Low supply Class AB output amplifier
View Patent ↗An apparatus is provided which comprises: a differential input amplifying stage including a current source and a first node; a first matched pair of transistors coupled to the first node, wherein one of the transistors of the first matched pair is coupled to an output node of a driving stage; a second matched pair of transistors coupled to a second node to bias the second matched pair of transistors, wherein one of the transistors of the second matched pair of transistors is coupled to the output node of the driving stage, and wherein the second node is to be charged according to a first bias of the current source; and a resistive device coupled to the first and second nodes.
1. An apparatus comprising:
an integrator;
an analog-to-digital converter (ADC) coupled to an output of the integrator, wherein the ADC comprises a class AB amplifier having class AB biasing, wherein the AB amplifier comprises a differential amplifier stage and a current sense circuitry coupled to the differential amplifier stage; and
a digital-to-analog converter (DAC) coupled to the ADC and the integrator,
wherein the differential amplifier stage comprises a differential input amplifier having n-type devices, and
wherein the current sensing circuitry is to regulate an output quiescent current of the n-type devices.
2. The apparatus of claim 1 comprises a filter coupled to an input of the integrator.
3. The apparatus of claim 2 comprises a mixer coupled to the filter.
4. The apparatus of claim 3 comprises a low-noise-amplifier (LNA) coupled to the mixer.
5. The apparatus of claim 4 comprises an antenna coupled to an input of the LNA.
6. The apparatus of claim 1 , wherein the class AB amplifier comprises a resistor or a resistive device to level-shift an AC signal from an output of the differential input amplifier.
7. The apparatus of claim 1 , wherein the class AB amplifier comprises p-type devices for its output stage.
8. The apparatus of claim 7 comprises a common mode feedback loop to regulate quiescent current of the p-type devices.
9. The apparatus of claim 1 , wherein the differential amplifier stage includes a stack of three transistors including a current source between a supply node and a ground node.
10. The apparatus of claim 9 , wherein the class AB amplifier comprises: a current sensor coupled to a driving stage, together coupled to the differential amplifier stage, and wherein the current sensor and the driving stage have no more than two transistors in a stack between the supply node and the ground node.
11. A system apparatus comprising:
an antenna;
an integrated circuit (IC) coupled to the antenna, wherein the IC includes:
a first integrator;
a first analog-to-digital converter (ADC) coupled to an output of the first integrator, wherein the first ADC comprises a class AB amplifier having class AB biasing, wherein the AB amplifier comprises a differential amplifier stage and a current sense circuitry coupled to the differential amplifier stage; and
a first digital-to-analog converter (DAC) coupled to the first ADC and the first integrator;
a second integrator;
a second ADC coupled to an output of the second integrator, wherein the second ADC comprises a class AB amplifier having class AB biasing; and
a second DAC coupled to the second ADC and the second integrator; and
a memory coupled to the IC.
12. The system of claim 11 , wherein the IC comprises:
a first filter coupled to an input of the first integrator; and
a second filter coupled to an input of the second integrator.
13. The system of claim 12 , wherein the IC comprises:
a first mixer coupled to the first filter; and
a second mixer coupled to the second filter, wherein the first mixer is to receive a first local oscillation signal, and wherein the second mixer is to receive a second local oscillation signal which is phase-shifted relative to the first local oscillating signal.
14. The system of claim 13 , wherein the IC comprises a low-noise amplifier (LNA) coupled to the first and second mixers, and coupled to the antenna.
15. The system of claim 11 , wherein the differential amplifier stage comprises a differential input amplifier including n-type devices, wherein the current sensing circuitry is to regulate an output quiescent current of the n-type devices; and wherein the class AB amplifiers comprises:
a resistor or resistive device to level-shift an AC signal from an output of the differential input amplifier.
16. An apparatus comprising:
a differential input amplifier including a current source and a first node;
a matched pair of devices coupled to the first node, wherein one of the devices of the matched pair is coupled to an output node of a driving circuitry; and
a resistive device coupled to the first node.
17. The apparatus of claim 16 , wherein the matched pair is a first matched pair, and wherein apparatus comprises:
a second matched pair of device coupled to a second node to bias the second matched pair of devices, wherein one of the devices of the second matched pair of devices is coupled to the output node of the driving circuitry.
18. The apparatus of claim 17 , wherein the second node is to be charged according to a first bias of the current source, and wherein the resistive device is coupled to the second node.