coupled to the second current carrying electrode of the first transistor;
a second charge storage element having first and second terminals, the first terminal coupled to the control terminal of the second transistor and the second terminal switchably coupled to the second current carrying electrode of the first transistor.
4 Assignments
0 Petitions
Accused Products
Abstract
In accordance with an embodiment, an offset-compensated active load includes a pair of transistors having control electrodes connected to their drain electrodes through coupling devices. The control electrodes of the transistors are connected to each other through a plurality of charge storage elements. In accordance with another embodiment, an offset current is generated in response to coupling input terminals of an input stage together. The offset current flows towards an active load which generates an offset voltage in response to the offset current. The offset voltage is stored in the plurality of charge storage devices of the offset-compensated active load.
26 Citations
20 Claims
-
1. An offset-compensated active load, comprising:
-
a first transistor having a control electrode and first and second current carrying electrodes; a second transistor having a control electrode and first and second current carrying electrodes, the first current carrying electrode of the first transistor coupled to the first current carrying electrode of the second transistor; a first coupling device having a control terminal and first and second terminals, the control terminal coupled for receiving a first control signal, the first terminal coupled to the control electrode of the first transistor and the second terminal coupled to the second current carrying electrode of the first transistor; a second coupling device having a control terminal and first and second terminals, the control terminal coupled for receiving a second control signal, the first terminal coupled to the control electrode of the second transistor and the second terminal coupled to the second current carrying electrode of the second transistor; a first charge storage element having first and second terminals, the first terminal coupled to the control terminal of the first transistor and the second terminal switchably coupled to the second current carrying electrode of the first transistor; a second charge storage element having first and second terminals, the first terminal coupled to the control terminal of the second transistor and the second terminal switchably coupled to the second current carrying electrode of the first transistor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 10)
-
-
8. An offset-compensated active load, comprising:
-
a first transistor having a control electrode and first and second current carrying electrodes; a second transistor having a control electrode and first and second current carrying electrodes, the first current carrying electrode of the first transistor coupled to the first current carrying electrode of the second transistor; a first coupling device having a control terminal and first and second terminals, the control terminal coupled for receiving a first control signal, the first terminal coupled to the control electrode of the first transistor and the second terminal coupled to the second current carrying electrode of the first transistor; a second coupling device having a control terminal and first and second terminals, the control terminal coupled for receiving a second control signal, the first terminal coupled to the control electrode of the second transistor and the second terminal coupled to the second current carrying electrode of the second transistor; a first charge storage element having first and second terminals, the first terminal coupled to the control electrode of the first transistor; a second charge storage element having first and second terminals, the first terminal coupled to the control electrode of the second transistor; a third coupling device having a control terminal coupled for receiving a third control signal, a first terminal coupled to the second current carrying electrode of the first transistor, and a second terminal coupled to the second terminal of the first charge storage element; a fourth coupling device having a control terminal coupled for receiving a fourth control signal, a first terminal coupled for receiving a first source of operating potential, and a second terminal commonly coupled to the second terminal of the first coupling device and to the second terminal of the first charge storage element; and
further including an input stage having an input terminal and first and second output terminals, the first output terminal coupled to the second current carrying electrode of the first transistor and the second output terminal coupled to the second current carrying electrode of the second transistor. - View Dependent Claims (9)
-
-
11. A method of operating an active load to compensate for offset in a circuit, comprising:
-
providing the active load, wherein the active load comprises a first transistor having a gate, a drain, and a source, a second transistor having a gate, a drain, and a source, a first switch having a control terminal and first and second terminals, a second switch having a control terminal and first and second terminals, a third switch having a control terminal and first and second terminals, a first capacitor having first and second terminals, and a second capacitor having first and second terminals, the sources of the first and second transistors coupled together, the gate of the first transistor coupled to the first terminals of the first switch and the first capacitor, the gate of the second transistor coupled to the first terminals of the second switch and the second capacitor, the second terminal of the first switch coupled to the drain of the first transistor and the first terminal of the third switch, the second terminal of the second switch coupled to the drain of the second transistor, and the second terminals of the first and second capacitors coupled together and to the second terminal of the third switch; generating an offset current in response to coupling input terminals of an input stage together, closing the first and second switches and opening the third switch, wherein the first and second capacitors are electrically decoupled from the drain of the first transistor and the offset current flows towards the active load; generating an offset compensation voltage in response to the offset current; and storing the offset compensation voltage in the first and second capacitors. - View Dependent Claims (12, 13, 14)
-
-
15. A method of compensating for offset in a circuit, comprising:
-
providing an active load having first and second transistors, first and second switches, and a plurality of charge storage elements, the first and second transistors each having a control electrode and first and second current carrying electrodes and each charge storage element of the plurality of charge storage elements having first and second terminals, the control electrode of the first transistor coupled to the control electrode of the second transistor through the plurality of charge storage elements, wherein the second terminals of first and second charge storage elements of the plurality of charge storage elements are coupled together at a first node; operating the active load in a first operating mode, wherein in the first operating mode, the control electrode of the first transistor is coupled to the first current carrying electrode of the first transistor at a second node and the control electrode of the second transistor is coupled to the first current carrying electrode of the second transistor at a third node; and operating the active load in a second operating mode, wherein in the second operating mode, the first node is decoupled from the first current carrying electrode of the first transistor and the control electrode of the second transistor is decoupled from the first current carrying electrode of the second transistor. - View Dependent Claims (16, 17, 18, 19, 20)
-
Specification