Integrated PCM driver

Abstract

Methods and apparatus for controlling a PCM switch are disclosed. The described apparatus includes a PCM switch driver and logic and control circuitry, all of which are integrated on the same chip with the PCM and the associated heater. Various architectures related to the driver are also presented, including architectures that implement feedback mechanisms to mitigate variations from process, temperature, and supply voltage.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. patent application No. 17 / 815,193, filed on July 26, 2022, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] The present disclosure relates to phase change material (PCM) switches, and more particularly, to methods and apparatus for integrating a PCM switch and its driver onto the same chip. Background Art

[0004] Phase change materials are commonly used in the manufacture of integrated circuit (IC) switches because they can be thermally transformed between an amorphous state and a crystalline state, exhibiting a change in resistivity of several orders of magnitude. FIG. 1A shows a block diagram of a prior art PCM switch (100A) consisting of a volume of phase change material (PCM) (102) and an adjacent heater (101) (such as a resistor). The heater (101) generates the thermal energy required to transform the phase change material from one of the amorphous or crystalline states to the other.

[0005] An alternative arrangement for transforming phase change materials is to inject current directly through the material. However, such an arrangement has proven to be problematic for RF applications.

[0006] Currently, in most applications, PCM switches are programmed and driven using laboratory equipment. This is a rather bulky solution that often results in lower performance and higher cost than expected. A more compact and higher performance solution, such as a monolithic commercial switch product using PCM switches, is highly desirable. In such a product, the PCM, driver, and associated logic circuitry would be integrated on the same chip. The present invention addresses this need. Summary of the invention

[0007] The disclosed method and apparatus implement an integrated driver to program (i.e., turn on / off) a phase change material (PCM) switch. The integrated driver interfaces the input of an application circuit to the PCM switch. The described apparatus provides the required programming waveform to the PCM switch to cause the switch to transition between an on state and an off state.

[0008] According to a first aspect of the present disclosure, there is provided a phase change material (PCM) driving device for programming the state of a PCM switch, comprising: a PCM switch including a heater and a volume of phase change material coupled to the heater; a driver circuit connected to the heater and configured to provide a first electrical pulse curve or a second electrical pulse curve to the heater according to a desired state to which the PCM switch is to be programmed; and a logic and control circuit coupled to the driver and configured to program the PCM switch by: providing a first control pulse to the driver when the PCM switch is to be programmed to an on state corresponding to the first electrical pulse curve, and providing a second control pulse to the driver when the PCM switch is to be programmed to an off state corresponding to the second electrical pulse curve, wherein the PCM switch, the driver, and the logic and control circuit are integrated on the same chip.

[0009] According to a second aspect of the present disclosure, a method for programming the state of a phase change material (PCM) switch is disclosed, the PCM switch comprising a heater and a certain volume of PCM, the method comprising: providing a driver circuit; integrating the driver and the PCM switch on the same chip; applying a first control pulse to the driver circuit when the PCM switch is to be programmed to an on state; and applying a second control pulse to the driver when the PCM switch is to be programmed to an off state.

[0010] According to a third aspect of the present disclosure, a method for programming a state of a phase change material (PCM) switch stack is disclosed, the PCM switch stack comprising a plurality of PCM switches arranged in a stacked configuration, the method comprising driving the plurality of PCM switches in separate time intervals, driving one or more PCM switches at a time.

[0011] Other aspects of the disclosure are provided in the description, drawings and claims of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1A shows a block diagram of a prior art PCM switch.

[0013] Figure 1B The power curve for driving the PCM switching heater is shown.

[0014] Figure 2 An exemplary driving device for a PCM switch according to an embodiment of the present disclosure is shown.

[0015] Figure 3A An exemplary PCM switch driver is shown when the driver is in an off state according to an embodiment of the present disclosure.

[0016] Figure 3BAn exemplary PCM switch driver is shown when the driver is in an on state according to an embodiment of the present disclosure.

[0017] Figure 4 An exemplary timing diagram according to an embodiment of the present disclosure is shown.

[0018] Figure 5 An exemplary state diagram is shown according to an implementation of the present disclosure.

[0019] Fig. 6A An exemplary timing diagram of staggered control pulses according to an embodiment of the present disclosure is shown.

[0020] Figure 6B An exemplary drive arrangement of a PCM switch stack according to an embodiment of the present disclosure is shown.

[0021] Figure 7 An exemplary PCM switch driver according to an embodiment of the present disclosure is shown.

[0022] Fig. 8A An exemplary PCM switch driver according to an embodiment of the present disclosure is shown.

[0023] Figure 8B An exemplary PCM switch driver according to an embodiment of the present disclosure is shown.

[0024] Like reference numbers and designations in the various drawings indicate like elements. DETAILED DESCRIPTION

[0025] Figure 1B Two different electrical pulse profiles for switching the resistivity state of the PCM (102) of FIG. 1A according to the present disclosure are shown. Such electrical pulse profiles are applied to the heater (101) of FIG. 1A to produce different thermal profiles, which result in amorphizing the PCM (102) of FIG. 1A to a high resistance state (off or open) using a higher power, short period pulse (110), or crystallizing the PCM (102) to a low resistance state (on or closed) using a lower power, long period pulse (120). The pulses (110, 120) may typically have pulse widths of 100 nsec and 1 usec, respectively.

[0026] Figure 2An exemplary driving device for a PCM switch (200) according to an embodiment of the present disclosure is shown. The driving device includes a volume of PCM (202), a heater (201), a first driver (230), a second driver (230'), a logic and timing circuit (220), a serial interface (240), and a power module (210). For the purpose of the present disclosure, element (201) and element (202) will be collectively defined as a PCM switch. As mentioned above, different power curves are implemented to drive the PCM switch. A pulse with higher power and shorter pulse width is implemented to put the PCM switch in an off state, while a different pulse with lower power and longer pulse width is implemented to put the PCM switch in an on state. The driver (230, 230') is used to drive the heater (201) to switch the PCM switch (201, 202) to an off state / on state, respectively. Therefore, a higher bias voltage (VH) is provided by the power module (210) to the driver (230), while a lower bias voltage (VL) is provided by the power module (210) to the driver (230'). In an embodiment, a single driver instead of two drivers may be implemented to generate pulse waveforms for both the on-state and the off-state of the PCM switches (201, 202). According to the teachings of the present disclosure, the width of the pulse at the output of the driver (230, 230') for driving the heater (201) may be programmable. In an embodiment, all components of the driving device (200) are integrated on the same chip, as shown by the exemplary dashed box (250).

[0027] Further references Figure 2 The logic and timing circuit (220) provides a logic level pulse corresponding to the state of the PCM switch (201, 202). The logic and timing circuit (220) receives a digital reference clock input (REF_CLK) and a digital control input (SW_IN), which are used to control the on or off state of the PCM switch (201, 202). In other words, based on the state of the control input (SW_IN) and using the digital reference clock input (REF_CLK), a power curve with appropriate amplitude and width is generated corresponding to the desired state of the PCM (202) and fed to the heater (201). As a result, the PCM switch (021, 202) transitions between the on state and the off state based on the digital control input (SW_IN).

[0028] Continue to refer to Figure 2, the power module (210) also provides a bias voltage (VDD) for the logic and timing circuit (220). The switch arrangement (200) also includes a serial interface (240) connected to the logic and timing circuit (220). The serial interface (240) includes an input (S_IN) and can be implemented using a serial peripheral interface (SPI) standard, a mobile industry processor interface (MIPI) standard, etc. The input control signal can also come from the serial interface.

[0029] Figure 3A A representation showing an embodiment according to the present disclosure is shown Figure 2 An exemplary PCM switch driver (300A) is an implementation of any of the drivers (230, 230') of FIG. 1 . The driver (300A) includes a first driver switch stack (303) including transistors (T3, T5), and a second driver switch stack (304) including transistors (T4, T6). The driver switch stacks (303, 304) are each arranged in series with a corresponding load device transistor (T1, T2), respectively. An output transistor (T7) is also shown, which delivers a downstream heater (e.g., Figure 2 The driver (300A) further comprises a series arrangement of logic inverters (301, 302) receiving a control input (SW_IN). The logic inverters (301, 302) operate at a bias voltage (VDD) and drive transistors (T5, T6) respectively. Figure 2 As described in the embodiments of the present disclosure, a bias voltage (VH) is also provided to the driver. According to the teachings of the present disclosure, the stacked arrangement shown in the figure allows for improved voltage handling. If necessary, transistor stacks can be increased or decreased depending on the transistor voltage handling capabilities and the required output drive.

[0030] Figure 3A The voltage values ​​shown in represent the case where the PCM switch driver (300A) is in the off state. No current is sent to the heater. Exemplary values ​​of the bias voltages (VDD, VH) may be 2.5V, 5V, respectively. Based on such exemplary bias values, the voltage levels at various points of the driver (300A) are shown. On the other hand, Figure 3B Shown with Figure 3A The same driver as in , but this time with a voltage value that puts the PCM switch driver in the on state. As before, this is used to transition the PCM material to either the on state or the off state depending on the output amplitude and timing.

[0031] Reference FIG. 3A to FIG. 3B, the transistors (T3, T4, T5, T6) may be NFETs, and the transistors (T1, T2, T7) may be PFETs. Based on the exemplary bias voltages of (2.5V, 5V) for the bias voltages (VDD, VH), the NFETs and PFETs may each be designed to handle a voltage of at least (2.5V, 5V), respectively.

[0032] Figure 4 Representation and Figure 2 An exemplary timing diagram related to an embodiment of the present invention. Signals (410, 420, 430) represent the relationship between control input and time, heater current and time, and heater voltage and time, respectively. Pulses (401, 402, 403) correspond to the case where the PCM switch is driven or programmed to the off state, while pulses (401', 402', 403') represent the case where such a switch is driven or programmed to the on state.

[0033] Reference Figure 2 , the operation of the logic and timing module (220) can be described as a state machine. Figure 5 An exemplary state diagram (500) according to an embodiment of the present disclosure is shown. Figure 2 and Figure 5 Both, Figure 2 The PCM switches (201, 202) can be programmed (501) to be in the on or off state based on the state (503) of the digital control input (SW_IN). When the PCM switches (201, 202) are turned to the on state, the first counter (502) will generate a turn-on pulse with a desired width to the driver (230) of FIG. 1, see also Figure 3A The desired width can be achieved by counting the number of cycles in the reference clock (clk) as input to the first counter (502). Similarly, when the PCM switch (201, 202) is turned to the off state, the second counter (502') will generate an off pulse with the desired width to the driver (230') of Figure 1, see also Figure 3B In this case, the width of the off pulse may also be realized by counting the number of clock cycles in the reference clock (clk) as the input of the second counter (502'). The control input of the first counter and the control input of the second counter may have different values.

[0034] As mentioned previously, a pulse needs to be applied to the heater to transition the PCM switch between one state and another. More specifically, when transitioning to the off state, a higher power curve needs to be achieved. This can be problematic when designing PCM switches arranged in a stacked configuration to improve voltage handling. In such a stack, each PCM requires programming of its own individual heater, and changing the state of all stacked PCMs simultaneously can tax the power supply. This presents power supply design challenges for applications using stacks of PCM switches.

[0035] According to the teachings of the present disclosure, changing the state of the PCM switches within the stack can be performed in a staggered manner so that not all PCM switches change state at the same time. As an example, this can be performed one PCM device at a time, or several PCM devices at a time. As a result, the peak current drawn from the power supply can be reduced. To further illustrate this teaching, refer to Fig. 6A , which shows a timing diagram presenting the relationship between control input pulses and time when staggered control of a PCM switch stack is adopted. Control pulses (601, 601') are issued sequentially, and they correspond to programming the off state of two PCM switches in the stack. Similarly, control pulses (602, 602') are issued sequentially, and they correspond to programming the on state of two PCM devices in the stack. Fig. 6A The timing diagram is an example showing interleaved control, and it should be understood that such a concept can be extended to sequentially control all PCM switches within the stack, one or more at a time, until all PCM switches within the stack have changed state according to the control input.

[0036] The above teachings can be extended to an RF switch having multiple inputs and PCM devices and having at least two switch arms to turn off or on. In this embodiment, the control signals can be interleaved so that only one PCM device is programmed at a given time. If the switch arms include stacked PCM devices, each switch stack can be programmed at a given time interval, with each PCM switch of the stack being programmed at a given time.

[0037] As an example, Figure 6B An exemplary drive arrangement of a PCM switch stack (600B) is shown, which is similar to Fig. 6AAn exemplary implementation of the teachings disclosed above is related to an embodiment of the present invention. The driving device includes a PCM switch stack (650), a driver (D1, ..., Dn), a control and logic circuit (620), a power supply (610), and a serial interface (640). The PCM switch stack (600B) includes a plurality of PCM switches (PS1, ..., PSn) arranged in a stack configuration, wherein each PCM switch includes a heater and a certain volume of PCM. The logic and timing circuit (620) is based on the PCM switch stack (650B). Fig. 6A The teachings disclosed in the implementation method of the present invention are that a control input is provided to each of the drivers (D1, ..., Dn) in an interlaced manner. As a result, each of the drivers (D1, ..., Dn) provides a drive pulse to the corresponding PCM switch (PS1, ..., PSn) corresponding to the state of each power switch (PS1, ..., PSn). The power supply (610) provides a high bias voltage and a low bias voltage (VH, VL) to each driver (D1, ..., Dn). The bias voltages (VH, VL) correspond to the on / off states of the PCM switches within the PCM switch stack (6500), respectively. Refer to FIG. 6A to FIG. 6B Both, the states of the PCM switches (PS1, ..., PSn) can be changed one or more PCM switches at a time, and in separate / staggered time intervals. This means that less instantaneous current is drawn from the power supply to transition the switch stack (650) from one state to another, resulting in a simpler power supply design.

[0038] Figure 7 An exemplary PCM switch driver (700) is shown including a first driver stage (710) and a second driver stage (750), wherein the first driver stage (710) represents an embodiment of the present disclosure. Figure 2 The terminal (output) provides an input signal to a PCM (not shown). Figure 7 The implementation is similar to Figure 3A , wherein the teachings of the present disclosure are extended to handle larger supply voltages and output voltages. In the case of larger heater resistance values ​​or in the case of the same driver driving a heater stack, Figure 7The embodiment may be beneficial. The first driver stage (710) includes a first driver switch stack (701) including transistors (T1, ..., T4) and a second driver switch stack (701') including transistors (T1', ..., T4'). The driver switch stacks (701, 701') are each arranged in series with a corresponding transistor (T5, T5'). The first driver stage (710) also includes a quasi-latch (703) including transistors (T6, T6'). In particular, transistors T6 and transistors T6' are arranged to have positive feedback so that the resulting output signal quickly transitions from one state to another (i.e., the driver is turned off to turned on), and the output voltage swing has the amplitude required to drive the next stage.

[0039] Also shown are resistor ladders (702, 702') that provide bias to the gate terminals of transistors within the driver switch stacks (701, 701'), respectively. A control input (SW_IN) is applied directly to transistor (T1), while an inverted version of the control input (SW_IN) is applied to transistor (T1') via an inverter (704).

[0040] Further references Figure 7 According to an embodiment of the present disclosure, the transistors (T1, ..., T4, T1', ..., T4') may be NFETs and the transistors (T5, T5', T6, T6') may be PFETs. As an example, such an embodiment may be implemented using a bias voltage (VH) of 10V, in which case the NFETs will have a breakdown voltage handling of 2.5V or better and the PFETs will have a breakdown voltage handling of 5V or better. The output of the circuit is at the drain of the transistors (T5, T5') in order to drive a similar Figure 3A The transistor stack of the transistor (T7) shown in FIG.

[0041] Fig. 8AAn exemplary PCM switch arrangement (800A) according to an embodiment of the present disclosure is shown, wherein a feedback mechanism is provided upstream of a PCM driver. Specifically, the PCM switch arrangement (800A) includes a PCM driver (801), a PCM (802), a feedback circuit (805), and transistors (T2, T2') arranged as a current mirror (804). The feedback circuit (805) includes an operational amplifier (OP-amp) (803), a reference resistor (Rref), a reference voltage (Vref), and a transistor (T1). Rref is intended to be the same as the heater resistor to be controlled. Since the voltages at the two input terminals of the OP-amp (803) remain the same at the desired reference voltage (Vref), such a feedback circuit generates a desired current (Iref) through the reference resistor (Rref). The current mirror (804) essentially mirrors the current (Iref) and feeds this current to the PCM driver (801) to ensure that the desired voltage and current are generated in the heater corresponding to the desired state that the PCM (802) should be programmed to. By implementing this feedback mechanism, variations from process, temperature and supply voltage can be mitigated.

[0042] , Fig. 8A The implementation of the feedback mechanism will mean that the drive (801) is relatively Figure 3A , Figure 3B and Figure 7 Some design changes to the architecture shown in . Figure 8B An exemplary PCM driver (800B) according to an embodiment of the present disclosure is shown. The PCM driver (800B) represents Fig. 8A An exemplary implementation of a PCM driver (801) of the present invention includes a switch stack (813, 813') driven by circuits (810, 810'), each of which is provided to Fig. 8A When the PCM switch (802) is to be programmed to the on state, the output of the circuit (810) is high and the current Ion flows in the switch stack (813), as indicated by the arrow (820); and when the PCM switch (802) is to be programmed to the off state, the output of the circuit (810') is high and the current Ioff flows in the switch stack (813'), as indicated by the arrow (820').

[0043] Figure 8B It also shows that according to Fig. 8A The teaching of the additional input current Iref. Such current is fed to the switch stack (813) and the switch stack (813') through the current mirror (M5, M3) to generate the current Ion and through the current mirror (M5, M2) to generate the current Ioff.

[0044] The reference current (Iref) is fixed by the feedback circuit. The values ​​of currents Ion and Ioff are generated by the current mirror ratio, which is generated by the ratio of M3 and M2 relative to M5.

[0045] The PCM driver (800B) further includes a current mirror (812) for generating a current required by the heater through a terminal (OUT) corresponding to the on state and the off state of the PCM switch.

[0046] The term "MOSFET" as used in this disclosure includes any field effect transistor (FET) with an insulated gate - the gate voltage determines the conductivity of the transistor, and includes an insulated gate having a metal or metalloid, insulator and / or semiconductor structure. The term "metal" or "metalloid" includes at least one conductive material (such as aluminum, copper or other metal, or highly doped polysilicon, graphene or other electrical conductors), "insulator" includes at least one insulating material (such as silicon oxide or other dielectric materials), and "semiconductor" includes at least one semiconductor material.

[0047] As used in this disclosure, the term "radio frequency" (RF) refers to oscillation rates in the range of about 3 kHz to about 300 GHz. The term also includes frequencies used in wireless communication systems. RF frequencies can be the frequency of electromagnetic waves, or the frequency of alternating voltage or current in an electrical circuit.

[0048] With respect to the drawings cited in this disclosure, the sizes of the various elements are not to scale; some dimensions have been significantly exaggerated in the vertical and / or horizontal directions for clarity or emphasis. In addition, references to orientations and directions (e.g., "top," "bottom," "above," "below," "lateral," "vertical," "horizontal," etc.) are relative to the example drawings and are not necessarily absolute orientations or directions.

[0049] Various embodiments of the present invention can be implemented to meet various specifications. Unless otherwise specified above, selecting appropriate component values ​​is a matter of design choice. Various embodiments of the present invention can be implemented in any suitable integrated circuit (IC) technology (including but not limited to MOSFET structure) or in hybrid or discrete circuit form. Any suitable substrate and process (including but not limited to standard bulk silicon, high resistivity bulk CMOS, silicon on insulator (SOI) and silicon on sapphire (SOS)) can be used to manufacture integrated circuit embodiments. Unless otherwise specified above, embodiments of the present invention can be implemented in other transistor technologies, such as bipolar transistors, BiCMOS, LDMOS, BCD, GaAs HBT, GaN HEMT, GaAspHEMT and MESFET technology. However, when using SOI or SOS-based process manufacturing, or when using a process manufacturing with similar characteristics, embodiments of the present invention are particularly useful. The manufacture of SOI or SOS processes in CMOS enables circuits to have low power consumption, the ability to withstand high power signals during operation due to FET stacking, good linearity, and high frequency operation (i.e., up to and exceeding 300GHz radio frequency). Monolithic IC implementations are particularly useful because, through careful design, parasitic capacitances can generally be kept low (or at least consistent across all units, allowing them to be compensated for).

[0050] Depending on the particular specification and / or implementation technology (e.g., NMOS, PMOS, or CMOS, and enhancement mode or depletion mode transistor devices), voltage levels may be adjusted, and / or voltage and / or logic signal polarity may be reversed. Component voltage, current, and power handling capabilities may be adjusted as needed, such as by adjusting device size, "stacking" components (particularly FETs) in series to withstand higher voltages, and / or using multiple components in parallel to handle higher currents. Additional circuit components may be added to enhance the capabilities of the disclosed circuits and / or to provide additional functionality without significantly changing the functionality of the disclosed circuits.

[0051] Circuits and devices according to the present invention can be used alone or in combination with other components, circuits and devices. Embodiments of the present invention can be manufactured as integrated circuits (ICs), which can be packaged in IC packages and / or modules for ease of processing, manufacturing and / or improved performance. Specifically, IC embodiments of the present invention are often used in modules, in which one or more such ICs are combined with other circuit blocks (e.g., filters, amplifiers, passive components, and possible additional ICs) into a package. Then typically, ICs and / or modules are typically combined with other components on a printed circuit board to form a part of a final product (e.g., a cellular phone, a laptop computer, or an electronic tablet), or to form a more advanced module that can be used in a variety of products (e.g., vehicles, test equipment, medical devices, etc.). Through various configurations of modules and components, such ICs typically implement communication modes, typically wireless communication modes.

[0052] A number of embodiments of the present invention have been described. It should be appreciated that various modifications may be made without departing from the spirit and scope of the present invention. For example, some of the steps described above may be order-independent and thus may be performed in an order different from that described. Furthermore, some of the steps described above may be optional. The various activities described with respect to the methods identified above may be performed in a repetitive, serial, and / or parallel manner.

[0053] It should be understood that the above description is intended to illustrate, but not to limit, the scope of the invention, which is defined by the scope of the appended claims, and other embodiments are within the scope of the claims. In particular, the scope of the invention includes any and all feasible combinations of one or more of the processes, machines, manufacture, or compositions of matter set forth in the appended claims. (Note that parenthetical markings of claim elements are for convenience of reference to such elements and do not, by themselves, indicate a particular required order or enumeration of the elements; furthermore, such markings may be repeated in dependent claims as references to additional elements without being considered as starting a conflicting marking sequence).

Claims

1. A phase change material (PCM) driver for programming the state of a PCM switch, comprising: A PCM switch comprising a heater and a volume of phase change material coupled to the heater; a driver circuit connected to the heater and configured to provide a first electrical pulse profile or a second electrical pulse profile to the heater depending on a desired state to which the PCM switch is to be programmed; as well as A logic and control circuit coupled to the driver and configured to program the PCM switch by: When the PCM switch is to be programmed to a conducting state corresponding to the first electrical pulse profile, providing a first control pulse to the driver, and When the PCM switch is to be programmed to an off state corresponding to the second electrical pulse curve, a second control pulse is provided to the driver, The PCM switch, the driver and the logic and control circuit are integrated on the same chip.

2. The PCM driving device according to claim 1, wherein: The first electrical pulse profile corresponds to a first amount of power generated by the heater during a first time interval, and the second electrical pulse profile corresponds to a second amount of power generated by the heater during a second time interval.

3. The PCM driving device according to claim 2, wherein: The heater includes a heater resistor.

4. The PCM driving device according to claim 3, wherein: The driver circuit is configured to drive the heater by: providing a first driver pulse corresponding to the first control pulse, the first driver pulse having a first driver pulse amplitude and a first driver pulse width corresponding to the first time interval, and A second driver pulse is provided corresponding to the second control pulse, the second driver pulse having a second driver pulse amplitude and a second driver pulse width corresponding to the second time interval.

5. The PCM driving device according to claim 4, wherein: The first amount of power is a function of the first driver pulse amplitude and the heater resistor; and The second amount of power is a function of the second driver pulse amplitude and the heater resistor.

6. The PCM driving device according to claim 5, wherein: the second driver pulse amplitude is greater than the first driver pulse amplitude, and The second driver pulse width is smaller than the first driver pulse width.

7. The PCM driving device according to claim 5, wherein: The first driver pulse width and the second driver pulse width are programmable.

8. The PCM driving device according to claim 1, wherein: The driver circuit includes a first transistor stack configured to receive the first control pulse, and a second transistor stack configured to receive the second control pulse. 9 . The PCM driving device according to claim 8 , further comprising a first load device transistor arranged in series with the first transistor stack, and a second load device transistor arranged in series with the second transistor stack.

10. The PCM driving device according to claim 9, further comprising a first additional transistor arranged in series with the first load device transistor, and a second additional transistor arranged in series with the second load device transistor, the first additional transistor and the second additional transistor forming a quasi-latch circuit.

11. The PCM driving device according to claim 9, further comprising a feedback circuit configured to generate a set reference current for each of the on-state and the off-state of the PCM switch, and A current mirror is coupled to the feedback circuit, the current mirror being configured to drive: inputting a first reference current corresponding to the conduction state of the PCM switch, or A second reference current is input to the heater corresponding to the off state of the PCM switch.

12. The PCM switch of claim 1, further comprising a serial interface configured to provide input to the logic and control circuitry.

13. The PCM switch according to claim 12, wherein: The serial interface is implemented according to the Serial Peripheral Interface (SPI) or Mobile Industry Processor Interface (MIPI) standard.

14. A drive device for a phase change material (PCM) switch stack, comprising: a plurality of PCM switches, each PCM switch including a heater and a volume of PCM, the PCM switches being arranged in a stacked configuration; a plurality of drivers, each driver being configured to drive a corresponding PCM switch of the plurality of PCM switches; as well as A logic and control module is configured to drive the plurality of actuators in separate time intervals, one or more actuators at a time.

15. A method of programming a state of a phase change material (PCM) switch, the PCM switch comprising a heater and a volume of PCM, the method comprising: providing a driver circuit; Integrating the driver and the PCM switch on the same chip; applying a first control pulse to the driver circuit when the PCM switch is to be programmed to a conducting state; as well as When the PCM switch is to be programmed in the off state, a second control pulse is applied to the driver.

16. The method according to claim 15, further comprising: applying a first driver pulse to the PCM switch corresponding to the first control pulse by the driver circuit, and A second driver pulse is applied to the PCM switch by the driver circuit in correspondence with the second control pulse.

17. The method of claim 16, wherein: The amplitude of the second control pulse is greater than the amplitude of the first control pulse, and The width of the second control pulse is smaller than the width of the second control pulse.

18. The method according to claim 17, wherein: The width of the first control pulse and the width of the second control pulse are programmable.

19. The method of claim 18, further comprising controlling the amplitude of the first control pulse and the amplitude of the second control pulse through a feedback mechanism.

20. A method of programming a state of a phase change material (PCM) switch stack, the PCM switch stack comprising a plurality of PCM switches arranged in a stacked configuration, the method comprising actuating the plurality of PCM switches in separate time intervals, one or more PCM switches at a time.

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