Hybrid differential amplifier and hybrid differential amplification method

Abstract

This invention provides a hybrid differential amplifier with high linearity. [Solution] The hybrid differential amplifier according to the present invention, which generates a differential output signal based on a differential input signal having a fundamental frequency, includes a first amplifier configured as an inductive switching converter and a second amplifier configured as another type of amplifier. The first and second amplifiers generate first and second output signals of a differential output signal, respectively, based on first and second input signals of a differential input signal. One of the first or second amplifiers further generates the first or second output signal based on feedback, thereby the differential output signal is linearly related to the differential input signal. The other amplifier performs a quantization process on the first or second input signal, thereby the second output signal includes a step wave related to the fundamental frequency. The quantization process includes generating a quantized output signal based on the first or second input signal and at least one threshold level.

Description

Technical Field

[0001] (Cross - reference to related applications) The present invention claims priority to TW113143733 (filed on November 14, 2024, access code: 3AB6) and claims priority to US19 / 173,860 (filed on April 9, 2025, access code: 1671).

[0002] The present invention relates to a hybrid differential amplifier, and more particularly to a hybrid differential amplifier having high linearity. The present invention also relates to a method for controlling the aforementioned hybrid differential amplifier.

Background Art

[0003] FIG. 1A shows a simplified block diagram of a prior - art hybrid differential amplifier. The prior - art hybrid differential amplifier includes a first amplification circuit and a second amplification circuit. The first amplification circuit and the second amplification circuit are configured to amplify a first input signal Vip and a second input signal Vin of a differential input signal, respectively, and generate corresponding first output signal Vop and second output signal Von. The first amplification circuit is configured as a switching class - D converter, and the second amplification circuit is configured as an analog amplifier. Compared with a conventional pure class - D amplifier, in the prior - art design, one LC filter is eliminated. However, since the second amplification circuit is implemented as an analog amplifier, the overall conversion efficiency and linearity of the differential amplifier are reduced.

[0004] Figure 1B shows the waveform diagram of a conventional hybrid differential amplifier in operation. As shown in Figure 1B, a drawback of the conventional technology is that the delay time Td between the first output signal Vop and the second output signal Von can cause the first output signal Vop to exceed the lower limit LML or upper limit LMU of the supply voltage and enter a saturated state, potentially resulting in nonlinear distortion between the first output signal Vop and the differential output signal Vod. This is shown at the intersection of the differential output signal Vod and the second output signal Von', where the second output signal Von' represents the waveform of the second output signal Von aligned in the same time domain as the differential output signal Vod. [Overview of the project] [Problems that the invention aims to solve]

[0005] Taking the above into consideration, and in order to overcome the shortcomings of the prior art, the present invention provides a hybrid differential amplifier with high linearity. Due to a quantization operation performed by either the first or second amplifier, the second output signal Von includes a step wave having three levels. The duration of the intermediate level of the three levels is longer than the delay time between the first output signal Vop and the second output signal Von, thereby generating a differential output signal with high linearity. [Means for solving the problem]

[0006] From one perspective, the present invention provides a hybrid differential amplifier configured to generate a differential output signal based on a differential input signal to drive a load. The differential input signal has a fundamental frequency, and the hybrid differential amplifier includes a first amplifier and a second amplifier. The first amplifier is configured as an inductive switching converter and is configured to switch inductors by performing pulse-width modulation (PWM) conversion based on a first input signal of a differential input signal to generate a first output signal of a differential output signal. The second amplifier is configured to generate a second output signal of a differential output signal based on a second input signal of a differential input signal, and is configured as a different type of amplifier from an inductive switching converter. Either the first or second amplifier is further configured to generate a first or second output signal based on feedback from the differential output signal, such that the differential output signal is linearly related to the differential input signal. The other of the first or second amplifier is further configured to perform a quantization operation on the first or second input signal such that the second output signal includes a step wave related to the fundamental frequency, the step wave including at least three quantized output levels. The quantization operation includes generating a quantized output signal based on a first or second input signal and at least one quantization threshold level, such that the second output signal includes a step wave.

[0007] In one embodiment, at least three quantized output levels include a first step level, a second step level, and a ground level. The second step level is lower than the first step level and higher than the ground level. The duration of the second step level is longer than the delay time between the first and second output signals, such that the distortion level of the differential output signal is below a predetermined level.

[0008] In one embodiment, the first step level corresponds to the voltage level of the supply voltage, and the second step level corresponds to the divided voltage level of the supply voltage.

[0009] In one embodiment, the second amplifier includes a quantization control circuit coupled to a second input signal and a selection circuit coupled between the quantization control circuit and the second output signal. The quantization operation includes a quantization control circuit configured to generate a quantization control signal based on a second input signal and at least one quantization threshold level, and a selection circuit configured to select a first step level, a second step level, or a ground level based on the quantization control signal to generate a quantized output signal. The quantized output signal corresponds to the second output signal.

[0010] In one embodiment, the first amplifier includes a loop filter circuit configured to generate a loop filter signal by performing a linear integral based on the difference between a differential output signal and a differential input signal; a PWM circuit configured to generate a PWM output signal based on a comparison between the loop filter signal and a triangular wave; and a switching power stage circuit configured to generate a first output signal by switching inductors based on the PWM output signal. The first amplifier performs feedback control so that the first output signal includes a superposition of the first input signal and a step wave.

[0011] In one embodiment, the second amplifier is configured as a linear amplifier operating in the continuous-time domain and includes a quantization circuit coupled to the second input signal and an amplification stage circuit coupled between the quantization circuit and the second output signal. The quantization operation includes a quantization circuit configured to generate a quantized output signal based on a second input signal and at least one quantization threshold level, wherein the quantized output signal includes a square wave or a step wave associated with each fundamental frequency, and an amplification stage circuit configured to linearly amplify the quantized output signal to generate a second output signal. A square wave includes two levels corresponding to a first step level and a ground level, while a step wave includes three levels corresponding to a first step level, a second step level, and a ground level.

[0012] In one embodiment, the first amplifier includes a loop filter circuit configured to generate a loop filter signal by performing a linear integral based on the difference between a differential output signal and a differential input signal; a PWM circuit configured to generate a PWM output signal based on a comparison between the loop filter signal and a triangular wave; and a switching power stage circuit configured to generate a first output signal by switching inductors based on the PWM output signal. The first amplifier performs feedback control so that the first output signal includes a superposition of the first input signal and a step wave.

[0013] In one embodiment, if the quantized output signal includes a square wave related to the fundamental frequency, the amplification stage circuit includes a Class B amplifier or a Class AB amplifier. A Class B amplifier includes a first high-side transistor and a first low-side transistor. The gates of the first high-side transistor and the first low-side transistor are coupled to each other and coupled to a quantized output signal. The first high-side transistor and the first low-side transistor are connected in series between the supply voltage and the ground potential to generate a second output signal, the duration of which is related to the turn-on threshold of the first high-side transistor and the turn-on threshold of the first low-side transistor. A Class AB amplifier includes a second high-side transistor, a second low-side transistor, and a level shifter. The first and second terminals of the level shifter are coupled to the gates of the second high-side transistor and the second low-side transistor, respectively, to maintain the voltage difference between the gates of the second high-side transistor and the second low-side transistor. The input terminal of the level shifter is coupled to the quantized output signal to control the voltages at the first and second terminals. The second high-side transistor and the second low-side transistor are connected in series between the supply voltage and ground potential to generate a second output signal. The duration of the second step level is related to the turn-on threshold of the second high-side transistor, the turn-on threshold of the second low-side transistor, and the offset level of the level shifter. The supply voltage has a first step level, the ground potential corresponds to the ground level, and the offset level is positively correlated with the voltage difference.

[0014] In one embodiment, if the quantized output signal includes a step wave related to the fundamental frequency, the amplification stage circuit includes a Class AB amplifier. A Class AB amplifier includes a high-side transistor, a low-side transistor, and a level shifter. The first and second terminals of the level shifter are coupled to the gates of the high-side and low-side transistors, respectively, to maintain the voltage difference between the gates of the high-side and low-side transistors. The input terminal of the level shifter is coupled to the quantized output signal to control the voltages at the first and second terminals. The high-side and low-side transistors are connected in series between the supply voltage and ground potential to generate a second output signal. The duration of the second step level is related to the turn-on threshold of the high-side transistor, the turn-on threshold of the low-side transistor, and the offset level of the level shifter. The supply voltage has a first step level, the ground potential corresponds to the ground level, and the offset level is positively correlated with the voltage difference.

[0015] In one embodiment, the first amplifier includes a preprocessing circuit configured to perform preprocessing operations based on a first or second input signal to generate a preprocessed output signal; a PWM circuit configured to generate a PWM output signal based on a comparison of the preprocessed output signal with a triangular wave; and a switching power stage circuit configured to switch inductors based on the PWM output signal to generate a first output signal. The preprocessing operation includes performing a quantization operation based on a first or second input signal and at least one quantization threshold level to generate a quantized output signal, and superimposing the quantized output signal with the first input signal to generate a preprocessed output signal. The quantized output signal includes a step wave, which includes a first step level, a second step level, and a ground level.

[0016] In one embodiment, the second amplifier includes a loop filter circuit configured to generate a loop filter signal by performing a linear integral based on the difference between a differential output signal and a differential input signal; a gain stage circuit configured to generate a gain output signal by linearly amplifying the loop filter signal; and an amplification stage circuit configured to generate a second output signal by linearly amplifying the gain output signal. The second amplifier performs feedback control so that the second output signal contains a step wave.

[0017] From another perspective, the present invention provides a hybrid differential amplification method configured to generate a differential output signal based on a differential input signal to drive a load. The differential input signal has a fundamental frequency, and the hybrid differential amplification method includes the following steps: A step of generating a first output signal of a differential output signal by performing a PWM (pulse width modulation) conversion based on a first input signal of a differential input signal. A step of generating a second output signal of a differential output signal based on a second input signal of a differential input signal. The second output signal is generated in a manner different from PWM conversion. One of the first output signal or the second output signal is further generated based on feedback from the differential output signal such that the differential output signal is linearly related to the differential input signal. The other of the first output signal or the second output signal is further generated based on the quantization operation of the first input signal or the second input signal such that the second output signal includes a staircase wave related to the fundamental frequency, and the staircase wave includes at least three quantized output levels. The quantization operation includes generating a quantized output signal based on the first input signal or the second input signal and at least one quantization threshold level such that the second output signal includes a staircase wave.

[0018] The objectives, technical details, features, and effects of the present invention will be better understood with reference to the drawings and in connection with the following detailed description of the embodiments.

Brief Description of the Drawings

[0019] [Figure 1A] It is a simplified block diagram of a conventional hybrid differential amplifier. [Figure 1B] It is a waveform diagram of the operation of a conventional hybrid differential amplifier. [Figure 2A] It is a circuit block diagram of a hybrid differential amplifier according to an embodiment of the present invention. [Figure 2B] It is a circuit block diagram of a hybrid differential amplifier according to another embodiment of the present invention. [Figure 3A] It is a circuit block diagram of a hybrid differential amplifier corresponding to FIG. 2A according to an embodiment of the present invention. [Figure 3B] It is a circuit block diagram of a hybrid differential amplifier corresponding to FIG. 2A according to an embodiment of the present invention. [Figure 4A] It is a circuit block diagram of a second amplifier corresponding to the hybrid differential amplifier shown in FIG. 3A according to an embodiment of the present invention. [Figure 4B]This is a circuit block diagram of a second amplifier corresponding to the hybrid differential amplifier shown in Figure 3A, according to an embodiment of the present invention. [Figure 5] This is a circuit block diagram of a first amplifier corresponding to the hybrid differential amplifier shown in Figure 2A, according to an embodiment of the present invention. [Figure 6] This is a schematic circuit diagram of a second amplifier corresponding to the hybrid differential amplifier shown in Figure 3B, according to an embodiment of the present invention. [Figure 7] This is a waveform diagram of a hybrid differential amplifier according to an embodiment of the present invention. [Figure 8] This is a schematic circuit diagram of a second amplifier corresponding to the hybrid differential amplifier shown in Figure 6, according to an embodiment of the present invention. [Figure 9] This is a schematic circuit diagram of a second amplifier corresponding to the hybrid differential amplifier shown in Figure 6, according to an embodiment of the present invention. [Figure 10] This is a schematic circuit diagram of a second amplifier corresponding to the hybrid differential amplifier shown in Figure 6, according to an embodiment of the present invention. [Figure 11] This is a schematic circuit diagram of a second amplifier corresponding to the hybrid differential amplifier shown in Figure 6, according to an embodiment of the present invention. [Figure 12A] This is a schematic circuit diagram of the second amplifier of a hybrid differential amplifier according to an embodiment of the present invention. [Figure 12B] This is a schematic circuit diagram of the second amplifier of a hybrid differential amplifier according to an embodiment of the present invention. [Figure 13] These are waveform diagrams of the quantized output signals corresponding to Figures 12A and 12B, according to two embodiments of the present invention. [Figure 14] This is a schematic circuit diagram of a second amplifier corresponding to the hybrid differential amplifier shown in Figure 12A, according to an embodiment of the present invention. [Figure 15A] This is a schematic diagram of an amplification stage circuit corresponding to the second amplifier in Figure 12B, according to a specific embodiment of the present invention. [Figure 15B] This is a schematic diagram of the amplification stage circuit corresponding to the second amplifier in Figures 12A and 12B, according to a specific embodiment of the present invention. [Figure 16] This is a circuit block diagram of a hybrid differential amplifier corresponding to Figure 2B, according to an embodiment of the present invention. [Figure 17] This is a circuit block diagram of the pre-processing circuit corresponding to the first amplifier in Figure 16, according to one embodiment of the present invention. [Modes for carrying out the invention]

[0020] The drawings referenced throughout this description of the present invention are for illustrative purposes only to illustrate the relationship between circuits and signal waveforms and are not drawn to the actual scale of the circuit size and signal amplitude and frequency.

[0021] Figure 2A shows a circuit block diagram of a hybrid differential amplifier according to an embodiment of the present invention. Figure 2B shows a circuit block diagram of a hybrid differential amplifier according to another embodiment of the present invention. As shown in Figures 2A and 2B, the hybrid differential amplifier 20A or 20B of the present invention is configured to generate a differential output signal Vod based on a differential input signal Vid to drive a load, the differential input signal Vid having a fundamental frequency Ff. In one embodiment, each of the hybrid differential amplifiers 20A or 20B has a first amplifier 1000 and a second amplifier 2000. In one embodiment, the first amplifier 1000 is configured as an inductive switching converter and is configured to switch an inductor L by performing pulse width modulation (PWM) conversion based on a first input signal Vip of the differential input signal Vid to generate a first output signal Vop of the differential output signal Vod. In one embodiment, the second amplifier 2000 is configured to generate a second output signal Von of the differential output signal Vod based on a second input signal Vin of the differential input signal Vid. In one embodiment, the second amplifier 2000 is configured as a different type of amplifier than an inductive switching converter. Specifically, in this embodiment, the first amplifier 1000 is configured as a Class D amplifier, and the second amplifier 2000 may be configured as a Class B or Class AB amplifier, which will be described in detail later.

[0022] In one embodiment, the first input signal Vip and the first output signal Vop are, for example, a positive input signal and a positive output signal, respectively, and the second input signal Vin and the second output signal Von are, for example, a negative input signal and a negative output signal, respectively, with the positive and negative input signals being complementary. In one embodiment, the differential input signal Vid refers to the difference signal between the first input signal Vip and the second input signal Vin, and the differential output signal Vod refers to the difference signal between the first output signal Vop and the second output signal Von.

[0023] In one embodiment, either the first amplifier 1000 or the second amplifier 2000 is further configured to generate a first output signal Vop or a second output signal Von based on feedback from the differential output signal Vod, such that the differential output signal Vod is linearly related to the differential input signal Vid. In one embodiment, the other of the first amplifier 1000 or the second amplifier 2000 is further configured to perform a quantization operation on a first input signal Vip or a second input signal Vin, such that the second output signal Von includes a step wave related to a fundamental frequency Ff, the step wave including at least three quantized output levels (described in detail later). In a particular embodiment, as shown in Figure 2A, the first amplifier 1000 includes a feedback loop, and the second amplifier 2000 is configured to perform a quantization operation on a second input signal Vin. In another specific embodiment, as shown in Figure 2B, the second amplifier 2000 includes a feedback loop, and the first amplifier 1000 is configured to perform a preprocessing operation on a first input signal Vip, the preprocessing operation including a quantization operation in one embodiment. In one embodiment, the quantization operation includes generating a quantized output signal based on the first input signal Vip or the second input signal Vin and at least one quantization threshold level, such that the second output signal Von includes a step wave. Details of the preprocessing operation and the quantization operation will be described later.

[0024] Figures 3A and 3B show circuit block diagrams of hybrid differential amplifiers corresponding to Figure 2A, according to two embodiments of the present invention. In one embodiment, as shown in the hybrid differential amplifier 30A of Figure 3A, the first amplifier 1100 includes a digital-to-analog converter 110, a loop filter circuit 120, a PWM circuit 140, a logic / level shift circuit 150, and a switching power stage circuit 160. In one embodiment, the hybrid differential amplifier 30A is configured to generate a differential output signal Vod based on a digital input signal Din, and the digital-to-analog converter 110 is configured to convert the digital input signal Din into a first input signal Vip and a second input signal Vin in the analog domain. In one embodiment, the switching power stage circuit 160 and inductor L are coupled to a switching node where a switching node signal LXp is generated.

[0025] In one embodiment, the loop filter circuit 120 is configured to generate a loop filter signal Vftr by performing a linear integral based on the difference between a differential output signal Vod and a differential input signal Vid. In this embodiment, the differential output signal Vod refers to the difference signal between a first output signal Vop and a second output signal Von, or the difference signal between a switching node signal LXp and a second output signal Von. In one embodiment, the PWM circuit 140 is configured to generate a PWM output signal SPW based on a comparison between the loop filter signal Vftr and a triangular wave VTR1. In one embodiment, the PWM circuit 140 may be implemented as a comparator. The logic / level shift circuit 150 is configured to generate a drive signal based on the PWM output signal SPW and to shift the voltage level of the drive signal to the drive level required by the switching power stage circuit 160. The switching power stage circuit 160 is configured to switch the inductor L based on the drive signal generated by the logic / level shift circuit 150 to generate a first output signal Vop. In this embodiment, the first amplifier 1100 performs feedback control so that the first output signal Vop includes a superposition of the first input signal Vip and a step wave.

[0026] In one embodiment, as shown in Figure 3A, the second amplifier 2100 includes a quantization circuit 210 and an amplification stage circuit 220. In this embodiment, the quantization operation includes the quantization circuit 210 being configured to generate a quantized output signal QON based on a digital input signal Din, and the amplification stage circuit 220 being configured to linearly amplify the quantized output signal QON to generate a second output signal Von, which will be described in detail later.

[0027] In another embodiment, as shown in Figure 3B, the second amplifier 2200 includes a quantization control circuit 230 and a selection circuit 240. In this embodiment, the quantization control circuit 230 is coupled to a digital input signal Din, and the selection circuit 240 is coupled between the quantization control circuit 230 and a second output signal Von. In one embodiment, the quantization operation includes the quantization control circuit 230 being configured to generate a quantization control signal QS based on the digital input signal Din, and the selection circuit 240 being configured to generate a second output signal Von based on the quantization control signal QS, which will be described in detail later. Note that for other details of the hybrid differential amplifier 30B in Figure 3B, refer to the description in Figure 3A.

[0028] Figures 4A and 4B show circuit block diagrams of second amplifiers corresponding to the hybrid differential amplifier shown in Figure 3A, according to two embodiments of the present invention. The second amplifiers shown in Figures 4A and 4B are similar to the second amplifier 2100 in Figure 3A. In one embodiment, as shown in Figure 4A, the second amplifier 2100A further includes an analog-to-digital converter 250. The analog-to-digital converter 250 is configured to convert a first input signal Vip or a second input signal Vin to produce a digital output signal Dout. In this embodiment, the quantization circuit 210A of the second amplifier 2100A performs a quantization operation in the digital domain to produce a quantized output signal QON. In another embodiment, as shown in Figure 4B, the quantization circuit 210B of the second amplifier 2100B is configured to produce a quantized output signal QON based on a first input signal Vip or a second input signal Vin in the analog domain. For further details regarding the operation of Figures 4A and 4B, please refer to the description of Figure 3A.

[0029] It should be noted that the second amplifier 2200 in Figure 3B can instead be configured as the second amplifier 2100A or 2100B shown in Figure 4A or Figure 4B.

[0030] Figure 5 shows a circuit block diagram of a first amplifier corresponding to the hybrid differential amplifier shown in Figure 2A, according to an embodiment of the present invention. In one embodiment, as shown in Figure 5, the first amplifier 1105 further includes a superposition circuit 130. The superposition circuit 130 is configured to generate a processed loop filter signal Vftr' based on the superposition of a loop filter signal Vftr and an associated signal f_Von related to a second output signal Von. For further details of the operation of the first amplifier 1105, see the description in Figure 3A. Note that the first amplifier in Figures 3A and 3B can be configured as the first amplifier 1105 in Figure 5.

[0031] Figure 6 shows a schematic circuit diagram of a second amplifier corresponding to the hybrid differential amplifier of Figure 3B, according to an embodiment of the present invention. The second amplifier 2206 in Figure 6 is one embodiment of the second amplifier 2200 shown in Figure 3B. As shown in Figure 6, in one embodiment, the selection circuit 240 includes a multiplexer 40. In this embodiment, the quantization processing operation described above includes the quantization control circuit 230 being configured to generate a quantization control signal QS based on a digital input signal Din (or a second input signal Vin) and at least one quantization threshold level, and the selection circuit 240 (i.e., the multiplexer 40) being configured to select a first step level ST1, a second step level ST2, or a ground level GND based on the quantization control signal QS, and to generate a second output signal Von.

[0032] Please refer to both Figures 6 and 7. Figure 7 shows a waveform diagram of a hybrid differential amplifier according to an embodiment of the present invention. In one embodiment, based on the configuration shown in Figure 6, the second output signal Von may include a step wave related to the fundamental frequency Ff, and the step wave includes at least three quantized output levels. As shown in the waveform of the second output signal Von in Figure 7, in one embodiment, the at least three quantized output levels include a first step level ST1, a second step level ST2, and a ground level GND. In this embodiment, the second step level ST2 is lower than the first step level ST1 and higher than the ground level GND. In one embodiment, the duration TC of the second step level ST2 is longer than the delay time Td between the first output signal Vop and the second output signal Von such that the distortion level of the differential output signal Vod is below a predetermined level.

[0033] As shown in Figures 6 and 7, in certain embodiments, at least one quantization threshold level includes a lower quantization threshold level and a higher quantization threshold level. If the digital input signal Din is lower than the lower quantization threshold level, the selection circuit 240 selects the ground level GND based on the quantization control signal QS and generates a second output signal Von. If the digital input signal Din is higher than the lower quantization threshold level and lower than the higher quantization threshold level, the selection circuit 240 selects a second step level ST2 based on the quantization control signal QS and generates a second output signal Von. If the digital input signal Din is higher than the higher quantization threshold level, the selection circuit 240 selects a first step level ST1 based on the quantization control signal QS and generates a second output signal Von. In the above-described embodiment, the second output signal Von is a step wave having three quantized output levels. In other embodiments, if at least one quantization threshold level includes three or more quantization threshold levels, the at least three quantized output levels may include four or more quantized output levels, and the present invention may be extended accordingly.

[0034] It should be noted that the fundamental frequency Ff corresponds to the reciprocal of the time Tf of the differential output signal Vod. Furthermore, compared with the conventional waveform diagram shown in Figure 1B, it should be noted that the present invention utilizes a quantization operation such that the second output signal Von becomes a step wave having at least three levels, and the duration TC of the second step level ST2 is longer than the delay time Td. As a result, the zero-crossing point of the differential output signal Vod (solid line in the third waveform of Figure 7) coincides with the duration TC of the second step level ST2 (dashed line in the third waveform of Figure 7), allowing the first output signal Vop to remain between the lower limit LML and the upper limit LMU of the supply voltage. From one particular viewpoint, the duration TC of the second step level ST2 provides a safety device or time window that can absorb any delay-induced mismatch between Vop and Von, thus preventing any signal along the signal path of the hybrid differential amplifier from drifting into the nonlinear region (i.e., beyond LML or LMU). In other words, the signal Vop does not saturate, but is instead clamped to the lower LML or upper LMU limit, thus reducing the distortion level between the first output signal Vop and the differential output signal Vod. That is, the linearity between the first output signal Vop and the differential output signal Vod is improved. By appropriately selecting the duration TC, the distortion level can satisfy certain requirements, for example, to be lower than a certain level. In Figure 7, the dashed waveform of the second output signal Von' is the waveform of the second output signal Von in the same time domain as the differential output signal Vod. The aforementioned zero-crossing point refers to the intersection of the differential output signal Vod and its common-mode level.

[0035] Figures 8 to 11 show schematic circuit diagrams of second amplifiers corresponding to the hybrid differential amplifier shown in Figure 6, according to several embodiments of the present invention. The second amplifiers 2208 to 2211 in Figures 8 to 11 are specific embodiments of the second amplifier 2206 shown in Figure 6. As shown in Figures 8 to 11, the first step level ST1 corresponds to the voltage level of the supply voltage PVDD, and the second step level ST2 corresponds to the voltage level of the divided voltage of the supply voltage PVDD. The operation of the selection circuits 241 to 244 shown in Figures 8 to 11 will be described in detail below.

[0036] In one embodiment, as shown in Figure 8, the selection circuit 241 includes switches SW1 to SW3. Switches SW1 to SW3 are configured to select a supply voltage PVDD, another supply voltage PVDD1 (whose level can be a division of PVDD), or a ground level GND based on a quantization control signal QS to generate a second output signal Von.

[0037] The second amplifier 2209 in Figure 9 is similar to the second amplifier 2208 in Figure 8. In one embodiment, the selection circuit 242 in Figure 9 further includes a buffer 42. The buffer 42 is configured to linearly amplify the divided voltage PVDD1' of the supply voltage PVDD to generate the other supply voltage PVDD1.

[0038] The second amplifier 2210 in Figure 10 is similar to the second amplifier 2209 in Figure 9. In one embodiment, the selection circuit 243 in Figure 10 further includes n switches SW11~SW1n. One end of each switch SW11~SW1n is coupled to one of the n divided voltages PVDD_D1~PVDD_Dn of the supply voltage PVDD, and the other end is commonly coupled to the positive input terminal of the buffer 42 (where n is a positive integer). In one embodiment, the switches SW11~SW1n are configured to select one of the divided voltages PVDD_D1~PVDD_Dn based on a quantization control signal QS and input it to the buffer 42 to generate another supply voltage PVDD1. In this embodiment, the second output signal Von generated by the selection circuit 243 is a step wave containing more than three quantized output levels.

[0039] In one embodiment, as shown in Figure 11, the selection circuit 244 includes switches SW1 and SW3 and a plurality of switches SW21 to SW2n. In this embodiment, the plurality of switches SW21 to SW2n are each coupled to a plurality of system voltages VDD1 to VDDn. In one embodiment, switches SW1, SW21 to SW2n, and SW3 are configured to generate a second output signal Von by selecting at least one of the supply voltage PVDD, the plurality of system voltages VDD1 to VDDn, or the ground level GND based on a quantization control signal QS. In this embodiment, the second output signal Von generated by the selection circuit 244 is also a step wave containing three or more quantized output levels.

[0040] In the embodiments shown in Figures 10 and 11, by generating the second output signal Von as a multilevel step wave (including more than three quantized output levels), the zero-crossing point of the differential output signal Vod can intersect with more than two quantized output levels (step levels). Therefore, the first output signal Vop remains between the lower limit LML and the upper limit LMU of the supply voltage and does not saturate, thereby reducing the distortion level between the first output signal Vop and the differential output signal Vod. Furthermore, it should be noted that such saturation can occur at other nodes in the signal path. According to the present invention, these saturation phenomena that occurred in the prior art can be effectively avoided, thereby effectively reducing the distortion level between the first output signal Vop and the differential output signal Vod.

[0041] Figures 12A and 12B show schematic circuit diagrams of a second amplifier of a hybrid differential amplifier according to two embodiments of the present invention. As shown in Figure 12A, in one embodiment, the second amplifier 2112A is configured as a linear amplifier operating in the continuous-time domain. In this embodiment, the second amplifier 2112A includes a quantization circuit 211 and an amplification stage circuit 221. The quantization circuit 211 is coupled to a first input signal Vip or a second input signal Vin, and the amplification stage circuit 221 is coupled between the quantization circuit 211 and a second output signal Von. In one embodiment, the quantization operation includes the quantization circuit 211 being configured to generate a quantized output signal QO1 based on a second input signal Vin and at least one quantization threshold level, and the amplification stage circuit 221 being configured to linearly amplify the quantized output signal QO1 to generate a second output signal Von.

[0042] Refer to Figures 12A and 13. Figure 13 shows waveform diagrams of the quantized output signals corresponding to Figures 12A and 12B according to two embodiments of the present invention. In the embodiment shown in Figure 12A, the quantized output signal QO1 is a step wave associated with the fundamental frequency Ff. The step wave includes three levels, corresponding to a first step level ST1, a second step level ST2, and a ground level GND, respectively.

[0043] Refer to Figures 12B and 12A. The second amplifier 2112B in Figure 12B is similar to the second amplifier 2112A in Figure 12A. The difference is that the quantized output signal QO2 generated by the quantization circuit 212 in Figure 12B is a square wave related to the fundamental frequency Ff. The square wave contains two levels corresponding to the first step level ST1 and the ground level GND. For further details of Figure 12B, refer to the description of Figure 12A.

[0044] Figure 14 shows a schematic circuit diagram of a second amplifier corresponding to the hybrid differential amplifier of Figure 12A, according to an embodiment of the present invention. The hybrid differential amplifier 2114 of Figure 14 is a specific embodiment of the hybrid differential amplifier 2112A of Figure 12A. In one embodiment, the quantization circuit 211 includes a quantization control circuit 230 and a selection circuit 240. In this embodiment, the quantization operation includes the selection circuit 240 generating a quantized output signal QO1, and the output signal QO1 being linearly amplified by the amplification stage circuit 221 to generate a second output signal Von. For further details of the operation of the quantization control circuit 230 and the selection circuit 240, please refer to the description of Figure 6.

[0045] As those skilled in the art will see, in other embodiments, the selection circuit 240 in Figure 14 can also be configured as the selection circuits 241 to 244 shown in Figures 8 to 11.

[0046] Figure 15A shows a schematic diagram of an amplification stage circuit corresponding to the second amplifier in Figure 12B, according to a particular embodiment of the present invention. In one particular embodiment, the amplification stage circuit 222 in Figure 12B may be configured as the amplification stage circuit shown in Figure 15A. As shown in Figure 15A, the amplification stage circuit 222 is configured as a Class B amplifier including a first high-side transistor QH1 and a first low-side transistor QL1. The gate of the first high-side transistor QH1 is coupled to the gate of the first low-side transistor QL1, and both are further coupled to a quantization circuit 212. The first high-side transistor QH1 and the first low-side transistor QL1 are connected in series between a supply voltage PVDD and ground to generate a second output signal Von. In one embodiment, the first high-side transistor QH1 is an NMOS transistor and the first low-side transistor QL1 is a PMOS transistor. In this embodiment, the quantized output signal QO2 has square wave characteristics and is linearly amplified by the amplification stage circuit 222 configured as a Class B amplifier. Due to the inherent crossover distortion of the Class B amplifier, a transient region occurs near the zero-crossing point of the output waveform. As a result, although the quantized output signal QO2 itself is a square wave, the second output signal Von generated by such linear amplification exhibits a step waveform with intermediate levels and therefore essentially has step wave characteristics. In one embodiment, the waveform of the second output signal Von in Figure 12B or Figure 15A corresponds to the first waveform in Figure 13, which is a step wave including a first step level ST1, a second step level ST2, and a ground level GND. In the embodiment of Figure 15A, the duration TC of the second step level ST2 is related to the turn-on thresholds of the first high-side transistor QH1 and the first low-side transistor QL1. In this embodiment, the supply voltage PVDD has the first step level ST1, and the ground potential corresponds to the ground level GND.

[0047] Figure 15B shows a schematic diagram of an amplification stage circuit corresponding to the second amplifier in Figures 12A and 12B, according to a particular embodiment of the present invention. In one particular embodiment, the amplification stage circuits 221 and 222 in Figures 12A and 12B can be configured as the amplification stage circuit shown in Figure 15B, respectively. As shown in Figure 15B, the amplification stage circuit 221 or 222 is configured as a Class AB amplifier including a second high-side transistor QH2, a second low-side transistor QL2, and a level shifter 50. In one embodiment, the second high-side transistor QH2 is an NMOS transistor, and the second low-side transistor QL2 is a PMOS transistor. In one embodiment, the first terminal N1 and the second terminal N2 of the level shifter 50 are coupled to the gates of the second high-side transistor QH2 and the second low-side transistor QL2, respectively, and the level shifter 50 is configured to maintain the voltage difference between them. An input terminal (for example, the second terminal N2 in this embodiment) is coupled to a quantized output signal QO1 or QO2 to control the voltages on the first terminal N1 and the second terminal N2. In one embodiment, a second high-side transistor QH2 and a second low-side transistor QL2 are connected in series to generate a second output signal Von. In one embodiment, the waveform of the second output signal Von in Figure 15B corresponds to the first waveform in Figure 13 (i.e., a step wave including a first step level ST1, a second step level ST2, and a ground level GND). In this embodiment, the duration TC of the second step level ST2 is related to the turn-on thresholds of the second high-side transistor QH2 and the second low-side transistor QL2 and the offset level of the level shifter 50. Specifically, when the offset level is smaller than the sum of the absolute values ​​of the turn-on thresholds of the second high-side transistor QH2 and the second low-side transistor QL2, the amplification stage circuit 221 or 222 exhibits characteristics similar to a Class B amplifier. By adjusting the offset level, the duration TC of the second step level ST2 can be adjusted. In this regard, the level shifter provides the flexibility to allow the Class AB amplifier to operate like a highly linear amplifier or a distortion-prone amplifier, depending on the selected offset level.In this embodiment, the supply voltage PVDD has a first step level ST1, and the ground potential corresponds to the ground level GND.

[0048] It should be noted that the quantized output signal QO1 generated by the quantization circuit 211 in Figure 12A is a step wave with at least three quantized output levels, and therefore the amplification stage circuit 221 must be a highly linear amplifier. This is because the amplifier needs to faithfully preserve all three different levels of the input signal without introducing transient distortion. For this reason, the amplification stage circuit 221 is suitable for configuration as a highly linear Class AB amplifier as shown in Figure 15B. In contrast, since the quantized output signal QO2 in Figure 12B is a square wave, the amplification stage circuit 222 can utilize its inherent distortion characteristics to generate a second output signal Von with step wave characteristics by linearly amplifying the quantized output signal QO2. Therefore, the amplification stage circuit 222 can be configured as a less linear Class B or Class AB amplifier as shown in Figure 15A or Figure 15B.

[0049] Figure 16 shows a circuit block diagram of a hybrid differential amplifier corresponding to Figure 2B according to an embodiment of the present invention. In one embodiment, as shown in the hybrid differential amplifier 16 of Figure 16, the first amplifier 1016 includes a pre-processing circuit 510, a PWM circuit 520, a logic / level shift circuit 530, and a switching power stage circuit 540. In one embodiment, the pre-processing circuit 510 generates a pre-processed output signal QOP based on a first input signal Vip and / or a second input signal Vin. The pre-processing operation will be described in detail later. The PWM circuit 520 generates a PWM output signal SPW based on a comparison of the pre-processed output signal QOP with a triangular wave VTR2. The switching power stage circuit 540 includes a high-side transistor M1 and a low-side transistor M2 for switching an inductor L based on the PWM output signal SPW to generate a first output signal Vop.

[0050] In one embodiment, as shown in Figure 16, the second amplifier 2016 includes a loop filter circuit 610, a gain stage circuit 620, and an amplification stage circuit 630. The loop filter circuit 610 linearly integrates the difference between the differential output signal Vod and the differential input signal Vid to generate a loop filter signal Vftr. The gain stage circuit 620 linearly amplifies the loop filter signal Vftr to generate a gain output signal Vgo. The amplification stage circuit 630 linearly amplifies the gain output signal Vgo to generate a second output signal Von. In this embodiment, the second amplifier 2016 performs feedback control so that the second output signal Von includes a step wave related to the fundamental frequency Ff (see previous description of step waves).

[0051] Figure 17 shows a circuit block diagram of a preprocessing circuit corresponding to the first amplifier in Figure 16, according to one embodiment of the present invention. In one embodiment, the preprocessing circuit 510 in Figure 16 is configured as the preprocessing circuit 511 shown in Figure 17. In one embodiment, the preprocessing circuit 511 includes an inverting amplifier 51, a quantization circuit 52, and an adder 53. In the embodiment of Figure 17, the preprocessing operation includes inverting the first input signal Vip with the inverting amplifier 51 to generate an inverted signal Vin' that is in phase with the second input signal Vin; performing the aforementioned quantization operation on the inverted signal Vin' with the quantization circuit 52 based on at least one quantization threshold level to generate a quantized output signal QOP'; and superimposing the quantized output signal QOP' with the first input signal Vip with the adder 53 to generate a preprocessed output signal QOP. In this embodiment, the quantized output signal QOP' includes a step wave having three levels (a first step level ST1, a second step level ST2, and a ground level GND). As those skilled in the art will see, it should be noted that the quantization circuit 52 can be configured as the quantization circuit 211 shown in Figure 14.

[0052] The present invention has been described in considerable detail with reference to certain preferred embodiments. It should be understood that this description is illustrative and not intended to limit the broadest scope of the invention. Embodiments or claims of the invention do not need to achieve all the objectives or advantages of the invention. The title and abstract are provided to aid in searching and are not intended to limit the scope of the invention. Those skilled in the art will readily recall variations and modifications within the spirit of the invention. For example, performing an action "according to" a particular signal as described in the context of the invention is not strictly limited to performing an action according to the signal itself, but can also be performed according to a transformed or augmented or reduced form of the signal. That is, the signal can be processed before the action is performed by voltage-to-current conversion, current-to-voltage conversion, and / or ratio conversion, etc. Each of the embodiments described herein is not limited to being used alone. In accordance with the spirit of the invention, two or more of the embodiments described herein can be used in combination. For example, two or more embodiments can be used together, or parts of one embodiment can be used to replace corresponding parts of another embodiment. In light of the foregoing, the spirit of the present invention encompasses all such and other modifications and variations, which should be interpreted as falling within the scope of the claims and their equivalents. [Explanation of Symbols]

[0053] 20A Hybrid Differential Amplifier 20B Hybrid Differential Amplifier 30A Hybrid Differential Amplifier 30B Hybrid Differential Amplifier 40 Multiplexer 42 buffers 50 Level Shifter 51 Inverting Amplifier 52 Quantization circuit 53 Adder 110 Digital-to-Analog Converter 120 Loop Filter Circuit 130 Superimposed Circuits 140 PWM circuit 150 Logic / Level Shift Circuits 160 Switching power stage circuits 210 Quantization circuit 210A quantization circuit 210B Quantization circuit 211 Quantization circuit 212 Quantization circuit 220 Amplifier Stage Circuit 221 Amplifier Stage Circuit 222 Amplifier Stage Circuit 230 Quantization control circuit 240 Selection Circuit 241-244 Selection Circuit 250 Analog-to-Digital Converter 510 Pre-processing circuit 511 Pre-processing circuit 520 PWM circuit 530 Logic / Level Shift Circuit 540 Switching power stage circuits 610 Loop Filter Circuit 620 Gain Stage Circuit 630 Amplifier Stage Circuit 1000 First Amplifier 1016 First Amplifier 1100 First Amplifier 1105 First Amplifier 2000 Second Amplifier 2016 Second Amplifier 2100 Second amplifier 2100A Second Amplifier 2100B Second Amplifier 2112A Second Amplifier 2112B Second Amplifier 2114 Hybrid Differential Amplifier 2200 Second amplifier 2206 Second Amplifier 2208~2211 Second Amplifier Din Digital Input Signal Dout Digital Output Signal Ff Fundamental frequency f_Von related signal GND (Ground Level) L Inductor LML lower limit of supply voltage Upper limit of LMU supply voltage LXp switching node signal M1 High-Side Transistor M2 Low-Side Transistor PVDD supply voltage PVDD1 supply voltage PVDD1' divided voltage QH1 First high-side transistor QH2 Second high-side transistor QL1 First low-side transistor QL2 Second Low-Side Transistor QO1 Quantized output signal QO2 Quantized output signal QON output signal QOP output signal QOP' Quantized output signal QS quantization control signal SPW PWM output signal ST1 First Stair Level ST2 Second Stair Level SW1~SW3 Switches SW11~SW1n Switches TC duration Td delay time Tf time Vftr loop filter signal Vftr' Loop filter signal Vgo gain output signal Vid differential input signal Vin is the second input signal. Vin' Inverted signal Vip First Input Signal VOD differential output signal Von, the second output signal Von' Second output signal Vop First output signal VTR1 triangle wave VTR2 triangle wave

Claims

1. A hybrid differential amplifier configured to generate a differential output signal based on a differential input signal to drive a load, wherein the differential input signal has a fundamental frequency, and the hybrid differential amplifier, A first amplifier configured as an inductive switching converter, the first amplifier configured to generate a first output signal of the differential output signal by performing pulse width modulation (PWM) conversion based on a first input signal of the differential input signal and switching an inductor, A second amplifier configured to generate a second output signal of the differential output signal based on a second input signal of the differential input signal, It has, The second amplifier is configured as a different type of amplifier than the inductive switching converter, Either the first amplifier or the second amplifier is further configured to generate the first output signal or the second output signal based on feedback from the differential output signal such that the differential output signal is linearly related to the differential input signal. The other of the first or second amplifier is further configured to perform a quantization operation on the first or second input signal such that the second output signal includes a step wave related to the fundamental frequency, the step wave including at least three quantized output levels. A hybrid differential amplifier characterized in that the quantization processing operation includes generating a quantized output signal based on the first input signal or the second input signal and at least one quantization threshold level such that the second output signal includes the step wave.

2. The at least three quantized output levels include a first step level, a second step level, and a ground level. The hybrid differential amplifier according to claim 1, wherein the second step level is lower than the first step level and higher than the ground level, and the duration of the second step level is longer than the delay time between the first output signal and the second output signal such that the distortion level of the differential output signal is below a predetermined level.

3. The hybrid differential amplifier according to claim 2, wherein the first step level corresponds to the voltage level of the supply voltage, and the second step level corresponds to the voltage divider level of the supply voltage.

4. The second amplifier described above is A quantization control circuit coupled to the second input signal, A selection circuit coupled between the quantization control circuit and the second output signal, Includes, The aforementioned quantization processing operation is, The quantization control circuit is configured to generate a quantization control signal based on the second input signal and the at least one quantization threshold level, The selection circuit is configured to select the first step level, the second step level, or the ground level based on the quantization control signal, and to generate the quantized output signal, The hybrid differential amplifier according to claim 2, wherein the quantized output signal corresponds to the second output signal.

5. The first amplifier is, A loop filter circuit is configured to generate a loop filter signal by performing a linear integral based on the difference between the differential output signal and the differential input signal, A PWM circuit configured to generate a PWM output signal based on a comparison between the loop filter signal and a triangular wave, A switching power stage circuit configured to generate the first output signal by switching the inductor based on the PWM output signal, Includes, The hybrid differential amplifier according to claim 4, wherein the first amplifier is configured to perform feedback control such that the first output signal includes a superposition of the first input signal and the step wave.

6. The second amplifier is configured as a linear amplifier operating in the continuous-time domain, A quantization circuit coupled to the second input signal, An amplification stage circuit coupled between the quantization circuit and the second output signal, Includes, The aforementioned quantization processing operation is, The quantization circuit is configured to generate the quantized output signal based on the second input signal and the at least one quantization threshold level, wherein the quantized output signal includes a square wave or a step wave associated with the respective fundamental frequencies. The amplification stage circuit is configured to linearly amplify the quantized output signal to generate the second output signal, The hybrid differential amplifier according to claim 2, wherein the square wave includes two levels corresponding to the first step level and the ground level, and the step wave includes three levels corresponding to the first step level, the second step level, and the ground level.

7. The first amplifier is, A loop filter circuit is configured to generate a loop filter signal by performing a linear integral based on the difference between the differential output signal and the differential input signal, A PWM circuit configured to generate a PWM output signal based on a comparison between the loop filter signal and a triangular wave, A switching power stage circuit configured to generate the first output signal by switching the inductor based on the PWM output signal, Includes, The hybrid differential amplifier according to claim 6, wherein the first amplifier performs feedback control such that the first output signal includes a superposition of the first input signal and the step wave.

8. If the quantized output signal includes the square wave related to the fundamental frequency, the amplification stage circuit, A Class B amplifier comprising a first high-side transistor and a first low-side transistor, wherein the gates of the first high-side transistor and the gates of the first low-side transistor are coupled to each other and coupled to the quantized output signal, the first high-side transistor and the first low-side transistor are connected in series between a supply voltage and ground potential to generate the second output signal, and the duration of the second step level is related to the turn-on threshold of the first high-side transistor and the turn-on threshold of the first low-side transistor, or A Class AB amplifier comprising a second high-side transistor, a second low-side transistor, and a level shifter, wherein the first and second terminals of the level shifter are coupled to the gates of the second high-side transistor and the second low-side transistor, respectively, to maintain the voltage difference between the gates of the second high-side transistor and the second low-side transistor, the input terminal of the level shifter is coupled to the quantized output signal to control the voltages of the first and second terminals, the second high-side transistor and the second low-side transistor are connected in series between a supply voltage and ground potential to generate the second output signal, and the duration of the second step level is related to the turn-on threshold of the second high-side transistor, the turn-on threshold of the second low-side transistor, and the offset level of the level shifter. Includes, The hybrid differential amplifier according to claim 6, wherein the supply voltage has the first step level, the ground potential corresponds to the ground level, and the offset level is positively correlated with the voltage difference.

9. If the quantized output signal includes the step wave related to the fundamental frequency, the amplification stage circuit, A Class AB amplifier comprising a high-side transistor, a low-side transistor, and a level shifter, wherein the first and second terminals of the level shifter are coupled to the gates of the high-side transistor and the low-side transistor, respectively, to maintain the voltage difference between the gates of the high-side transistor and the low-side transistor, the input terminal of the level shifter is coupled to the quantized output signal to control the voltages of the first and second terminals, the high-side transistor and the low-side transistor are connected in series between a supply voltage and ground potential to generate the second output signal, and the duration of the second step level is related to the turn-on threshold of the high-side transistor, the turn-on threshold of the low-side transistor, and the offset level of the level shifter. The hybrid differential amplifier according to claim 6, wherein the supply voltage has the first step level, the ground potential corresponds to the ground level, and the offset level is positively correlated with the voltage difference.

10. The first amplifier is, A preprocessing circuit is configured to perform a preprocessing operation based on the first input signal or the second input signal to generate a preprocessed output signal, A PWM circuit configured to generate a PWM output signal based on a comparison of the pre-processed output signal and a triangular wave, A switching power stage circuit configured to generate the first output signal by switching the inductor based on the PWM output signal, Includes, The preprocessing operation includes: performing the quantization operation based on the first input signal or the second input signal and the at least one quantization threshold level to generate the quantized output signal; and superimposing the quantized output signal with the first input signal to generate the preprocessed output signal. The hybrid differential amplifier according to claim 2, wherein the quantized output signal includes the step wave, the step wave includes the first step level, the second step level, and the ground level.

11. The second amplifier described above is A loop filter circuit is configured to generate a loop filter signal by performing a linear integral based on the difference between the differential output signal and the differential input signal, A gain stage circuit configured to linearly amplify the aforementioned loop filter signal to generate a gain output signal, An amplification stage circuit configured to linearly amplify the gain output signal to generate a second output signal, Includes, The hybrid differential amplifier according to claim 10, wherein the second amplifier performs feedback control so that the second output signal includes the step wave.

12. A hybrid differential amplifier method configured to generate a differential output signal based on a differential input signal to drive a load, wherein the differential input signal has a fundamental frequency, and the hybrid differential amplifier method The steps include: generating a first output signal of the differential output signal by performing PWM (pulse width modulation) conversion based on the first input signal of the differential input signal; The steps include generating a second output signal of the differential output signal based on a second input signal of the differential input signal, Includes, The second output signal is generated by a method different from the PWM conversion, Either the first output signal or the second output signal is further generated based on feedback from the differential output signal such that the differential output signal is linearly related to the differential input signal. The other of the first output signal or the second output signal is further generated based on a quantization operation of the first input signal or the second input signal such that the second output signal includes a step wave related to the fundamental frequency, the step wave includes at least three quantized output levels, A hybrid differential amplifier method characterized in that the quantization processing operation includes generating a quantized output signal based on the first input signal or the second input signal and at least one quantization threshold level such that the second output signal includes the step wave.

13. The at least three quantized output levels include a first step level, a second step level, and a ground level. The hybrid differential amplification method according to claim 12, wherein the second step level is lower than the first step level and higher than the ground level, and the duration of the second step level is longer than the delay time between the first output signal and the second output signal such that the distortion level of the differential output signal is below a predetermined level.

14. The hybrid differential amplifier method according to claim 13, wherein the first step level corresponds to the voltage level of the supply voltage, and the second step level corresponds to the voltage divider level of the supply voltage.

15. The aforementioned quantization processing operation is, A quantization control signal is generated based on the second input signal and the at least one quantization threshold level. Based on the quantization control signal, the first step level, the second step level, or the ground level is selected, and the quantized output signal is generated. Includes, The hybrid differential amplification method according to claim 13, wherein the quantized output signal corresponds to the second output signal.

16. The step of generating the first output signal is: A loop filter signal is generated by performing a linear integral based on the difference between the differential output signal and the differential input signal. The PWM output signal is generated based on a comparison between the aforementioned loop filter signal and a triangular wave. The first output signal is generated by switching based on the PWM output signal, Includes, The hybrid differential amplifier method according to claim 15, wherein the step of generating the first output signal includes performing feedback control such that the first output signal includes a superposition of the first input signal and the step wave.

17. The aforementioned quantization processing operation is, A quantized output signal is generated based on the second input signal and the at least one quantization threshold level, wherein the quantized output signal includes a square wave or a step wave associated with the fundamental frequency, The quantized output signal is linearly amplified to generate a second output signal, Includes, The hybrid differential amplifier method according to claim 13, wherein the square wave includes two levels corresponding to the first step level and the ground level, and the step wave includes three levels corresponding to the first step level, the second step level, and the ground level.

18. The step of generating the first output signal is: A loop filter signal is generated by performing a linear integral based on the difference between the differential output signal and the differential input signal. The PWM output signal is generated based on a comparison between the aforementioned loop filter signal and a triangular wave. The first output signal is generated by switching based on the PWM output signal, Includes, The hybrid differential amplifier method according to claim 17, wherein the step of generating the first output signal includes performing feedback control such that the first output signal includes a superposition of the first input signal and the step wave.

19. If the quantized output signal includes the square wave related to the fundamental frequency, the step of linearly amplifying the quantized output signal is: The method involves performing Class B amplification to control the conduction level between a first high-side transistor and a first low-side transistor, thereby generating the second output signal, wherein the first high-side transistor and the first low-side transistor are connected in series between the supply voltage and the ground potential to generate the second output signal, and the duration of the second step level is related to the turn-on threshold of the first high-side transistor and the turn-on threshold of the first low-side transistor. or Performing Class AB amplification, maintaining the voltage difference between the gate of a second high-side transistor and the gate of a second low-side transistor, and controlling the voltage difference based on the quantized output signal to generate the second output signal, wherein the second high-side transistor and the second low-side transistor are connected in series between the supply voltage and ground potential to generate the second output signal, and the duration of the second step level is related to the turn-on threshold of the second high-side transistor, the turn-on threshold of the second low-side transistor, and the offset level, wherein the offset level is positively correlated with the voltage difference. Includes, The hybrid differential amplifier method according to claim 17, wherein the supply voltage has the first step level and the ground potential corresponds to the ground level.

20. If the quantized output signal includes the step wave related to the fundamental frequency, the step of linearly amplifying the quantized output signal is: Performing Class AB amplification to maintain a voltage difference between the gates of a high-side transistor and a low-side transistor, and controlling the voltage difference based on the quantized output signal to generate the second output signal, wherein the high-side transistor and the low-side transistor are connected in series between a supply voltage and ground potential to generate the second output signal, and the duration of the second step level is related to the turn-on threshold of the high-side transistor, the turn-on threshold of the low-side transistor, and an offset level, the offset level being positively correlated with the voltage difference. The hybrid differential amplifier method according to claim 17, wherein the supply voltage has the first step level and the ground potential corresponds to the ground level.

21. The step of generating the first output signal is: The process involves performing a preprocessing operation based on the first input signal or the second input signal to generate a preprocessed output signal, A PWM output signal is generated based on a comparison between the pre-processed output signal and a triangular wave. The first output signal is generated by switching based on the PWM output signal, Includes, The aforementioned preprocessing operation is: The quantization processing operation is performed based on the first input signal or the second input signal and the at least one quantization threshold level to generate the quantized output signal, The process includes superimposing the quantized output signal with the first input signal to generate the pre-processed output signal, The hybrid differential amplification method according to claim 13, wherein the quantized output signal includes the step wave, the step wave includes the first step level, the second step level, and the ground level.

22. The step of generating the second output signal is: A loop filter signal is generated by performing a linear integral based on the difference between the differential output signal and the differential input signal. The loop filter signal is linearly amplified to generate a gain output signal, The above-mentioned gain output signal is linearly amplified to generate a second output signal, Includes, The hybrid differential amplifier method according to claim 21, wherein the step of generating the second output signal includes performing feedback control such that the second output signal includes the step wave.

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