Capacitor weighted segmentation buffer
A capacitor weighted segmentation buffer includes a push-pull buffer circuit and a plurality of capacitors. The capacitors include a first capacitor having a first terminal coupled to a control terminal of the first transistor and a second terminal arranged to receive a first input signal; a second capacitor having a first terminal coupled to a control terminal of the second transistor and a second terminal arranged to receive the first input signal; a third capacitor having a first terminal coupled to the control terminal of the first transistor and a second terminal arranged to receive a second input signal; and a fourth capacitor having a first terminal coupled to the control terminal of the second transistor and a second terminal arranged to receive the second input signal.
1. A capacitor weighted segmentation buffer comprising:
a push-pull buffer circuit, comprising:
a first transistor, having a control terminal, a first connection terminal, and a second connection terminal; and
a second transistor, having a control terminal, a first connection terminal, and a second connection terminal, wherein the second connection terminal of the first transistor and the second connection terminal of the second transistor are source terminals coupled to an output node of the capacitor weighted segmentation buffer; and
a plurality of capacitors, comprising:
a first capacitor, having a first terminal coupled to the control terminal of the first transistor, and a second terminal arranged to receive a first input signal of the capacitor weighted segmentation buffer;
a second capacitor, having a first terminal coupled to the control terminal of the second transistor, and a second terminal arranged to receive the first input signal of the capacitor weighted segmentation buffer;
a third capacitor, having a first terminal coupled to the control terminal of the first transistor, and a second terminal arranged to receive a second input signal of the capacitor weighted segmentation buffer; and
a fourth capacitor, having a first terminal coupled to the control terminal of the second transistor, and a second terminal arranged to receive the second input signal of the capacitor weighted segmentation buffer;
wherein each of the first capacitor and the second capacitor has a first capacitance value, and each of the third capacitor and the fourth capacitor has a second capacitance value different from the first capacitance value.
2. The capacitor weighted segmentation buffer of claim 1 , wherein the plurality of capacitors further comprise:
a fifth capacitor, having a first terminal coupled to the control terminal of the first transistor, and a second terminal arranged to receive a third input signal of the capacitor weighted segmentation buffer; and
a sixth capacitor, having a first terminal coupled to the control terminal of the second transistor, and a second terminal arranged to receive the third input signal of the capacitor weighted segmentation buffer;
wherein each of the fifth capacitor and the sixth capacitor has a third capacitance value different from any of the first capacitance value and the second capacitance value.
3. The capacitor weighted segmentation buffer of claim 1 , further comprising:
a switch circuit, arranged to support a first configuration and a second configuration, wherein the push-pull buffer circuit operates in a reset mode when the switch circuit has the first configuration, and operates in a buffer mode when the switch circuit has the second configuration.
4. The capacitor weighted segmentation buffer of claim 3 , further comprising:
a replica bias circuit, arranged to generate and output a first bias voltage to the control terminal of the first transistor and generate and output a second bias voltage to the control terminal of the second transistor when the push-pull buffer circuit operates in the reset mode.
5. The capacitor weighted segmentation buffer of claim 4 , wherein the replica bias circuit is disconnected from the push-pull buffer circuit when the push-pull buffer circuit operates in the buffer mode.
6. The capacitor weighted segmentation buffer of claim 3 , wherein the first input signal is delivered to the second terminal of the first capacitor and the second terminal of the second capacitor when the push-pull buffer circuit operates in the buffer mode; and the second input signal is delivered to the second terminal of the third capacitor and the second terminal of the fourth capacitor when the push-pull buffer circuit operates in the buffer mode.
7. The capacitor weighted segmentation buffer of claim 6 , wherein the first input signal is disconnected from the first capacitor and the second capacitor and the second input signal is disconnected from the third capacitor and the fourth capacitor when the push-pull buffer circuit operates in the reset mode.
8. The capacitor weighted segmentation buffer of claim 3 , wherein a common-mode voltage is delivered to the second terminal of the first capacitor, the second terminal of the second capacitor, the second terminal of the third capacitor and the second terminal of the fourth capacitor when the push-pull buffer circuit operates in the reset mode.
9. The capacitor weighted segmentation buffer of claim 1 , wherein the capacitor weighted segmentation buffer is integrated with a digital-to-analog converter (DAC).
10. The capacitor weighted segmentation buffer of claim 9 , wherein the DAC comprises:
a resistor digital-to-analog converter (RDAC), arranged to provide a plurality of reference voltage levels; and
a capacitor digital-to-analog converter (CDAC), wherein the plurality of capacitors are used by the CDAC, and the plurality of reference voltage levels are provided to the CDAC.
11. The capacitor weighted segmentation buffer of claim 10 , wherein the CDAC comprises:
the first capacitor;
the third capacitor;
the second capacitor;
the fourth capacitor;
a first decoder, arranged to select and output one of the plurality of reference voltage levels as the first input signal according to a first segment of a digital code of the DAC; and
a second decoder, arranged to select and output one of the plurality of reference voltage levels as the second input signal according to a second segment of the digital code of the DAC.
12. The capacitor weighted segmentation buffer of claim 11 , wherein the digital code is one input data of a neural network.
13. The capacitor weighted segmentation buffer of claim 9 , wherein the output node of the capacitor weighted segmentation buffer is coupled to an analog compute-in-memory (ACIM) circuit.
14. The capacitor weighted segmentation buffer of claim 1 , wherein the capacitor weighted segmentation buffer is an analog compute-in-memory (ACIM) buffer.
15. The capacitor weighted segmentation buffer of claim 14 , wherein each of the first input signal and the second input signal is generated from an ACIM circuit, and the ACIM circuit comprises:
a plurality of processing circuits, comprising:
a first processing circuit, arranged to generate and output the first input signal according to a plurality of analog inputs and first segments of a plurality of stored data; and
a second processing circuit, arranged to generate and output the second input signal according to the plurality of analog inputs and second segments of the plurality of stored data.
16. The capacitor weighted segmentation buffer of claim 15 , wherein each of the plurality of processing circuits is a multiply-accumulate (MAC) circuit.
17. The capacitor weighted segmentation buffer of claim 15 , wherein each of the analog inputs corresponds to one input data of a neural network.