Patent Description:
An input receiver in an integrated circuit (IC) functions to receive a signal external to the IC, determine logical states of the signal, and convert the signal into, for example, a rail-to-rail signal usable in the IC. Generally, in operation, the input receiver compares the signal to a reference signal, thereby determining the logical states of the signal. Next, the input receiver outputs either a voltage level representing a logically high state if the signal is higher than the reference voltage, or a voltage level representing a logically low state if the signal is lower than the reference voltage.

Typically, a greater difference of the voltage levels between a logically high state and a logically low state of the signal facilitates increased accuracy in the determination performed by the input receiver. However, in practice, the signal may be interfered with by a noise, which may cause the difference to be relatively insignificant. As a result, accuracy in the determination may be adversely affected.

From <CIT>, DC-DC converter includes an error generator, a mode selection reference voltage generator, an operation mode selector, and a driver controller. The error generator generates an error signal based on a direct-current output voltage. The mode selection reference voltage generator generates a first mode selection reference voltage and a second mode selection reference voltage lower than the first mode selection reference voltage. The first and second mode selection reference voltages vary based on amplitude of an alternating-current component included in the error signal. The operation mode selector compares the error signal with the first and second mode selection reference voltages. The driver controller switches a generating method of the direct-current output voltage from one of a PWM method and a PFM method to the other according to the result of the comparison.

According to <CIT>, a semiconductor device includes a reference circuit configured to generate a bias voltage, a regulator configured to generate a regulator output based on the bias voltage and a power supply voltage, an integrated circuit to which the regulator output is supplied as a power supply, and a reset circuit configured to detect whether a difference between the bias voltage and the power supply voltage is equal to or higher than a threshold voltage and output a reset signal based on a detection result.

In <CIT>, an improved interface circuit is described for translating a relatively high input voltage into a relatively low output voltage using only low voltage transistors and a single, low voltage power supply. According to one embodiment, the interface circuit includes a power supply, a pair of input transistors with source terminals coupled together for receiving a relatively low voltage from the power supply, and a current sense amplifier with a pair of input terminals, each coupled to a drain terminal of a different one of the pair of input transistors for receiving a pair of differential currents and for generating a pair of differential voltages therefrom.

This Discussion of the Background section is for background information only. The statements in this Discussion of the Background are not an admission that the subject matter disclosed in this section constitutes a prior art to the present disclosure, and no part of this section may be used as an admission that any part of this application, including this Discussion of the Background section, constitutes prior art to the present disclosure.

The invention is defined by the subject matter of claim <NUM>. One aspect of the present disclosure provides a semiconductor device. The semiconductor device includes a difference-expanding device and a receiver. The difference-expanding device is configured to receive a bias and an input signal having voltage levels representing logical states, and to convert the input signal to a processed signal by changing, based on a voltage difference between the bias and the input signal, degrees in conduction of the difference-expanding device. The receiver is configured to receive the processed signal from the difference-expanding device, and determine whether the input signal represents a logically low state or a logically high state based on the processed signal.

According to the invention, the difference-expanding device is configured to operate in a first conduction state in response to a first voltage level of the voltage levels. The difference-expanding device is configured to operate in a second conduction state in response to a second voltage level of the voltage levels. The first conduction state is less conductive than the second conduction state. The difference-expanding device is further configured to increase a distinctness of the first voltage level, wherein the first voltage level represents the first logical state.

According to the invention, when the first logical state is a logically low state, the difference-expanding device increases the distinctness of the first voltage level by decreasing the first voltage level, wherein the decreased first voltage level serves as a voltage level, which represents the logically low state, of the processed voltage.

According to the invention, the difference-expanding device includes a resistor and a p-type transistor. The resistor is coupled between the receiver and a reference ground. The p-type transistor includes a source receiving the input signal, and a drain coupled to both the resistor and the receiver.

According to the invention, when the first logical state is a logically high state, the difference-expanding device increases the distinctness of the first voltage level by increasing the first voltage level, wherein the increased first voltage level serves as a voltage level, which represents the logically high state, of the processed voltage.

According to the invention, the difference-expanding device includes a resistor and an n-type transistor. The resistor is coupled between the receiver and a supply voltage. The n-type transistor includes a source receiving the input signal, and a drain coupled to both the resistor and the receiver.

In some embodiments, the drain of the n-type transistor is directly coupled to the resistor and the receiver.

In the present disclosure, the difference of the voltage levels of the processed signal is relatively large compared to the difference of the voltage levels of the input signal. Even if there is noise in the processed signal, the adverse effect incurred by the noise compared to the relatively large difference of the voltage levels is insignificant and can be ignored. The receiver's accuracy in determining logical states is relatively high.

The foregoing has outlined rather broadly the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and technical advantages of the disclosure are described hereinafter, and form the subject of the claims of the disclosure. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the scope of the disclosure as set forth in the appended claims.

A more complete understanding of the present disclosure may be derived by referring to the detailed description and claims. The disclosure should also be understood to be connected to the figures' reference numbers, which refer to similar elements throughout the description.

<FIG> is a schematic diagram of a semiconductor device <NUM>, in accordance with the invention. Referring to <FIG>, the semiconductor device <NUM> comprises a difference-expanding device <NUM> and a receiver <NUM>.

According to the invention, the difference-expanding device <NUM> functions to receive an input signal Vin. The input signal Vin includes, for example, a clock signal, a data signal, an address signal, and other suitable signals. The input signal Vin has voltage levels representing logical states. In some embodiments, the difference-expanding device <NUM> functions to convert the input signal Vin to a processed signal Vp by changing, based on the voltage levels, degrees in conduction of the difference-expanding device <NUM>. In some embodiments, information in the processed signal Vp is maintained in the same manner as that in the input signal Vin, except that voltage levels representing logical states are changed. In some embodiments, by changing the degree of the conduction of the difference-expanding device <NUM>, a difference between a voltage level representing a logically high state and a voltage level representing a logically low state is expanded, which facilitates increased accuracy in determining information.

In some embodiments, the receiver <NUM> functions to receive the processed signal Vp from the difference-expanding device <NUM>, and compare the processed signal Vp to a reference voltage Vref, thereby outputting an output voltage Vout. In some embodiments, based on the comparison, the receiver <NUM> determines a logical state of the processed signal Vp, and provides the determination result in the output voltage Vout. In some embodiments, the receiver <NUM> includes a differential pair and a current mirror. The differential pair functions to receive the reference voltage Vref and the processed signal Vp.

In some existing DRAMs, a receiver directly receives an input signal, and compares the input signal to a reference voltage. However, the input signal may include noise, such that the receiver may not be able to correctly determine logical states of the input signal.

In the present disclosure, difference of voltage levels, which represents logical states, of the processed signal Vp is relatively large compared to that of the input signal Vin. In some embodiments, even if there is noise in the processed signal Vp, the adverse effect incurred by the noise compared to the relatively large difference in voltage levels representing logical states can be ignored; consequently, accuracy of the receiver <NUM> in determining logical states is relatively high.

<FIG> is a schematic diagram of another semiconductor device <NUM>, in accordance with the invention. Referring to <FIG>, the semiconductor device <NUM> is similar to the semiconductor device <NUM> described and illustrated with reference to <FIG> except that, for example, the semiconductor device <NUM> comprises a difference-expanding device <NUM> including a current source <NUM> and a resistor <NUM>.

In some embodiments, the current source <NUM>, coupled between the input signal Vin and the resistor <NUM>, functions to provide different currents to the resistor <NUM> in response to different voltage levels of the input signal Vin. In some embodiments, the current source <NUM> provides a first current to the resistor <NUM> in response to a first voltage level, which represents a logically high state of logical states of the input signal Vin, of the input signal Vin. In some embodiments, the current source <NUM> provides a second current to the resistor <NUM> in response to a second voltage level, which represents a logically low state of the logical states, of the input signal Vin. In some embodiments, the second current is significantly less than the first current.

In some embodiments, the resistor <NUM> functions to receive current from the current source <NUM>, and to provide the processed voltage Vp based on the current. In some embodiments, a voltage Vn1 at a tap n1 between the current source <NUM> and the resistor <NUM> serves as the processed signal Vp. In some embodiments, a voltage at one terminal of the resistor <NUM> serves as the processed signal Vp, and a voltage level at the other terminal of the resistor <NUM> is a reference ground.

In some embodiments, as previously mentioned, the second current is significantly less than the first current; therefore, a voltage across the resistor <NUM> based on the second current is negligible compared to that based on the first current. In some embodiments, when the second current is received, a voltage level, which represents the logically low state, of the processed signal Vp, substantially equals the reference ground. In some embodiments, when the second voltage level of the input signal Vin is about <NUM> mV (millivolts), a voltage level, which represents a logically low state, at the tap n1 is about <NUM> V. In some embodiments, similarly, when the second voltage level of the input signal Vin is about <NUM> mV, a voltage level, which represents a logically low state, at the tap n1 is still about <NUM> V.

In the present disclosure, the current source <NUM> provides the extremely small second current in response to the logically low state of the input signal Vin. Accordingly, when the input signal Vin is converted to the processed signal Vp, a voltage level, which represents the logically low state, of the processed signal Vp, is substantially equal to the reference ground. In some embodiments, in summary, the difference between a voltage level representing the logically high state and a voltage level representing the logically low state is expanded. In some embodiments, even if there is noise in the processed signal Vp, the adverse effect incurred by the noise compared to the relatively large difference in the voltage levels can be ignored; consequently, accuracy of the receiver <NUM> in determining logical states is relatively high.

<FIG> is a schematic diagram of still another semiconductor device <NUM>, in accordance with the invention. Referring to <FIG>, the semiconductor device <NUM> is similar to the semiconductor device <NUM> described and illustrated with reference to <FIG> except that, for example, the semiconductor device <NUM> comprises a difference-expanding device <NUM> including a p-type transistor M. In some embodiments, the p-type transistor M has a source S receiving the input signal Vin, a gate G receiving a bias voltage Vbias, and a drain D coupled to the tap n1 and an input of the receiver <NUM>.

In some embodiments, the p-type transistor M is a power field-effect transistor, such as a p-type metal-oxide-semiconductor (PMOS) field-effect transistor.

In some embodiments, the bias voltage Vbias is designed, depending on the input signal Vin, such that a difference between the first voltage level of the input signal Vin and the bias voltage Vbias is greater than a threshold voltage of the p-type transistor M.

In some embodiments, by way of a current-versus-voltage characteristic of a transistor, the p-type transistor M can provide different currents in response to different voltage levels of the input signal Vin, such that the difference of the voltage levels is expanded as previously mentioned. In some embodiments, even if there is noise in the processed signal Vp, the adverse effect incurred by the noise compared to the relatively large difference in the voltage levels can be ignored; consequently, accuracy of the receiver <NUM> in determining logical states is relatively high.

<FIG> is a schematic diagram illustrating an operation of the semiconductor device <NUM> shown in <FIG>, in accordance with some embodiments of the present disclosure. <FIG> is a schematic diagram illustrating another operation of the semiconductor device <NUM> shown in <FIG>, in accordance with some embodiments of the present disclosure. <FIG> is a waveform diagram illustrating the operations shown in <FIG> and <FIG>, in accordance with some embodiments of the present disclosure.

In the present embodiment, the semiconductor device <NUM> serves as a device of a DDR4 (double data rate <NUM>). As a result, there is a self-training mechanism on the reference voltage Vref of the receiver <NUM>. The reference voltage Vref is continually trained (or dynamically adjusted) to an optimal voltage between a voltage level, which represents a logically high state, and a voltage level, which represents a logically low state. In some embodiments, the optimal voltage includes a middle voltage between a voltage level, which represents a logically high state, and a voltage level, which represents a logically low state. However, the present disclosure is not limited thereto. For convenience of discussion, in the following discussion, the optimal voltage refers to the middle voltage.

Referring to <FIG>, for better understanding the operation of the semiconductor device <NUM> shown in <FIG>, some values are provided. However, such values serve only as an example, and the present disclosure is not limited thereto. Assume that the first voltage level of the input signal Vin is about <NUM> mV, the second voltage level is about <NUM> mV, the bias voltage Vbias is about <NUM> mV, and the threshold voltage of the p-type transistor M is about <NUM> mV. Moreover, generally, the reference voltage Vref is set at a middle voltage between the first voltage level and the second voltage level, i.e., about <NUM> mV.

In operation, referring to <FIG> and <FIG>, a source-to-gate voltage Vsg of the p-type transistor M is about <NUM> mV, which is greater than the threshold voltage of the p-type transistor M. Therefore, the p-type transistor M conducts well, exhibits a relatively small resistance, and provides a relatively large current to the resistor <NUM>. Because of the relatively small resistance, the p-type transistor M and the resistor <NUM> slightly decrease the first voltage level of about <NUM> mV of the input signal Vin by a first degree of about <NUM> mV, and provide about <NUM> mV of the voltage Vn1 at the tap n1. The voltage Vn1 of <NUM> mV serves as the processed signal Vp, and represents a logically high state.

Additionally, in operation, referring to <FIG> and <FIG>, the source-to-gate voltage Vsg of the p-type transistor M is about <NUM> mV, which is less than the threshold voltage of the p-type transistor M. Accordingly, the p-type transistor M is in, for example, a cut-off region. Therefore, the p-type transistor M does not conduct, exhibits a relatively large resistance, and provides no current, or an extremely small current, to the resistor <NUM>. Because no current is provided, the p-type transistor M and the resistor <NUM> significantly decrease the second voltage level of about <NUM> mV of the input signal Vin by a second degree of about <NUM> mV, and provide about <NUM> mV of the voltage Vn1 at the tap n1. The voltage Vn1 of <NUM> mV serves as the processed signal Vp, and represents a logically low state. That is, the p-type transistor M and the resistor <NUM> increase the distinctness of the second voltage level by decreasing the second voltage level when the p-type transistor M conducts relatively poorly.

In summary, the p-type transistor M operates in a first conduction state in response to a logically low state. In addition, the p-type transistor M operates in a second conduction state in response to a logically high state. The first conduction state is less conductive than the second conduction state. The p-type transistor M and the resistor <NUM> increase the distinctness of a voltage that represents a logically low state.

Regarding the input signal Vin, a voltage difference Vdiff1 between the first voltage level and the second voltage level is about <NUM> mV. A voltage difference Vmh between the reference voltage Vref and the first voltage level is about <NUM> mV. A voltage difference Vml between the reference voltage Vref and the second voltage level is about <NUM> mV.

Regarding the processed signal Vp, a voltage difference Vdiff2 between a voltage level, which represents a logically high state, and a voltage level, which represents logically low state, is about <NUM> mV. Moreover, in such case, due to the function of the self-training mechanism, the reference voltage Vref is adjusted from about <NUM> mV to about <NUM> mV. Accordingly, a voltage difference Vmh1 between the reference voltage Vref and a voltage level, which represents a logically high state, of the processed signal Vp is <NUM> mV. In addition, a voltage difference Vml1 between the reference voltage Vref and a voltage level, which presents a logically low state, of the processed signal Vp is <NUM> mV.

Compared to the voltage difference Vdiff1, the voltage difference Vml and the voltage difference Vmh, respectively, the voltage difference Vdiff2, the voltage difference Vml1 and the voltage difference Vmh1 are relatively large. As a result, even if there is noise in the processed signal Vp, the adverse effect incurred by the noise compared to the relatively large difference in the voltage levels can be ignored; consequently, accuracy of the receiver <NUM> in determining logical states is relatively high.

<FIG> is a waveform diagram illustrating a suboptimal operation of the semiconductor device <NUM> shown in <FIG>, in accordance with some embodiments of the present disclosure. Referring to <FIG> a first voltage level of the input signal Vin is about <NUM> mV, and a second voltage level of the input signal Vin is about <NUM> mV. A voltage difference Vdiff1 therebetween is only about <NUM> mV, which is relatively small and may lead to higher likelihood of incorrectly determining logical states by the receiver <NUM>.

In the present disclosure, with the difference-expanding device <NUM>, the second voltage level of the input signal Vin is reduced significantly from about <NUM> mV to about <NUM> mV. On the other hand, the first voltage level of the input signal Vin is slightly reduced from about <NUM> mV to about <NUM> mV. A voltage difference Vdiff2 is about <NUM> mV. A voltage difference increases from the voltage difference Vdiff1 of about <NUM> mV to the voltage difference Vdiff2 of about <NUM> mV, which is a relatively large increase.

In summary, even if the input signal Vin is suboptimal, with the difference-expanding device <NUM>, the difference of the voltage levels is expanded as described above; consequently, accuracy of the receiver <NUM> in determining logical states in the worst case is relatively high.

<FIG> is a waveform diagram illustrating another operation associated with the embodiment of <FIG>, in accordance with some embodiments of the present disclosure. Referring to <FIG>, similar to the embodiment of <FIG>, the semiconductor device <NUM> serves as a device of a DDR4. As a result, the voltage difference Vml1 becomes about <NUM> mV, which is greater than the voltage difference Vml of about <NUM> mV. Moreover, a voltage difference Vmh1 is about <NUM> mV, which is greater than the voltage difference Vmh of about <NUM> mV. As a result, even if there is noise in the processed signal Vp, the adverse effect incurred by the noise compared to the relatively large difference in the voltage levels can be ignored; consequently, accuracy of the receiver <NUM> in determining logical states is relatively high.

<FIG> is a schematic diagram of further another semiconductor device <NUM>, in accordance with some embodiments of the present disclosure. Referring to <FIG>, the semiconductor device <NUM> is similar to the semiconductor device <NUM> described and illustrated with reference to <FIG> except that, for example, the semiconductor device <NUM> includes a difference-expanding device <NUM>.

The difference-expanding device <NUM> includes an n-type transistor Mn and a resistor <NUM>. The n-type transistor Mn includes a source Sn receiving an input signal Vin, a gate Gn receiving a bias voltage Vbias and a drain Dn coupled to an input of the receiver <NUM>. The resistor <NUM> is coupled between a supply voltage VDD and the input of the receiver <NUM>.

Operation of the difference-expanding device <NUM> is similar to that of the difference-expanding device <NUM>. Descriptions of similar details are therefore omitted herein. Briefly, in response to the second voltage level of the input signal Vin, the n-type transistor Mn conducts relatively well, and provides a relatively large current to the resistor <NUM>. The n-type transistor Mn and the resistor <NUM> slightly increase the second voltage level of the input signal Vin. That is, a voltage level, which represents a logically low state, of the processed signal Vp is slightly higher than the second voltage level of the input signal Vin.

In contrast, in response to the first voltage level of the input signal Vin, the n-type transistor Mn conducts relatively poorly, and the n-type transistor Mn provides a relatively small current to the resistor <NUM>. Because of the relatively small current, a voltage across the resistor <NUM> is substantially negligible. The n-type transistor Mn and resistor <NUM> significantly increase the first voltage level of the input signal Vin. The increased first voltage level substantially equals the supply voltage VDD. That is, the voltage level, which represents a logically high state, of the processed signal Vp is significantly higher than the first voltage level of the input signal Vin. As a result, the n-type transistor Mn and the resistor <NUM> increase the distinctness of the first voltage level by increasing the first voltage level when the n-type transistor Mn conducts relatively poorly. As a result, the difference between the voltage levels is expanded, as described above. In some embodiments, even if there is noise in the processed signal Vp, the adverse effect incurred by the noise compared to the relatively large difference in the voltage levels can be ignored; consequently, accuracy of the receiver <NUM> in determining logical states is relatively high.

<FIG> is a flowchart illustrating a method <NUM> of operating a semiconductor device, in accordance with some embodiments of the present disclosure. In some embodiments, referring to <FIG>, the method <NUM> includes operations <NUM>, <NUM> and <NUM>.

In some embodiments, the method <NUM> begins with operation <NUM>, in which an input signal having voltage levels representing logical states is received.

In some embodiments, the method <NUM> proceeds to operation <NUM>, in which the input signal is converted to a processed signal by changing degrees in conduction of a difference-expanding device based on the voltage levels.

In some embodiments, the method <NUM> continues with operation <NUM>, in which the processed signal is provided to a receiver of the semiconductor device by the difference-expanding device.

The method <NUM> is merely an example, and is not intended to limit the present disclosure beyond what is explicitly recited in the claims. Additional operations can be provided before, during, and after the method <NUM>, and some operations described can be replaced, eliminated, or moved around for additional embodiments of the method.

In the present disclosure, by changing the degrees in the conduction of the difference-expanding device <NUM>, a difference between a voltage level representing a logically high state and a voltage level representing a logically low state is expanded, which facilitates increased accuracy in determining information.

In some existing DRAMs, a receiver directly receives an input signal, and compares the input signal to a reference voltage. However, there may be noise in the input signal, such that the receiver may not be able to correctly determine logical states of the input signal.

In the present disclosure, the difference of the voltage levels of the processed signal Vp is relatively large compared to the difference of the voltage levels of the input signal Vin. Even if there is noise in the processed signal Vp, the adverse effect incurred by the noise compared to the relatively large difference in the voltage levels can be ignored; consequently, accuracy of the receiver <NUM> in determining logical states is relatively high.

Claim 1:
A semiconductor device (<NUM>, <NUM>, <NUM>, <NUM>), comprising:
a difference-expanding device (<NUM>, <NUM>, <NUM>) configured to receive a bias voltage and an input signal having a first voltage level representing a first logical state and a second voltage level representing a second logic state, and convert the input signal to a processed signal by changing, based on a voltage difference between the bias voltage and the input signal, degrees in conduction of the difference-expanding device (<NUM>, <NUM>, <NUM>), wherein the difference-expanding device comprises:
a transistor having a source receiving the input signal, a drain, and a gate receiving the bias voltage; and;
a resistor having a first terminal coupled to the drain, and a second terminal receiving a reference ground or a supply voltage; and
a receiver (<NUM>) coupled to the drain of the transistor, and configured to receive the processed signal from the difference-expanding device (<NUM>, <NUM>, <NUM>), and determine whether the input signal represents a logically low state or a logically high state based on the processed signal.