A system and method for testing AC parameters of a low-voltage differential driver.

Abstract

This application discloses an AC parameter testing system and method for a low-voltage differential driver. The system includes: a pulse generation module coupled to a pulse output module for generating pulse signals; a pulse output module coupled to a pulse parameter measurement module and the low-voltage differential driver for sending the pulse signals to the pulse parameter measurement module and the low-voltage differential driver; a pulse parameter measurement module for measuring a first AC parameter of the pulse signal; a low-voltage differential driver coupled to a differential output parameter measurement module for measuring a second AC parameter corresponding to the low-voltage differential driver; and a compensation module coupled to the pulse parameter measurement module and the differential output parameter measurement module for calculating the compensated AC parameters corresponding to the low-voltage differential driver based on the first AC parameter and the second AC parameter. This application solves the technical problem that existing AC parameter testing schemes cannot meet practical needs.

Description

Technical Field

[0001] This application relates to the field of integrated circuit testing technology, and in particular to an AC parameter testing system and method for a low-voltage differential driver. Background Technology

[0002] Low-voltage differential drivers, as high-speed interface driver circuits, are used to convert single-ended CMOS signals into low-voltage differential signals to meet the requirements of high-speed and high-reliability transmission. The typical common-mode voltage of a low-voltage differential signal is approximately 1.25V, and the differential-mode voltage is approximately 350mV. Due to the small swing and strong immunity to common-mode interference of differential signals, they are mainly used for high-speed data transmission over short distances within and between boards. AC parameters are an important type of parameter specification for integrated circuits and are mandatory testing items in integrated circuit screening. For high-speed integrated circuits, AC parameter specifications are particularly important. The main AC parameters of low-voltage differential drivers include: output signal rise time Tr, output signal fall time Tf, and output signal propagation delay, such as the high-to-low propagation delay Tphl, low-to-high propagation delay Tplh, high-to-low propagation delay Tpzl, high-to-high propagation delay Tpzh, low-to-high propagation delay Tplz, high-to-high propagation delay Tphz, propagation delay offset Tskd, and channel / device offset Tsk, etc. The general requirements for AC parameter testing in integrated circuit test standards (or device datasheets) are: for propagation delay parameters, the measurement should start from the input signal changing to 50% of Vin voltage and continue until the output signal changes to (Vol+Voh) / 2; for rise (fall) time, the measurement should be taken from 20% to 80% of the output voltage (or from 80% to 20%).

[0003] Currently, in integrated circuit screening and testing, AC parameters are generally tested using Automatic Test Equipment (ATE). When using ATE, dedicated TMU or TIA instruments can be used to test AC parameters. The principle is to use the transition point of the input signal as a reference time point, and then set a reference criterion for the output voltage. The relative time it takes for the output voltage to change from high to low (or from low to high) through this reference voltage is collected, and this is used as the test result. However, when testing AC parameters using the ATE's TIA or TMU, the main errors come from the following two aspects:

[0004] 1) Test standards (or device manuals) generally require that the starting timing point be when the input signal reaches 50% of its high voltage, while ATE uses the starting point of the input signal change as the starting timing point. There is a 50% difference between the two input signal transition time.

[0005] The factors affecting the input signal transition time mainly include two aspects: first, the driving capability of the ATE signal source; and second, the influence of parasitic parameters of the test load board circuitry and test fixtures. The driving capability of the ATE signal source can be obtained by consulting ATE technical documentation, while the influence of parasitic parameters of the test load board is related to the specific hardware design. In actual testing, the measured input signal transition time provided by the ATE to the circuit under test is approximately 1ns-2ns, with 50% of this being 0.5ns-1ns. For low-speed circuits, this error will not significantly affect the final test results, but for high-speed circuits such as low-voltage differential drivers, its impact cannot be ignored.

[0006] 2) When using ATE to measure AC parameters, a voltage value needs to be set for the output signal as the criterion for the end of the time measurement. For general single-ended circuits, such as integrated circuits with a 3.3V CMOS level standard, the high voltage of the output signal is normally around 3.3V under no current load conditions, with minimal deviation. Therefore, 3.3V / 2 can be directly used as the criterion for measuring AC parameters.

[0007] For low-voltage differential drivers, the datasheet specifies that 50% of the output differential voltage VOD (the differential voltage of a set of output ports of the low-voltage differential driver, also called differential-mode voltage) should be used as the measurement criterion for AC parameters. Due to limitations in chip manufacturing processes, the VOD of different circuits, or even different differential channels of the same circuit, generally varies to some extent. For example, an output VOD between 247mV and 454mV is considered acceptable (typically around 350mV). Since the VOD given in the datasheet is not a relatively accurate value, it cannot be used as the measurement criterion for AC parameters in actual testing. Using its lower limit will introduce significant errors in the measurement results, while using its upper limit will result in no test results because some channels cannot reach the specified VOD. Summary of the Invention

[0008] The technical problem addressed by this application is that existing AC parameter testing schemes cannot meet practical needs. This application provides an AC parameter testing system and method for low-voltage differential drivers. The solution provided in this application introduces a compensation module when measuring the AC parameters corresponding to the low-voltage differential driver. This compensation module compensates for the test results of the AC parameters corresponding to the low-voltage differential driver, effectively solving the test error caused by the 50% transition time of the input signal. Furthermore, compared to directly using the TMU and TIA in ATE instruments to test the AC parameters of the low-voltage differential driver, the test results of this application's embodiments better meet the product manual's test requirements and are more accurate.

[0009] In a first aspect, embodiments of this application provide an AC parameter testing system for a low-voltage differential driver. This system includes: a pulse generation module, a pulse output module, a pulse parameter measurement module, a low-voltage differential driver, a differential output parameter measurement module, and a compensation module; wherein...

[0010] The pulse generation module is coupled to the pulse output module and is used to generate pulse signals;

[0011] The pulse output module is coupled to the pulse parameter measurement module and the low voltage differential driver, and is used to send the pulse signal to the pulse parameter measurement module and the low voltage differential driver;

[0012] The pulse parameter measurement module is used to measure the first AC parameter of the pulse signal;

[0013] The low-voltage differential driver and the differential output parameter measurement module are used to output a differential signal based on the pulse signal;

[0014] The differential output parameter measurement module is used to measure the second AC parameter of the differential signal;

[0015] The compensation module is coupled to the pulse parameter measurement module and the differential output parameter measurement module, and is used to calculate the compensated AC parameters corresponding to the low voltage differential driver based on the first AC parameter and the second AC parameter.

[0016] Optionally, the pulse signal generated by the pulse generation module includes a positive pulse signal from an input low-level voltage to an input high-level voltage and a negative pulse signal from an input high-level voltage to an input low-level voltage.

[0017] Optionally, the pulse output module includes a set of input ports, a first set of output ports, and a second set of output ports; wherein the input ports and the first set of output ports constitute a first channel, and the input ports and the second set of output ports constitute a second channel; the first channel is used to send the pulse signal to the pulse parameter measurement module, and the second channel is used to send the pulse signal to the low-voltage differential driver.

[0018] Optionally, the pulse output module sends the pulse signal to the pulse parameter measurement module through the first channel at a specified time; or sends the pulse signal to the low-voltage differential driver through the second channel.

[0019] Optionally, the low-voltage differential driver includes at least one differential output port; the differential output parameter measurement module includes a DC parameter measurement submodule and an AC parameter measurement submodule; wherein the DC parameter measurement submodule is coupled to the low-voltage differential driver and the AC parameter measurement submodule, and is used to measure the DC output voltage of each differential output port; the AC parameter measurement submodule is used to calculate the corresponding AC output voltage based on the DC output voltage of each differential output port.

[0020] Optionally, each differential output port includes a positive output port and a negative output port; the DC output voltage includes the output high voltage Voh_y, output low voltage Vol_y, and output tri-state bias voltage Voz_y of the positive output port in each differential output port; and the output high voltage Voh_z, output low voltage Vol_z, and output tri-state bias voltage Voz_z of the negative output port in each differential output port.

[0021] Optionally, the AC parameter measurement submodule calculates the rise time, fall time, and transmission delay of the output signal of the positive output port based on the output high voltage Voh_y, output low voltage Vol_y, and output tri-state pull-up voltage Voz_y of the positive output port in each differential output port; and calculates the rise time, fall time, and transmission delay of the output signal corresponding to the reverse output port based on the output high voltage Voh_z, output low voltage Vol_z, and output tri-state pull-up voltage Voz_z of the reverse output port in each differential output port.

[0022] Optionally, the pulse generation module, the pulse parameter measurement module, and the AC parameter measurement submodule are clock-synchronized.

[0023] Secondly, embodiments of this application provide a method for testing the AC parameters of a low-voltage differential driver, the method comprising:

[0024] The pulse generation module generates a pulse signal and sends the pulse signal to the pulse output module and the pulse parameter measurement module;

[0025] The pulse output module receives the pulse signal and sends the pulse signal to the pulse parameter measurement module and the low voltage differential driver;

[0026] The pulse parameter measurement module receives the pulse signal, measures the first AC parameter of the pulse signal, and sends the first AC parameter to the compensation module.

[0027] The low-voltage differential driver receives the pulse signal, outputs a differential signal based on the pulse signal, and sends the differential signal to the differential output parameter measurement module;

[0028] The differential output parameter measurement module receives the differential signal and measures a second AC parameter of the differential signal, and sends the second AC parameter to the compensation module;

[0029] The compensation module calculates the compensated AC parameters corresponding to the low-voltage differential driver based on the first AC parameter and the second AC parameter.

[0030] Optionally, the differential output parameter measurement module includes a DC parameter measurement submodule and an AC parameter measurement submodule; wherein, the differential output parameter measurement module receives a differential signal and measures a second AC parameter of the differential signal, and sends the second AC parameter to the compensation module, including: the DC parameter measurement submodule measures the DC output voltage of each differential output port; the AC parameter measurement submodule calculates the corresponding AC output voltage based on the DC output voltage of each differential output port.

[0031] Compared with the prior art, the solution provided in this application has at least the following beneficial effects:

[0032] 1. The solution provided in this application introduces a compensation module when measuring the AC parameters corresponding to the low-voltage differential driver. This compensation module compensates for the test results of the AC parameters corresponding to the low-voltage differential driver, effectively solving the test error caused by the 50% transition time of the input signal. Furthermore, compared to directly using the TMU and TIA in an ATE instrument to test the AC parameters of the low-voltage differential driver, the test results of this application's embodiment better meet the product manual's test requirements and are more accurate.

[0033] 2. The solution provided in this application, when measuring the output AC parameters of a low-voltage differential driver, connects a DC parameter measurement submodule and an AC parameter measurement submodule to the differential output port of the low-voltage differential driver. The reference voltage for the AC parameters of the output signal of the AC parameter measurement submodule is calculated using the DC parameters of the output signal from the DC parameter measurement submodule. In other words, the AC parameter test conditions are specifically set using the DC parameter test results, effectively solving the problem of test consistency and stability between different channels (differential output ports) of the low-voltage differential driver. Attached Figure Description

[0034] Figure 1 A schematic diagram of an AC parameter testing system for a low-voltage differential driver provided in an embodiment of this application;

[0035] Figure 2 This application illustrates a circuit diagram of measuring AC parameters using a TMU or TIA instrument, as provided in an embodiment of the present application.

[0036] Figure 3 A flowchart illustrating an AC parameter testing method for a low-voltage differential driver provided in an embodiment of this application;

[0037] Figure 4 A simplified flowchart of an AC parameter testing method for a low-voltage differential driver provided in an embodiment of this application. Detailed Implementation

[0038] The embodiments described in this application are only a part of the embodiments, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0039] To better understand the above technical solutions, the technical solutions of this application will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments of this application and the specific features in the embodiments are detailed descriptions of the technical solutions of this application, rather than limitations on the technical solutions of this application. In the absence of conflict, the embodiments of this application and the technical features in the embodiments can be combined with each other.

[0040] Figure 1 A schematic diagram of an AC parameter testing system for a low-voltage differential driver provided in an embodiment of this application is shown.

[0041] As an example, in Figure 1 The AC parameter testing system includes: a pulse generation module 101, a pulse output module 102, a pulse parameter measurement module 103, a low-voltage differential driver 104, a differential output parameter measurement module 105, and a compensation module 106. The pulse generation module 101, coupled to the pulse output module 102, generates a pulse signal. The pulse output module 102, coupled to the pulse parameter measurement module 103 and the low-voltage differential driver 104, sends the pulse signal to these modules. The pulse parameter measurement module 103 measures a first AC parameter of the pulse signal. The low-voltage differential driver 104, coupled to the differential output parameter measurement module 105, outputs a differential signal based on the pulse signal. The differential output parameter measurement module 105 measures a second AC parameter of the differential signal. The compensation module 106, coupled to the pulse parameter measurement module 103 and the differential output parameter measurement module 105, calculates the compensated AC parameters corresponding to the low-voltage differential driver based on the first and second AC parameters.

[0042] As another example, the pulse generation module 101 is used to generate input pulse signals for testing the AC parameters of the low-voltage differential driver 104 (or the circuit under test). The voltage amplitude and frequency (or pulse width) of this pulse signal can be controlled, for example, by software programming; the pulse signal generated by the pulse generation module includes positive pulse signals from input low-level voltage to input high-level voltage and negative pulse signals from input high-level voltage to input low-level voltage. In addition, this pulse signal needs to be input to the subsequent low-voltage differential driver 104 for measuring the output AC parameters of the low-voltage differential driver 104. Therefore, the number of pulse channels of the input pulse signal can cover the input port A and output enable port G / nG of the low-voltage differential driver 104.

[0043] As another example, the pulse output module 102 is used to select a transmission path for the pulse signal generated by the pulse generation module 101, such as sending the pulse signal to the pulse parameter measurement module 103 or sending the pulse signal to the low-voltage differential driver 104. That is, the pulse output module 102 can send the pulse signal to two different modules or circuits (pulse parameter measurement module 103 or low-voltage differential driver 104). Therefore, the pulse output module 102 includes at least one input port and two sets of output ports. For example, the pulse output module 102 includes at least one set of input ports and two sets of output ports, such as output port A and output port B; wherein, the input port and output port A form channel C1, and the input port and output port B form channel C2; channel C1 is used to send the pulse signal to the pulse parameter measurement module 103, and channel C2 is used to send the pulse signal to the low-voltage differential driver 104. Specifically, the input port of the pulse output module 102 is connected to the output port of the pulse generation module 101.

[0044] As another example, the pulse output module 102 sends a pulse signal to the pulse parameter measurement module 103 via channel C1 at a specified time; or sends a pulse signal to the low-voltage differential driver 104 via channel C2. That is, either of the two sets of channels can be selected under software control, and only one set of output channels can be selected at a time.

[0045] Furthermore, the solution provided in this application embodiment is for compensating the AC parameters of the output signal of the low-voltage differential driver 104. Figure 1The test system shown also includes a pulse parameter measurement module 103. The input to the pulse parameter measurement module 103 is the pulse signal generated by the pulse generation module 101, and the output is the AC parameters corresponding to the pulse signal. For example, the pulse parameter measurement module 103 is used to measure the rise time of the pulse generated by the pulse generation module 101. Specifically, the pulse parameter measurement module 103 has a set of test pulse detection input ports, which can use the TMU instrument or TIA instrument of the ATE equipment to test the rise time Tr and fall time Tf of the input pulse signal. The test reference voltage for Tr / Tf of the input pulse signal can be set by software; the test time resolution can also be set by software. The test results (AC parameters of the pulse signal) of the pulse parameter measurement module 103 are given to the subsequent compensation module 106.

[0046] Furthermore, as an example, the low-voltage differential driver 104 includes at least one differential output port; for instance, the low-voltage differential driver 104 includes one or more single-ended input ports A, output enable ports G / nG, and one or more differential output ports Y (forward) and Z (reverse), that is, each differential output port includes a forward output port and a reverse output port. Since the input pulse signal of the low-voltage differential driver 104 is generated by the pulse generation module 101, the number of channels for transmitting pulse signals can cover the input port A and the output enable port G / nG of the low-voltage differential driver 104.

[0047] In addition, to ensure the consistency and stability of testing across different channels (differential output ports) of the low-voltage differential driver 104, the differential output parameter measurement module 105 includes, for example, a DC parameter measurement submodule 107 and an AC parameter measurement submodule 108. The DC parameter measurement submodule 107 is coupled to both the low-voltage differential driver 104 and the AC parameter measurement submodule 108, and is used to measure the DC output voltage of each differential output port. For example, the DC output voltage includes the output high voltage Voh_y, output low voltage Vol_y, and output tri-state bias voltage Voz_y of the positive output port in each differential output port; and the output high voltage Voh_z, output low voltage Vol_z, and output tri-state bias voltage Voz_z of the reverse output port in each differential output port.

[0048] The AC parameter measurement submodule 108 is used to calculate the corresponding AC output voltage based on the DC output voltage of each differential output port. For example, the AC parameter measurement submodule 108 calculates the rise time, fall time, and propagation delay of the output signal at the positive output port based on the high output voltage Voh_y, low output voltage Vol_y, and three-state bias voltage Voz_y of the positive output port in each differential output port; and calculates the rise time, fall time, and propagation delay of the output signal at the reverse output port based on the high output voltage Voh_z, low output voltage Vol_z, and three-state bias voltage Voz_z of the reverse output port in each differential output port. For example, the AC parameters of the pulse signal are tested using a TMU or TIA instrument, including rise time Tr, fall time Tf, and propagation delay Tphl / Tplh / Tpzl / Tpzh / Tplz / Tphz; the AC parameter test reference voltage is calculated from the measurement results of the DC parameter measurement submodule 107 and can be set by software; the test time resolution can be set by software; the test results of the AC parameter measurement submodule 108 are given to the AC parameter measurement result compensation module 106.

[0049] Specifically, based on the DC parameters of each differential output port Y / Z measured by the DC parameter measurement submodule 107, the reference voltage for the AC parameter test of each channel is calculated. For example, the low-voltage differential driver 104 includes three differential output ports, namely Y1 / Z1, Y2 / Z2, Y3 / Z3, Y4 / Z4, and Y5 / Z5. Then, the reference voltage of channel Tr corresponding to Y1 is Vol_y + (Voh_y - Vol_y) × 0.2 and Vol_y+(Voh_y-Vol_y)×0.8; the reference voltage of channel Tr corresponding to Z1 is Vol_z+(Voh_z-Vol_z)×0.2 and Vol_z+(Voh_z-Vol_z)×0.8; the reference voltage of channel Tf corresponding to Y2 is Voh_y-(Voh_y-Vol_y)×0.8 and Voh_y-(Voh_y-Vol_y)×0.2; The reference voltages for channel Tr corresponding to Z2 are Voh_z - (Voh_z - Vol_z) × 0.8 and Voh_z - (Voh_z - Vol_z) × 0.2; the reference voltages for channels Tphld and Tplhd corresponding to Y3 are (Voh_y - Vol_y) × 0.5; the reference voltages for channels Tphld and Tplhd corresponding to Z3 are (Voh_z - Vol_z) × 0.5; the reference voltages for channels Tphld and Tplhd corresponding to Z3 are (Voh_z - Vol_z) × 0.5; the reference voltages for channels Tphld and Tplhd corresponding to Y4 are (Voh_z - Vol_z) × 0.5; The reference voltages for channels Tpzh and Tphz are (Voh_y - Voz_y) × 0.5; the reference voltages for channels Tpzh and Tphz corresponding to Z4 are (Voh_z - Voz_z) × 0.5; the reference voltages for channels Tpzl and Tplz corresponding to Y5 are (Voz_y - Vol_y) × 0.5; and the reference voltages for channels Tpzl and Tplz corresponding to Z5 are (Voz_z - Vol_z) × 0.5.

[0050] In the above Figure 1 In the system shown, the pulse parameter measurement module 103 and the AC parameter measurement submodule can use the TMU or TIA instrument in the ATE instrument to measure AC parameters. The process of measuring AC parameters using the TMU or TIA instrument in the ATE instrument in this embodiment is briefly described below.

[0051] Figure 2 This application illustrates a circuit diagram for measuring AC parameters using a TMU or TIA instrument, as provided in an embodiment of the present application.

[0052] As an example, in Figure 2In this circuit, the main components include an ATE tester and a Loadboard test board. The ATE tester mainly consists of a main control computer, support instruments, DC power supply instruments, and digital channel instruments. The main control computer is the core unit for instrument control, test signal graph generation, and data aggregation and analysis. The support instruments mainly implement power supply and switching control of the relay matrix. The DC power supply instruments power the device under test (DUT). The digital channels are mainly divided into three groups, labeled A, B, and C in the diagram. Group A contains the test input signals (relative to the DUT), used to power the DUT (as described above). Figure 1 The low-voltage differential driver 104 shown provides test input pulses, including ports A, G, and nG; group B is the test output signal used to acquire AC parameters of the device under test, including ports Y and Z; group C is also the test output signal used to acquire AC parameters of the output signal of digital channel A, including ports A, G, and nG.

[0053] The loadboard test board mainly includes the device under test (DUT) and the relay array. In addition, the differential output terminals Y / Z of the DUT need to be connected to necessary resistors, capacitors, and the Vos bias power supply. Figure 2 (Not marked in the text).

[0054] Figure 2 The specific working process of the circuit shown is as follows:

[0055] (1) The main control computer sends instructions to the supporting instrument to control the supporting instrument to power on the relay matrix Relay, and at the same time switch the signal output of Relay to digital channel C.

[0056] (2) The main control computer controls digital channel A to send a pulse signal. The pulse amplitude is the amplitude Vih required for the AC parameter test of the circuit under test (DUT). At the same time, it controls digital channel C to collect the AC parameters when the pulse signal reaches 50% Vih, including the positive pulse rise time Tr_A_50p / Tr_G_50p and the negative pulse fall time Tf_A_50p / Tf_G_50p. When there are multiple inputs A, the time parameters of each channel must be measured separately.

[0057] (3) The main control computer sends instructions to the support instrument to control the support instrument to switch the signal output of the Relay to the device under test (DUT).

[0058] (4) The main control computer controls digital channel A to apply a high level to the G port of the DUT, a low level to the nG port, and a high level to the A port. At the same time, it controls digital channel B to collect the voltages of the output ports Y and Z of the device under test (DUT), which are recorded as Voh_y and Vol_z. When there are multiple inputs Y / Z, each output voltage must be measured separately.

[0059] (5) The main control computer controls digital channel A to apply a high level to the G port of the DUT, a low level to the nG port, and a low level to the A port. At the same time, it controls digital channel B to collect the voltages of the output ports Y and Z of the device under test (DUT), which are recorded as Vol_y and Voh_z. When there are multiple inputs Y / Z, each output voltage must be measured separately.

[0060] (6) The main control computer controls digital channel A to apply a high level to the G port of the DUT, a low level to the nG port, and a positive pulse to the A port. The pulse amplitude meets the test requirements of the DUT AC parameters. At the same time, it controls digital channel B to acquire data.

[0061] a) The times when the output port Y of the device under test (DUT) reaches Vol_y+(Voh_y-Vol_y)×0.2, Vol_y+(Voh_y-Vol_y)×0.5, and Vol_y+(Voh_y-Vol_y)×0.8 respectively are denoted as Tr_y_20p, Tr_y_50p, and Tr_y_80p. When there are multiple inputs Y / Z, the time parameter of each channel must be measured separately.

[0062] b) The times when the output port Z of the device under test (DUT) reaches Vol_z+(Voh_z-Vol_z)×0.8, Vol_z+(Voh_z-Vol_z)×0.5, and Vol_z+(Voh_z-Vol_z)×0.2 respectively are denoted as Tf_z_80p, Tf_z_50p, and Tf_z_20p. When there are multiple input Y / Z channels, the time parameter of each channel must be measured separately.

[0063] (7) The main control computer controls digital channel A to apply a high level to the G port of the DUT, a low level to the nG port, and a negative pulse to the A port. The pulse amplitude meets the test requirements of the DUT AC parameters. At the same time, it controls digital channel B to collect data.

[0064] 1) The times when the output port Y of the device under test (DUT) reaches Vol_y+(Voh_y-Vol_y)×0.8, Vol_y+(Voh_y-Vol_y)×0.5, and Vol_y+(Voh_y-Vol_y)×0.2 respectively are denoted as Tf_y_80p, Tf_y_50p, and Tf_y_20p. When there are multiple input Y / Z channels, the time parameter of each channel must be measured separately.

[0065] 2) The times when the output port Z of the device under test (DUT) reaches Vol_z+(Voh_z-Vol_z)×0.2, Vol_z+(Voh_z-Vol_z)×0.5, and Vol_z+(Voh_z-Vol_z)×0.8 respectively are denoted as Tr_z_20p, Tr_z_50p, and Tr_z_80p. When there are multiple input Y / Z channels, the time parameter of each channel must be measured separately.

[0066] (8) The main control computer calculates Tr, Tf, Tphld, and Tplhd as follows. When there are multiple differential drive channels, the time parameters of each channel must be calculated separately according to their respective measurement results:

[0067] a)Tr=(Tr_y_80p+Tf_z_20p) / 2–(Tr_y_20p+Tf_z_80p) / 2

[0068] b)Tf=(Tf_y_80p+Tr_z_20p) / 2–(Tf_y_20p+Tr_z_80p) / 2

[0069] c)Tphld=(Tf_y_50p+Tr_z_50p) / 2–Tf_A_50p

[0070] d)Tplhd=(Tr_y_50p+Tf_z_50p) / 2–Tr_A_50p

[0071] (9) The main control computer controls digital channel A to apply a low level to the G port of the DUT and a high level to the nG port. At the same time, it controls digital channel B to collect the voltages of the output ports Y and Z of the device under test (DUT), which are recorded as Voz_y and Voz_z. When there are multiple inputs Y / Z, each output voltage must be measured separately.

[0072] (10) The main control computer controls digital channel A to apply a high level to the A / nG port of the DUT and a positive pulse to the G port. The pulse amplitude meets the AC parameter test requirements of the DUT. At the same time, it controls digital channel B to acquire data.

[0073] a) The time it takes for the output port Y of the device under test (DUT) to reach (Voh_y-Voz_y)×0.5 is denoted as Tpzh_y; when there are multiple inputs Y / Z, the time parameter of each channel must be measured separately.

[0074] b) The time it takes for the output port Z of the device under test (DUT) to reach (Voz_z-Vol_z)×0.5 is denoted as Tpzl_z; when there are multiple input Y / Z channels, the time parameter of each channel must be measured separately.

[0075] (11) The main control computer controls digital channel A to apply a high level to the A / nG port of the DUT and a negative pulse to the G port. The pulse amplitude meets the AC parameter test requirements of the DUT. At the same time, it controls digital channel B to acquire data.

[0076] a) The time it takes for the output port Y of the device under test (DUT) to reach (Voh_y-Voz_y)×0.5 is denoted as Tphz_y; when there are multiple inputs Y / Z, the time parameter of each channel must be measured separately.

[0077] b) The time it takes for the output port Z of the device under test (DUT) to reach (Voz_z-Vol_z)×0.5 is denoted as Tplz_z; when there are multiple input Y / Z channels, the time parameter of each channel must be measured separately.

[0078] (12) The main control computer controls digital channel A to apply a low level to port A of the DUT, a high level to port nG, and a positive pulse to port G. The pulse amplitude meets the AC parameter test requirements of the DUT. At the same time, it controls digital channel B to acquire data.

[0079] a) The time it takes for the output port Y of the device under test (DUT) to reach (Voz_y-Vol_y)×0.5 is denoted as Tpzl_y; when there are multiple inputs Y / Z, the time parameter of each channel must be measured separately.

[0080] b) The time it takes for the output port Z of the device under test (DUT) to reach (Voh_z-Voz_z)×0.5 is denoted as Tpzh_z; when there are multiple inputs Y / Z, the time parameter of each channel must be measured separately.

[0081] (13) The main control computer controls digital channel A to apply a low level to port A of the DUT, a high level to port nG, and a negative pulse to port G. The pulse amplitude meets the AC parameter test requirements of the DUT. At the same time, it controls digital channel B to acquire data.

[0082] c) The time it takes for the output port Y of the device under test (DUT) to reach (Voz_y-Vol_y)×0.5 is denoted as Tplz_y; when there are multiple inputs Y / Z, the time parameter of each channel must be measured separately.

[0083] d) The time it takes for the output port Z of the device under test (DUT) to reach (Voh_z-Voz_z)×0.5 is denoted as Tphz_z; when there are multiple input Y / Z channels, the time parameter of each channel must be measured separately.

[0084] (14) The main control computer calculates Tpzh, Tphz, Tpzl, and Tplz as follows. When there are multiple differential drive channels, the time parameters of each channel must be calculated separately according to their respective measurement results:

[0085] a)Tpzh=(Tpzh_y+Tpzl_z) / 2

[0086] b)Tpzl=(Tpzl_y+Tpzh_z) / 2

[0087] c) Tphz = (Tphz_y + Tplz_z) / 2

[0088] d)Tplz=(Tplz_y+Tphz_z) / 2

[0089] The solution provided in this application, when measuring the output AC parameters of a low-voltage differential driver, connects a DC parameter measurement submodule and an AC parameter measurement submodule to the differential output port of the low-voltage differential driver. The reference voltage for the AC parameters of the output signal of the AC parameter measurement submodule is calculated using the DC parameters of the DC parameter measurement submodule's output signal. In other words, the AC parameter test conditions are specifically set using the DC parameter test results, effectively solving the problem of test consistency and stability between different channels (differential output ports) of the low-voltage differential driver.

[0090] As another example, the pulse generation module 101, the pulse parameter measurement module 103, and the AC parameter measurement submodule 108 are clock-synchronized.

[0091] Furthermore, in the solution provided in this application embodiment, the input of the compensation module 106 is the AC parameters of the pulse signal generated by the pulse generation module 101 measured by the pulse parameter measurement module 103, and the AC parameters of the differential output signal of the low-voltage differential driver 104 output by the differential output parameter measurement module 105. The compensation module 106 can calculate the compensated AC parameter test result of the low-voltage differential driver 104 output based on the measurement result of the pulse parameter measurement module 103 (the aforementioned first AC parameter) and the measurement result of the AC parameter measurement submodule 108 (the second AC parameter). For example, the compensation module 106 subtracts the measurement result of the pulse parameter measurement module 103 from the measurement result of the AC parameter measurement submodule 108 to obtain the compensated AC parameter test result of the low-voltage differential driver 104 output.

[0092] The solution provided in this application introduces a compensation module 106 when measuring the AC parameters corresponding to the low-voltage differential driver 104. The compensation module 106 compensates for the test results of the AC parameters corresponding to the low-voltage differential driver 104, effectively solving the test error caused by the 50% transition time of the input signal. Furthermore, compared to directly using the TMU or TIA instrument in an ATE instrument to test the AC parameters of the low-voltage differential driver, the test results of this application embodiment better meet the test requirements of the product manual, and the test results are more accurate.

[0093] The following description, in conjunction with the accompanying drawings, provides a more detailed explanation of an AC parameter testing method for a low-voltage differential driver provided in this application. The specific implementation of this method may include the following steps (method flow as follows): Figure 3 As shown):

[0094] Step 301: The pulse generation module generates a pulse signal and sends the pulse signal to the pulse output module and the pulse parameter measurement module.

[0095] Step 302: The pulse output module receives the pulse signal and sends the pulse signal to the pulse parameter measurement module and the low voltage differential driver.

[0096] Step 303: The pulse parameter measurement module receives the pulse signal, measures the first AC parameter of the pulse signal, and sends the first AC parameter to the compensation module.

[0097] Step 304: The low-voltage differential driver receives the pulse signal, outputs a differential signal based on the pulse signal, and sends the differential signal to the differential output parameter measurement module.

[0098] Step 305: The differential output parameter measurement module receives the differential signal and the second AC parameter for measuring the differential signal, and sends the second AC parameter to the compensation module.

[0099] Step 306: The compensation module calculates the compensated AC parameters corresponding to the low-voltage differential driver based on the first AC parameter and the second AC parameter.

[0100] Furthermore, in the solution provided in the embodiments of this application, Figure 3 In the process shown, the differential output parameter measurement module receives the differential signal and measures the second AC parameter of the differential signal, and sends the second AC parameter to the compensation module. This includes: the DC parameter measurement submodule measuring the DC output voltage of each differential output port; and the AC parameter measurement submodule calculating the corresponding AC output voltage based on the DC output voltage of each differential output port.

[0101] Specifically, in the solution provided in this application embodiment, the simplified flow of the AC parameter testing method is as follows: Figure 4 As shown, the process includes the following steps: 50% input pulse transition delay test, DC parameter test of differential output signal of low voltage differential driver, setting reference voltage for AC parameter test criteria of differential signal, and compensation calculation of AC parameter test results.

[0102] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. An AC parameter test system for low voltage differential drivers, characterized by, The application relates to a pulse signal output device, comprising: a pulse generation module, a pulse output module, a pulse parameter measurement module, a low-voltage differential driver, a differential output parameter measurement module and a compensation module; wherein, the pulse generation module is coupled with the pulse output module and is used for generating a pulse signal; the pulse output module is coupled with the pulse parameter measurement module and the low-voltage differential driver and is used for sending the pulse signal to the pulse parameter measurement module and the low-voltage differential driver; the pulse parameter measurement module is used for measuring a first alternating current parameter of the pulse signal; the low-voltage differential driver is coupled with the differential output parameter measurement module and is used for outputting a differential signal according to the pulse signal; the differential output parameter measurement module is used for measuring a second alternating current parameter of the differential signal; the compensation module is coupled with the pulse parameter measurement module and the differential output parameter measurement module and is used for calculating a compensated alternating current parameter corresponding to the low-voltage differential driver according to the first alternating current parameter and the second alternating current parameter; wherein the low-voltage differential driver comprises at least one differential output port; the differential output parameter measurement module comprises a direct current parameter measurement sub-module and an alternating current parameter measurement sub-module; wherein, the direct current parameter measurement sub-module is coupled with the low-voltage differential driver and the alternating current parameter measurement sub-module and is used for measuring a direct current output voltage of each differential output port; the alternating current parameter measurement sub-module is used for calculating a corresponding alternating current output voltage according to the direct current output voltage of each differential output port.

2. The system of claim 1, wherein, wherein, the pulse signal generated by the pulse generation module comprises a positive pulse signal from an input low-level voltage to an input high-level voltage and a negative pulse signal from an input high-level voltage to an input low-level voltage.

3. The system of claim 2, wherein, wherein, the pulse output module comprises a group of input ports, a first group of output ports and a second group of output ports; wherein the input ports and the first group of output ports constitute a first channel and the input ports and the second group of output ports constitute a second channel; the first channel is used for sending the pulse signal to the pulse parameter measurement module and the second channel is used for sending the pulse signal to the low-voltage differential driver.

4. The system of claim 3, wherein, wherein, the pulse output module sends the pulse signal to the pulse parameter measurement module through the first channel at a specified time; or sends the pulse signal to the low-voltage differential driver through the second channel.

5. The system of claim 1, wherein, wherein, each differential output port comprises a positive output port and a negative output port; the direct current output voltage comprises an output high voltage Voh_y, an output low voltage Vol_y and an output tri-state pull voltage Voz_y of the positive output port in each differential output port and an output high voltage Voh_z, an output low voltage Vol_z and an output tri-state pull voltage Voz_z of the negative output port in each differential output port.

6. The system of claim 5, wherein, wherein, The AC parameter measurement submodule calculates the rise time, fall time and transmission delay of the output signal of the forward output port according to the output high voltage Voh_y, output low voltage Vol_y and output tri-state pull voltage Voz_y of the forward output port in the each differential output port. The AC parameter measurement submodule calculates the rise time, fall time and transmission delay of the output signal of the reverse output port according to the output high voltage Voh_z, output low voltage Vol_z and output tri-state pull voltage Voz_z of the reverse output port in the each differential output port.

7. The system of claim 6, wherein, Wherein, The pulse generation module, the pulse parameter measurement module and the AC parameter measurement submodule are clock-synchronized.

8. A method of AC parameter testing of a low voltage differential driver, characterized by, Comprise: The pulse generation module generates a pulse signal and sends the pulse signal to the pulse output module and the pulse parameter measurement module; The pulse output module receives the pulse signal and sends the pulse signal to the pulse parameter measurement module and the low-voltage differential driver; The pulse parameter measurement module receives the pulse signal and measures the first AC parameter of the pulse signal, and sends the first AC parameter to the compensation module; The low-voltage differential driver receives the pulse signal, outputs a differential signal according to the pulse signal, and sends the differential signal to the differential output parameter measurement module; The differential output parameter measurement module receives the differential signal and measures the second AC parameter of the differential signal, and sends the second AC parameter to the compensation module; The compensation module calculates the compensated AC parameter corresponding to the low-voltage differential driver according to the first AC parameter and the second AC parameter; Wherein, the differential output parameter measurement module comprises a DC parameter measurement submodule and an AC parameter measurement submodule; wherein, The differential output parameter measurement module receives the differential signal and measures the second AC parameter of the differential signal, and sends the second AC parameter to the compensation module, comprising: the DC parameter measurement submodule measures the DC output voltage of each differential output port; the AC parameter measurement submodule calculates the corresponding AC output voltage according to the DC output voltage of each differential output port.

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