CN115932537A - A system and method for testing AC parameters of a low-voltage differential driver - Google Patents

Abstract

The application discloses alternating current parameter test system and method of low voltage differential driver, this system includes: the pulse generating module is coupled with the pulse output module and used for generating a pulse signal; the pulse output module is coupled with the pulse parameter measuring module and the low-voltage differential driver and used for sending the pulse signal to the pulse parameter measuring module and the low-voltage differential driver; the pulse parameter measuring module is used for measuring a first alternating current parameter of the pulse signal; the low-voltage differential driver and the differential output parameter measuring module are used for measuring a second alternating current parameter corresponding to the low-voltage differential driver; and the compensation module is coupled with the pulse parameter measurement module and the differential output parameter measurement module and used for calculating and obtaining compensated alternating current parameters corresponding to the low-voltage differential driver according to the first alternating current parameters and the second alternating current parameters. The technical problem that an alternating current parameter testing scheme in the prior art cannot meet actual requirements is solved.

Description

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

technical field

The present application relates to the technical field of integrated circuit testing, in particular to a system and method for testing AC parameters of a low-voltage differential driver.

Background technique

As a high-speed interface drive circuit, the low-voltage differential driver is used to convert single-ended CMOS signals into low-voltage differential signals to meet the needs of high-speed and high-reliability transmission. Typical low-voltage differential signals have a common-mode voltage of about 1.25V and a differential-mode voltage of about 350mV. Due to the small differential signal swing and strong anti-common-mode interference ability, it is mainly used for high-speed data transmission within a short distance between boards and boards. AC parameter is a kind of important parameter index of integrated circuit, and it is a must-test item in integrated circuit screening test. For high-speed integrated circuits, AC parameters are particularly important. The AC parameters of the low-voltage differential driver mainly include: output signal rise time Tr, output signal fall time Tf and output signal transmission delay, for example, the transmission delay Tphl of the output signal from high to low, the transmission delay Tplh of the output signal from low to high , Transmission delay Tpzl of output signal from high impedance to low, transmission delay Tpzh of output signal from high impedance to high, transmission delay Tplz of output signal from low impedance to high impedance, transmission delay Tphz of output signal from high impedance to high impedance, transmission Delay skew Tskd and inter-channel/inter-device skew Tsk, etc. The general requirements for AC parameter testing in integrated circuit test standards (or device manuals) are: for transmission delay parameters, it is required that the input signal change to 50% Vin voltage as the starting point, and the measured output signal change is (Vol+Voh) /2; for the rising (falling) time, it is required to measure the time when the output voltage rises from 20% to 80% (80% falls to 20%).

At present, in the screening test of integrated circuits, AC parameters are generally carried out using automatic test equipment (ATE, Automatic Test Equipment). When using ATE testing, you can use a dedicated TMU or TIA instrument to test AC parameters. The principle is to use the jump point of the input signal as the reference time point, and then set a reference criterion for the output voltage, and collect the output voltage from high to low. The relative time to pass through this reference voltage when it is low (or from low to high) is used as the test result. However, when testing AC parameters through ATE's TIA or TMU, the main errors come from the following two aspects:

1) The test standard (or device manual) generally requires that the input signal reaches 50% of its high voltage as the starting timing point, while ATE takes the starting point of the input signal change as the starting timing point, and the difference between the two is 50% % of the input signal transition time.

The factors that affect the transition time of the input signal mainly include two points: the first is the driving capability of the ATE signal source; the second is the influence of the parasitic parameters of the test load board circuit and the test fixture. Among them, the driving capability of the ATE signal source can be obtained by consulting the ATE technical data, while the influence of the parasitic parameters of the test load board is related to the specific hardware design. In the actual test, the transition time of the input signal provided by ATE to the circuit under test is about 1 ns-2 ns, and 50% of it is 0.5 ns-1 ns. For low-speed circuits, this error will not have a significant impact on the final test results, but for high-speed circuits such as low-voltage differential drivers, its impact cannot be ignored.

2) When using ATE to measure AC parameters, it is necessary to set a voltage value for the output signal as a criterion for the end point of time measurement. For general single-ended circuits, such as integrated circuits with 3.3V CMOS level standards, under the condition of no current load, the high voltage of the output signal is normally about 3.3V, and the deviation is very small, so you can directly use 3.3V/2 , as a criterion for measuring AC parameters.

For low-voltage differential drivers, according to the requirements in the manual, it is necessary to use 50% of the output differential voltage VOD (the differential voltage of a group of output ports of the low-voltage differential driver, also called differential mode voltage) as the measurement criterion for AC parameters. Due to the limitation of the chip manufacturing process, different circuits or different differential channels of the same circuit generally have certain differences in VOD. For example, the output VOD is considered qualified between 247mV and 454mV (typical value is about 350mV). Since the VOD given in the manual is not a relatively accurate value, it cannot be used as a criterion for measuring AC parameters in actual testing. Taking the lower limit will cause obvious errors in the measurement results, and taking the upper limit will result in failure to obtain test results because the output of some channels cannot reach the specified VOD.

Contents of the invention

The technical problem solved by this application is: Aiming at the fact that the AC parameter test scheme in the prior art cannot meet the actual needs, this application provides an AC parameter test system and method for a low-voltage differential drive. The solution provided by the embodiment of the application is used in When measuring the AC parameters corresponding to the low-voltage differential driver, a compensation module is introduced. The compensation module is used to compensate the AC parameter test results corresponding to the low-voltage differential driver, which effectively solves the test error caused by the 50% jump time of the input signal. In addition, compared with directly using the TMU and TIA in the ATE instrument to test the AC parameters of the low-voltage differential driver, the test results of the embodiment of the present application are more in line with the test requirements of the product manual, and the test results are more accurate.

In the first aspect, an embodiment of the present application provides an AC parameter testing system for a low-voltage differential driver. The 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 compensation module; where,

The pulse generation module is coupled with the pulse output module and is used to generate a pulse signal;

The pulse output module is coupled with 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;

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

The low-voltage differential driver and the differential output parameter measurement module are used to output a differential signal according to the pulse signal;

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

The compensation module, coupled with the pulse parameter measurement module and the differential output parameter measurement module, is used to calculate and obtain the compensation corresponding to the low voltage differential driver according to the first AC parameter and the second AC parameter After the exchange parameters.

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 .

Optionally, wherein 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 form a first channel, the The input port and the second group 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 the low voltage differential driver.

Optionally, wherein, the pulse output module sends the pulse signal to the pulse parameter measurement module through the first channel at a specified moment; or sends the pulse signal to the pulse parameter measurement module through the second channel Low Voltage Differential Driver.

Optionally, wherein, 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, and The low-voltage differential driver is coupled to the AC parameter measurement sub-module for measuring the DC output voltage of each differential output port; the AC parameter measurement sub-module is used for measuring the DC output voltage of each differential output port according to the The voltage calculation corresponds to the AC output voltage.

Optionally, wherein each differential output port includes a forward output port and a reverse output port; the DC output voltage includes output high voltage Voh_y, output low voltage Vol_y, output low voltage Vol_y, Outputting a tri-state pull-bias voltage Voz_y; and an output high voltage Voh_z, an output low voltage Vol_z, and an output tri-state pull-bias voltage Voz_z of the reverse output port of each differential output port.

Optionally, the AC parameter measurement submodule calculates the output signal of the forward output port according to the output high voltage Voh_y, the output low voltage Vol_y, and the output tri-state pull-bias voltage Voz_y of the forward output port in each differential output port. Rise time, fall time, and transmission delay; and calculate the corresponding reverse output port according to the output high voltage Voh_z, output low voltage Vol_z, and output tri-state pull-bias voltage Voz_z of the reverse output port in each differential output port The rise time, fall time, and propagation delay of the output signal.

Optionally, the clocks of the pulse generation module, the pulse parameter measurement module and the AC parameter measurement sub-module are synchronized.

In the second aspect, the embodiment of the present application provides a method for testing AC parameters of a low-voltage differential driver, the method comprising:

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, measures a first AC parameter of the pulse signal, and sends the first AC parameter to a 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 a differential output parameter measurement module;

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;

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.

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 converts the second The AC parameters are sent to the compensation module, including: the DC parameter measurement sub-module measures the DC output voltage of each differential output port; the AC parameter measurement sub-module calculates the corresponding AC voltage according to the DC output voltage of each differential output port. The output voltage.

Compared with the prior art, the solution provided by the embodiment of the present application has at least the following beneficial effects:

1. In the solution provided by the embodiment of the present application, when measuring the AC parameters corresponding to the low-voltage differential driver, a compensation module is introduced. The compensation module is used to compensate the AC parameter test results corresponding to the low-voltage differential driver, which effectively solves the test error caused by the 50% jump time of the input signal. In addition, compared with directly using the TMU and TIA in the ATE instrument to test the AC parameters of the low-voltage differential driver, the test results of the embodiment of the present application are more in line with the test requirements of the product manual, and the test results are more accurate.

2. In the solution provided by the embodiment of the present application, when measuring the output AC parameters of the low-voltage differential driver, the DC parameter measurement sub-module and the AC parameter measurement sub-module are connected to the differential output port of the low-voltage differential driver. Measuring the DC parameter of the output signal of the sub-module to calculate the reference voltage of the AC parameter for measuring the AC parameter of the output signal of the sub-module. That is, the test results of the DC parameters are used to set the test conditions of the AC parameters in a targeted manner, which effectively solves the problem of test consistency and stability between different channels (differential output ports) of the low-voltage differential drive.

Description of drawings

FIG. 1 is a schematic diagram of an AC parameter testing system for a low-voltage differential driver provided in an embodiment of the present application;

Fig. 2 has shown a kind of circuit schematic diagram that adopts TMU or TIA instrument to measure AC parameter provided by the embodiment of the present application;

FIG. 3 is a schematic flowchart of a method for testing AC parameters of a low-voltage differential driver provided in an embodiment of the present application;

FIG. 4 is a brief flow chart of a method for testing AC parameters of a low-voltage differential driver provided by an embodiment of the present application.

Detailed ways

In the solutions provided by the embodiments of the present application, the described embodiments are only some of the embodiments of the present application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

In order to better understand the above technical solutions, the technical solutions of the present application will be described in detail below through the accompanying drawings and specific examples. It should be understood that the embodiments of the present application and the specific features in the examples are detailed descriptions of the technical solutions of the present application, and It is not a limitation to the technical solutions of the present application, and the embodiments of the present application and the technical features in the embodiments can be combined without conflict.

FIG. 1 shows a schematic diagram of an AC parameter testing system for a low-voltage differential driver provided by an embodiment of the present application.

As an example, in FIG. 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; wherein, The pulse generation module 101 is coupled with the pulse output module 102 for generating pulse signals; the pulse output module 102 is coupled with the pulse parameter measurement module 103 and the low voltage differential driver 104 for sending the pulse signal to the pulse parameter measurement module 103 and Low-voltage differential driver 104; pulse parameter measurement module 103, used to measure the first AC parameter of the pulse signal; low-voltage differential driver 104, and differential output parameter measurement module 105, used to output differential signals according to the pulse signal; differential output parameter measurement The module 105 is used to measure the second AC parameter of the differential signal; the compensation module 106 is coupled with the pulse parameter measurement module 103 and the differential output parameter measurement module 105, and is used to calculate the low voltage differential according to the first AC parameter and the second AC parameter. The compensated AC parameters corresponding to the driver.

As another example, the pulse generation module 101 is used to generate an input pulse signal for testing the AC parameters of the low voltage differential driver 104 (or referred to as the circuit under test). The voltage amplitude and frequency (or pulse width) of the pulse signal can be controlled by, for example, software programming; level voltage to the negative pulse signal of the input low level voltage. In addition, the 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 the output enable port G/nG of the low voltage differential driver 104 .

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 (the pulse parameter measurement module 103 or the 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, for example, two output ports are output port A and output port B; wherein, the input port and output port A constitute channel C1, and the input port and output port B A channel C2 is formed; the channel C1 is used to send the pulse signal to the pulse parameter measurement module 103 , and the 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

As another example, the pulse output module 102 sends the pulse signal to the pulse parameter measurement module 103 through the channel C1 at a specified moment; or sends the pulse signal to the low voltage differential driver 104 through the channel C2. That is to say, two groups of channels can be selected under software control, and only one group of output channels can be selected at the same time.

In addition, the solution provided in the embodiment of the present application is to compensate the AC parameter of the output signal of the low-voltage differential driver 104 . In the test system shown in FIG. 1 , a pulse parameter measurement module 103 is also provided; wherein, the input of the pulse parameter measurement module 103 is the pulse signal generated by the pulse generation module 101 , and the output is the AC parameter 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 group of test pulse detection input ports, and the TMU instrument or TIA instrument of ATE equipment can be used to test the rise time Tr and fall time Tf of the input pulse signal; wherein, the Tr/Tf of the input pulse signal The test reference voltage can be set by software; the test time resolution can be set by software. The test result (the AC parameter of the pulse signal) of the pulse parameter measurement module 103 is given to the follow-up compensation module 106

Further, as an example, the low-voltage differential driver 104 includes at least one differential output port; for example, the low-voltage differential driver 104 includes one or more single-ended input ports A, output enable ports G/nG, one or more The 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 generating module 101 , the number of channels for transmitting the pulse signal can cover the input port A and the output enable port G/nG of the low voltage differential driver 104 .

In addition, in order to ensure the test consistency and stability between different channels (differential output ports) of the low voltage differential driver 104 . As an example, the differential output parameter measurement module 105 includes a DC parameter measurement submodule 107 and an AC parameter measurement submodule 108; wherein, the DC parameter measurement submodule 107 is coupled with the low voltage differential driver 104 and the AC parameter measurement submodule 108 for Measure the DC output voltage at each differential output port. As an example, the DC output voltage includes the output high voltage Voh_y, the output low voltage Vol_y, and the output tri-state pull bias voltage Voz_y of the forward output port in each differential output port; and the output high voltage of the reverse output port in each differential output port Voh_z, the output low voltage Vol_z, and the output tri-state pull-bias voltage Voz_z.

The AC parameter measurement sub-module 108 is configured to calculate the corresponding AC output voltage according to the DC output voltage of each differential output port. As an example, the AC parameter measurement sub-module 108 calculates the rise time, fall time, Time and transmission delay; and calculate the rise time of the output signal corresponding to the reverse output port according to the output high voltage Voh_z, output low voltage Vol_z and output tri-state pull bias voltage Voz_z of the reverse output port in each differential output port, Fall time and transmission delay. For example, use a TMU or TIA meter to test the AC parameters of the pulse signal, including rise time Tr, fall time Tf, transmission delay Tphl/Tplh/Tpzl/Tpzh/Tplz/Tphz; the AC parameter test reference voltage is determined by the DC parameter measurement sub-module 107 The measurement results of the AC parameters are calculated 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 sent to the AC parameter measurement result compensation module 106.

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

In the above-mentioned system shown in FIG. 1 , the pulse parameter measurement module 103 and the AC parameter measurement sub-module can use the TMU or TIA instrument in the ATE instrument to measure the AC parameter. The following briefly introduces the process of using the TMU or TIA instrument in the ATE instrument to measure the AC parameters in the embodiment of the present application.

FIG. 2 shows a schematic circuit diagram of a TMU or TIA instrument for measuring AC parameters provided by an embodiment of the present application.

As an example, in Figure 2, the circuit mainly includes an ATE tester and a Loadboard test board. The ATE testing machine mainly includes a main control computer, supporting instruments, DC source instruments and digital channel instruments. Among them, the main control computer is the core unit for instrument control, test signal graphic generation and data summary analysis; the supporting instrument mainly realizes the power supply and switch control of the relay matrix; the DC source instrument supplies power for the device under test (DUT); the digital channel is mainly divided into Three groups, identified by A, B, and C in the figure. Group A is a test input signal (relative to the device under test DUT), which is used to provide a test input pulse for the device under test (such as the low-voltage differential driver 104 shown in Figure 1 above), including A, G and nG ports; Group B is The test output signal is used to collect the AC parameters of the device under test, including the Y and Z groups of ports; the C group is also the test output signal, used to collect the AC parameters of the digital channel A output signal, including the A, G and nG ports.

The Loadboard test board mainly includes the device under test (DUT) and the matrix array (Relay). In addition, the differential output terminals Y/Z of the device under test also need to be connected with necessary resistors, capacitive loads and a Vos pull-bias power supply (not shown in Figure 2).

The specific workflow of the circuit shown in Figure 2 is as follows:

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

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

(3) The main control computer sends instructions to the supporting instrument to control the supporting instrument to switch the signal output of the Relay to the DUT.

(4), the main control computer controls the digital channel A, applies a high level to the G port of the DUT, applies a low level to the nG port, and applies a high level to the A port, and simultaneously controls the digital channel B to collect the DUT output port Y, The voltage of Z is recorded as Voh_y and Vol_z; when there are multiple inputs Y/Z, each output voltage must be measured separately.

(5), the main control computer controls the digital channel A, applies a high level to the G port of the DUT, applies a low level to the nG port, and applies a low level to the A port, and simultaneously controls the digital channel B to collect the DUT output port Y, The voltage of Z is recorded as Vol_y and Voh_z; when there are multiple inputs Y/Z, each output voltage must be measured separately.

(6) The main control computer controls the digital channel A, applies high level to the G port of the DUT, applies a low level to the nG port, and applies a positive pulse to the A port. The pulse amplitude meets the DUT AC parameter test requirements, and at the same time controls the digital channel. B collection.

a) The time when the DUT output port Y of the DUT reaches Vol_y+(Voh_y-Vol_y)×0.2, Vol_y+(Voh_y-Vol_y)×0.5, Vol_y+(Voh_y-Vol_y)×0.8 respectively, recorded as Tr_y_20p, Tr_y_50p, Tr_y_80p; When multi-channel input Y/Z, each time parameter should be measured separately.

b) The time when the DUT output port Z of the device under test reaches Vol_z+(Voh_z-Vol_z)×0.8, Vol_z+(Voh_z-Vol_z)×0.5, Vol_z+(Voh_z-Vol_z)×0.2 respectively, recorded as Tf_z_80p, Tf_z_50p, Tf_z_20p; When multi-channel input Y/Z, each time parameter should be measured separately.

(7) The main control computer controls the digital channel A, applies a high level to the G port of the DUT, applies a low level to the nG port, and applies a negative pulse to the A port. The pulse amplitude meets the DUT AC parameter test requirements, and at the same time controls the digital channel. B collection.

1) The time when the DUT output port Y of the device under test reaches Vol_y+(Voh_y-Vol_y)×0.8, Vol_y+(Voh_y-Vol_y)×0.5, Vol_y+(Voh_y-Vol_y)×0.2 respectively, recorded as Tf_y_80p, Tf_y_50p, Tf_y_20p; When multi-channel input Y/Z, each time parameter should be measured separately.

2) The time when the DUT output port Z of the device under test reaches Vol_z+(Voh_z-Vol_z)×0.2, Vol_z+(Voh_z-Vol_z)×0.5, Vol_z+(Voh_z-Vol_z)×0.8 respectively, recorded as Tr_z_20p, Tr_z_50p, Tr_z_80p; When multi-channel input Y/Z, each time parameter should be measured separately.

(8), the main control computer calculates Tr, Tf, Tphld, Tplhd according to the following method, when there are multiple differential drive channels, the time parameters of each channel must be calculated separately according to their respective measurement results:

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

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

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

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

(9) The main control computer controls the digital channel A, applies a low level to the G port of the DUT, and applies a high level to the nG port, and at the same time controls the digital channel B to collect the voltages of the DUT output ports Y and Z of the device under test, which is recorded as Voz_y And Voz_z; when there are multiple inputs Y/Z, each output voltage should be measured separately.

(10), the main control computer controls the digital channel A, applies a high level to the A/nG port of the DUT, and applies a forward pulse to the G port. The pulse amplitude meets the DUT AC parameter test requirements, and at the same time controls the digital channel B to collect:

a) The time when the DUT output port Y of the device under test reaches (Voh_y-Voz_y)×0.5, which is recorded as Tpzh_y; when there are multiple inputs Y/Z, each time parameter must be measured separately;

b) The time when the DUT output port Z of the device under test reaches (Voz_z-Vol_z)×0.5, which is recorded as Tpzl_z; when there are multiple inputs Y/Z, each time parameter must be measured separately;

(11), the main control computer controls the digital channel A, applies a high level to the A/nG port of the DUT, and applies a negative pulse to the G port. The pulse amplitude meets the DUT AC parameter test requirements, and at the same time controls the digital channel B to collect:

a) The time when the DUT output port Y of the device under test reaches (Voh_y-Voz_y)×0.5, which is recorded as Tphz_y; when there are multiple inputs Y/Z, each time parameter must be measured separately;

b) The time when the DUT output port Z of the device under test reaches (Voz_z-Vol_z)×0.5, which is recorded as Tplz_z; when there are multiple inputs Y/Z, each time parameter must be measured separately;

(12) The main control computer controls the digital channel A, applies low level to the A port of the DUT, applies high level to the nG port, and applies a positive pulse to the G port. The pulse amplitude meets the DUT AC parameter test requirements, and at the same time controls the digital channel. B collection:

a) The time when the DUT output port Y of the device under test reaches (Voz_y-Vol_y)×0.5, which is recorded as Tpzl_y; when there are multiple inputs Y/Z, each time parameter must be measured separately;

b) The time when the DUT output port Z of the device under test reaches (Voh_z-Voz_z)×0.5, which is recorded as Tpzh_z; when there are multiple inputs Y/Z, each time parameter must be measured separately;

(13) The main control computer controls the digital channel A, applies a low level to the A port of the DUT, applies a high level to the nG port, and applies a negative pulse to the G port. The pulse amplitude meets the DUT AC parameter test requirements, and at the same time controls the digital channel. B collection:

c) The time when the DUT output port Y of the device under test reaches (Voz_y-Vol_y)×0.5, which is recorded as Tplz_y; when there are multiple inputs Y/Z, each time parameter must be measured separately;

d) The time when the DUT output port Z of the device under test reaches (Voh_z-Voz_z)×0.5, which is recorded as Tphz_z; when there are multiple inputs Y/Z, each time parameter must be measured separately;

(14), the main control computer calculates Tpzh, Tphz, Tpzl, Tplz according to the following method, when there are multiple differential drive channels, each time parameter should be calculated separately according to the respective measurement results:

a)Tpzh=(Tpzh_y+Tpzl_z)/2

b) Tpzl=(Tpzl_y+Tpzh_z)/2

c) Tphz=(Tphz_y+Tplz_z)/2

d)Tplz=(Tplz_y+Tphz_z)/2

In the solution provided by the embodiment of the present application, when measuring the output AC parameters of the low-voltage differential driver, the DC parameter measurement sub-module and the AC parameter measurement sub-module are connected to the differential output port of the low-voltage differential driver, and the DC parameter measurement sub-module The DC parameter of the output signal of the module is used to calculate the AC parameter and measure the reference voltage of the AC parameter of the output signal of the sub-module. That is, the test results of the DC parameters are used to set the test conditions of the AC parameters in a targeted manner, which effectively solves the problem of test consistency and stability between different channels (differential output ports) of the low-voltage differential drive.

As another example, the clocks of the pulse generation module 101 , the pulse parameter measurement module 103 and the AC parameter measurement sub-module 108 are synchronized.

Further, in the solution provided by the embodiment of the present application, the input of the compensation module 106 is the AC parameter of the pulse signal generated by the pulse generation module 101 measured by the pulse parameter measurement module 103, and the low voltage output by the differential output parameter measurement module 105 The AC parameter of the output signal of the differential output port of the differential driver 104 . The compensation module 106 can calculate the compensated AC output from the low-voltage differential driver 104 according to the measurement result of the pulse parameter measurement module 103 (the above-mentioned first AC parameter) and the measurement result of the AC parameter measurement sub-module 108 (the second AC parameter). Parameter test results. 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 sub-module 108 to obtain the compensated AC parameter test result output by the low voltage differential driver 104 .

The solution provided by the embodiment of the present application introduces the compensation module 106 when measuring the AC parameters corresponding to the low-voltage differential driver 104 . The AC parameter test results corresponding to the low voltage differential driver 104 are compensated by the compensation module 106, which effectively solves the test error caused by the 50% transition time of the input signal. In addition, compared with directly using the TMU or TIA instrument in the ATE instrument to test the AC parameters of the low-voltage differential driver, the test results of the embodiment of the present application are more in line with the test requirements of the product manual, and the test results are more accurate.

A method for testing AC parameters of a low-voltage differential driver provided in the embodiment of the present application will be further described in detail below in conjunction with the accompanying drawings. The specific implementation of the method may include the following steps (the method flow is shown in Figure 3):

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.

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.

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.

Step 304, 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.

Step 305, the differential output parameter measurement module receives the differential signal, measures a second AC parameter of the differential signal, and sends the second AC parameter to the compensation module.

Step 306 , the compensation module calculates the compensated AC parameters corresponding to the low voltage differential driver according to the first AC parameters and the second AC parameters.

Further, in the solution provided by the embodiment of the present application, in the process shown in Figure 3, 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, Including: the DC parameter measurement sub-module measures the DC output voltage of each differential output port; the AC parameter measurement sub-module calculates the corresponding AC output voltage according to the DC output voltage of each differential output port.

Specifically, in the solution provided by the embodiment of the present application, the brief flow of the AC parameter test method is shown in Figure 4, including the following several processes: input pulse 50% transition delay test, low voltage differential driver differential output signal DC parameter test , Set differential signal AC parameter test criterion reference voltage, AC parameter test result compensation calculation.

Obviously, those skilled in the art can make various changes and modifications to the application without departing from the spirit and scope of the application. In this way, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.

Claims (10)

1. An AC parameter testing system of a low-voltage differential driver, 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 to generate a pulse signal; The pulse output module is coupled with 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; The pulse parameter measurement module is used to measure the first AC parameter of the pulse signal; The low-voltage differential driver and the differential output parameter measurement module are used to output a differential signal according to the pulse signal; The differential output parameter measurement module is used to measure the second AC parameter of the differential signal; The compensation module, coupled with the pulse parameter measurement module and the differential output parameter measurement module, is used to calculate and obtain the compensation corresponding to the low voltage differential driver according to the first AC parameter and the second AC parameter After the exchange parameters. 2. The system according to claim 1, wherein the pulse signal generated by the pulse generation module includes a forward pulse signal from an input low-level voltage to an input high-level voltage and an input high-level voltage Negative-going pulse signal to input low-level voltage. 3. The system according to claim 2, wherein 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 port and the second set of output ports A group of output ports constitutes a first channel, and the input port and the second group 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 The two channels are used to send the pulse signal to the low voltage differential driver. 4. The system according to claim 3, wherein, the pulse output module sends the pulse signal to the pulse parameter measurement module through the first channel at a specified moment; or through the second channel The second channel sends the pulse signal to the low voltage differential driver. 5. The system according to any one of claims 1-4, wherein 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 with 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 sub-module is used to calculate the corresponding AC output voltage according to the DC output voltage of each differential output port. 6. The system according to claim 5, wherein each differential output port includes a forward output port and a reverse output port; The DC output voltage includes the output high voltage Voh_y, the output low voltage Vol_y, and the output tri-state pull bias voltage Voz_y of the positive output port in each differential output port; and the output high voltage Voh_z of the reverse output port in each differential output port , output low voltage Vol_z, and output tri-state pull bias voltage Voz_z. 7. The system according to claim 6, wherein the AC parameter measurement sub-module is based on the output high voltage Voh_y, the output low voltage Vol_y and the output tri-state of the positive output port in each differential output port The pull bias voltage Voz_y calculates the rise time, fall time and transmission delay of the output signal of the positive output port; and Calculate the rise time, fall time and transmission time of the output signal corresponding to the reverse output port according to the output high voltage Voh_z, output low voltage Vol_z and output tri-state pull bias voltage Voz_z of the reverse output port in each differential output port delay. 8. The system according to claim 7, wherein the clocks of the pulse generation module, the pulse parameter measurement module and the AC parameter measurement sub-module are synchronized. 9. A method for testing AC parameters of a low-voltage differential driver, comprising: 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, measures a first AC parameter of the pulse signal, and sends the first AC parameter to a 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 a differential output parameter measurement module; 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; 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. 10. The method according to claim 9, wherein 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 the differential signal and measures the second AC parameter of the differential signal, and sends the second AC parameter to the compensation module, including: the DC parameter measurement sub-module measures the DC output voltage of each differential output port ; The AC parameter measurement sub-module calculates the corresponding AC output voltage according to the DC output voltage of each differential output port.

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