CN115932537A - Alternating current parameter testing system and method of 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

Alternating current parameter testing system and method of low-voltage differential driver

Technical Field

The present disclosure relates to the field of integrated circuit testing technologies, and in particular, to an ac parameter testing system and method for a low voltage differential driver.

Background

The low-voltage differential driver is used as a high-speed interface driving circuit and is used for converting a single-ended CMOS signal into a low-voltage differential signal so as to meet the requirement of high-speed and high-reliability transmission. The common mode voltage of a typical low voltage differential signal is about 1.25V and the differential mode voltage is about 350mV. Because the differential signal has small swing and strong common mode interference resistance, the differential signal is mainly used for high-speed data transmission in short distance between boards. The alternating current parameters are important parameter indexes of the integrated circuit and are necessary test items in the screening test of the integrated circuit. For high speed integrated circuits, ac parameter specifications are particularly important. The ac parameters of the low voltage differential driver mainly include: the rise time Tr of the output signal, the fall time Tf of the output signal, and the transmission delay of the output signal, for example, the transmission delay tpll from high to low of the output signal, the transmission delay Tplh from low to high of the output signal, the transmission delay Tpzl from high to low of the output signal, the transmission delay Tplh from high to high of the output signal, the transmission delay Tplz from low to high of the output signal, the transmission delay offset Tskd and the inter-channel/device offset Tsk. The general requirements for ac parametric testing in integrated circuit test standards (or device manuals) are: for the transmission delay-like parameter, it is required to measure until the output signal change is (Vol + Voh)/2, with the input signal change to 50%; for the rise (fall) time, it is required to measure the time for the output voltage to rise from 20% to 80% (80% to 20%).

Currently, in the screening Test of the integrated circuit, the alternating current parameter is generally performed by using Automatic Test Equipment (ATE). When ATE test is used, a special TMU or TIA instrument can be used for testing alternating current parameters, the principle is that a jump point of an input signal is used as a reference time point, a reference criterion of an output voltage is set, and the relative time of the output voltage passing through the reference voltage when the output voltage changes from high to low (or from low to high) is collected and used as a test result. However, when testing the AC parameters through TIA or TMU of ATE, the main errors are derived from the following two aspects:

1) In the test standard (or device manual), it is generally required that 50% of the input signal reaching its high voltage is used as the start timing point, and ATE is used as the start timing point of the input signal variation, which is different from the input signal transition time by 50%.

The factors influencing the transition time of the input signal mainly include two points: the first is the driving capability of the ATE signal source; and secondly, testing the influence of parasitic parameters of the load board circuit and the test fixture. The ATE signal source driving capability can be obtained by looking up ATE technical data, and the influence of the parasitic parameters of the test load board is related to the specific hardware design. In actual testing, the transition time of the input signal provided by the ATE to the circuit under test is actually measured to be about 1ns-2ns, 50% of which is 0.5ns-1ns. For low speed circuits this error does not have a significant effect on the final test results, but for high speed circuits such as low voltage differential drivers this effect cannot be neglected.

2) When the ATE is used for measuring the alternating current parameters, a voltage value needs to be set for an output signal to be used as a criterion of a time measurement end point. For a common single-ended circuit, such as an integrated circuit of a 3.3V CMOS level standard, under the condition of not applying a current load, the high voltage of an output signal is normally about 3.3V, and the deviation is extremely small, so that 3.3V/2 can be directly used as a criterion for measuring an alternating current parameter.

For low voltage differential drives, according to the requirements in the manual, 50% of the output differential voltage VOD (the differential voltage of a set of output ports of the low voltage differential drive, also called differential mode voltage) needs to be used as the measurement criterion for the ac parameter. The VOD of different circuits or different differential channels of the same circuit generally has a certain difference due to the chip manufacturing process. For example, the output VOD is qualified between 247mV and 454mV (typical value is about 350 mV). Since 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 significant errors in the measurement results, and taking the upper limit will cause the failure of obtaining the test results because the partial channel output cannot reach the specified VOD.

Disclosure of Invention

The technical problem that this application was solved is: aiming at the problem that an alternating current parameter testing scheme in the prior art cannot meet actual requirements, the application provides an alternating current parameter testing system and method of a low-voltage differential driver. The alternating current parameter test result corresponding to the low-voltage differential driver is compensated through the compensation module, and the test error caused by 50% of jump time of an input signal is effectively solved. In addition, compared with the method that the alternating current parameters of the low-voltage differential driver are tested by directly using the TMU and the TIA in the ATE instrument, the test result of the embodiment of the application better meets the test requirement of a product manual, and the test result is more accurate.

In a first aspect, an embodiment of the present application provides an ac parametric test system for a low-voltage differential driver, where the system includes: the pulse generator comprises a pulse generating module, a pulse output module, a pulse parameter measuring module, a low-voltage differential driver, a differential output parameter measuring module and a compensating module; wherein,

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 is 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 outputting differential signals according to the pulse signals;

the differential output parameter measuring 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 configured to calculate, according to the first alternating current parameter and the second alternating current parameter, a compensated alternating current parameter corresponding to the low-voltage differential driver.

Optionally, the pulse signals generated by the pulse generating module include a positive pulse signal inputting a low-level voltage to a high-level voltage and a negative pulse signal inputting a high-level voltage to a 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; the input port and the first group of output ports form a first channel, and the input port and the second group of output ports form a second channel; the first channel is used for sending the pulse signal to the pulse parameter measuring module, and the second channel is used for sending the pulse signal to the low-voltage differential driver.

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

Optionally, the low voltage differential driver includes at least one differential output port; the differential output parameter measuring module comprises a direct current parameter measuring submodule and an alternating current parameter measuring submodule; the direct-current parameter measuring submodule is coupled with the low-voltage differential driver and the alternating-current parameter measuring submodule and is used for measuring direct-current output voltage of each path of differential output port; and the alternating current parameter measuring submodule is used for calculating corresponding alternating current output voltage according to the direct current output voltage of each path of differential output port.

Optionally, wherein each of the differential output ports includes a forward output port and a reverse output port; the direct current output voltage comprises an output high voltage Voh _ y, an output low voltage Vol _ y and an output three-state pull bias voltage Voz _ y of a forward output port in each path of differential output port; and the output high voltage Voh _ z, the output low voltage Vol _ z and the output three-state pull bias voltage Voz _ z of the reverse output port in each path of differential output port.

Optionally, the alternating current parameter measurement sub-module calculates a rising time, a falling time, and a transmission delay of an output signal of the forward output port according to the output high voltage Voh _ y, the output low voltage Vol _ y, and the output three-state pull bias voltage Voz _ y of the forward output port in each path of differential output port; and calculating the rise time, the fall time and the transmission time delay of the output signal corresponding to the reverse output port according to the output high voltage Voh _ z, the output low voltage Vol _ z and the output three-state pull bias voltage Voz _ z of the reverse output port in each path of differential output port.

Optionally, wherein the pulse generation module, the pulse parameter measurement module, and the ac parameter measurement submodule are clock-synchronized.

In a second aspect, an embodiment of the present application provides an ac parametric test method for a low-voltage differential driver, where the method includes:

the pulse generating module generates a pulse signal and sends the pulse signal to the pulse output module and the pulse parameter measuring module;

the pulse output module receives the pulse signal and sends the pulse signal to a pulse parameter measuring module and a low-voltage differential driver;

the pulse parameter measuring module receives the pulse signal, measures a first alternating current parameter of the pulse signal and sends the first alternating current 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 measuring module;

the differential output parameter measuring module receives the differential signal and measures a second alternating current parameter of the differential signal, and sends the second alternating current parameter to the compensation module;

and the compensation module calculates to obtain compensated alternating current parameters corresponding to the low-voltage differential driver according to the first alternating current parameters and the second alternating current parameters.

Optionally, the differential output parameter measuring module includes a direct current parameter measuring submodule and an alternating current parameter measuring submodule; wherein, the differential output parameter measurement module receives the differential signal and measures the second alternating current parameter of the differential signal, and sends the second alternating current parameter to the compensation module, including: the direct current parameter measuring submodule measures direct current output voltage of each path of differential output port; and the alternating current parameter measuring submodule calculates corresponding alternating current output voltage according to the direct current output voltage of each path of differential output port.

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

1. according to the scheme provided by the embodiment of the application, the compensation module is introduced when the alternating current parameters corresponding to the low-voltage differential driver are measured. The alternating current parameter test result corresponding to the low-voltage differential driver is compensated through the compensation module, and the test error caused by 50% of jump time of the input signal is effectively solved. In addition, compared with the method that the alternating current parameters of the low-voltage differential driver are tested by directly using the TMU and the TIA in the ATE instrument, the test result of the embodiment of the application better meets the test requirement of a product manual, and the test result is more accurate.

2. According to the scheme provided by the embodiment of the application, when the output alternating current parameters of the low-voltage differential driver are measured, the direct current parameter measuring submodule and the alternating current parameter measuring submodule are connected to the differential output port of the low-voltage differential driver, and the reference voltage of the alternating current parameters of the output signals of the alternating current parameter measuring submodule is calculated through the direct current parameters of the output signals of the direct current parameter measuring submodule. The test result of the direct current parameter is adopted to carry out targeted setting on the test condition of the alternating current parameter, and the problems of test consistency and stability among different channels (differential output ports) of the low-voltage differential driver are effectively solved.

Drawings

Fig. 1 is a schematic diagram of an ac parametric test system for a low voltage differential driver according to an embodiment of the present disclosure;

FIG. 2 shows a schematic circuit diagram for measuring AC parameters using a TMU or TIA meter according to an embodiment of the present application;

fig. 3 is a schematic flowchart of an ac parametric testing method for a low voltage differential driver according to an embodiment of the present disclosure;

fig. 4 is a schematic flowchart of an ac parametric testing method for a low voltage differential driver according to an embodiment of the present disclosure.

Detailed Description

In the solutions provided in the embodiments of the present application, the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In order to better understand the technical solutions, the technical solutions of the present application are described in detail below with reference to the drawings and specific embodiments, and it should be understood that the specific features in the embodiments and examples of the present application are detailed descriptions of the technical solutions of the present application, and are not limitations of the technical solutions of the present application, and the technical features in the embodiments and examples of the present application may be combined with each other without conflict.

Fig. 1 illustrates a schematic diagram of an ac parametric test system for a low voltage differential driver according to an embodiment of the present application.

By way of example, in fig. 1, the ac parametric test system includes: the pulse generator comprises a pulse generating module 101, a pulse output module 102, a pulse parameter measuring module 103, a low-voltage differential driver 104, a differential output parameter measuring module 105 and a compensating module 106; the pulse generating module 101 is coupled with the pulse output module 102 and is used for generating a pulse signal; the pulse output module 102 is coupled with the pulse parameter measuring module 103 and the low voltage differential driver 104, and is configured to send a pulse signal to the pulse parameter measuring module 103 and the low voltage differential driver 104; the pulse parameter measuring module 103 is used for measuring a first alternating current parameter of the pulse signal; a low voltage differential driver 104 and a differential output parameter measuring module 105, configured to output a differential signal according to the pulse signal; a differential output parameter measuring module 105, configured to measure a second alternating current parameter of the differential signal; and the compensation module 106 is coupled with the pulse parameter measurement module 103 and the differential output parameter measurement module 105, and configured to calculate, according to the first alternating current parameter and the second alternating current parameter, a compensated alternating current parameter corresponding to the low-voltage differential driver.

For example, the pulse generating module 101 is used to generate an input pulse signal for an ac parametric test of the low voltage differential driver 104 (or referred to as a circuit under test). The voltage amplitude and frequency (or pulse width) of the pulse signal can be controlled by, for example, software programming; the pulse signal generated by the pulse generating module comprises a positive pulse signal for inputting a low-level voltage to a high-level voltage and a negative pulse signal for inputting a high-level voltage to a 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 parameter 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.

Also by way of example, the pulse output module 102 is configured to select a transmission path for the pulse signal generated by the pulse generating module 101, for example, send the pulse signal to the pulse parameter measuring module 103, or send the pulse signal to the low voltage differential driver 104. That is, the pulse output module 102 may send the pulse signal to two different modules or circuits (the pulse parameter measuring module 103 or the low voltage differential driver 104). Therefore, the pulse output module 102 includes at least one input port and two output ports. For example, the pulse output module 102 at least includes a set of input ports and two sets of output ports, for example, two output ports are output port a and output port B; the input port and the output port A form a channel C1, and the input port and the output port B form a 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

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

In addition, the scheme provided by 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 further provided; the input of the pulse parameter measuring module 103 is a pulse signal generated by the pulse generating module 101, and the output is an ac parameter corresponding to the pulse signal. For example, the pulse parameter measuring module 103 is used to measure the rise time of the pulse generated by the pulse generating module 101. Specifically, the pulse parameter measurement module 103 has a set of test pulse detection input ports, and may use a TMU meter or a TIA meter of the ATE device to test the rise time Tr and the fall time Tf of the input pulse signal; wherein, the test reference voltage of Tr/Tf of the input pulse signal can be set by software; the test time resolution may be set by software. The test result (the ac parameter of the pulse signal) of the pulse parameter measuring module 103 is sent to the subsequent compensation module 106

Further, by way of example, the low voltage differential driver 104 includes at least one differential output port; for example, the low voltage differential driver 104 includes 1 or more single-ended input ports a, output enable ports G/nG, and 1 or more differential output ports Y (forward direction) and Z (reverse direction), i.e., each differential output port includes a forward direction output port and a reverse direction 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. By way of example, the differential output parameter measurement module 105 includes a dc parameter measurement sub-module 107 and an ac parameter measurement sub-module 108; the dc parameter measurement submodule 107 is coupled to the low voltage differential driver 104 and the ac parameter measurement submodule 108, and is configured to measure a dc output voltage of each path of differential output port. By way of example, the direct-current output voltage comprises an output high voltage Voh _ y, an output low voltage Vol _ y and an output three-state pull bias voltage Voz _ y of a forward output port in each path of differential output port; and the output high voltage Voh _ z, the output low voltage Vol _ z and the output three-state pull bias voltage Voz _ z of the reverse output port in each path of differential output port.

And the alternating current parameter measuring submodule 108 is used for calculating corresponding alternating current output voltage according to the direct current output voltage of each path of differential output port. For example, the ac parameter measurement sub-module 108 calculates the rise time, the fall time, and the transmission delay of 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; and calculating the rising time, falling time and transmission time delay of the output signal corresponding to the reverse output port according to the output high voltage Voh _ z, the output low voltage Vol _ z and the output three-state pull bias voltage Voz _ z of the reverse output port in each path of differential output port. For example, the alternating current parameters of the pulse signal are tested using a TMU or TIA meter, including the rise time Tr, the fall time Tf, the transmission delay Tphl/Tplh/Tpzl/Tpzh/Tplz/Tphz; the alternating current parameter test reference voltage is calculated by the measurement result of the direct current parameter measurement submodule 107 and can be set through software; the test time resolution can be set by software; the test results of the ac parameter measurement sub-module 108 are provided to the ac parameter measurement result compensation module 106.

Specifically, the reference voltage for the ac parameter test of the channels is calculated according to the Y/Z dc parameters of each channel of differential output ports measured by the dc parameter measuring submodule 107, for example, the low voltage differential driver 104 includes three channels of each channel of differential output ports, which are Y1/Z1, Y2/Z2, Y3/Z3, Y4/Z4, and Y5/Z5, respectively, so that the reference voltage of the channel Tr corresponding to Y1 is Vol _ Y + (Voh _ Y-Vol _ Y) x 0.2 and Vol _ Y + (Voh _ Y-Vol _ Y) x 0.8; the reference voltage of the channel Tr corresponding to Z1 is Vol _ Z + (Voh _ Z-Vol _ Z) multiplied by 0.2 and Vol _ Z + (Voh _ Z-Vol _ Z) multiplied by 0.8; the reference voltage of the channel Tf corresponding to Y2 is Voh _ Y- (Voh _ Y-Vol _ Y) x 0.8 and Voh _ Y- (Voh _ Y-Vol _ Y) x 0.2; the reference voltage of the channel Tr corresponding to Z2 is Voh _ Z- (Voh _ Z-Vol _ Z) multiplied by 0.8 and Voh _ Z- (Voh _ Z-Vol _ Z) multiplied by 0.2; the reference voltage of the channel Tphld and Tplhd corresponding to Y3 is (Voh _ Y-Vol _ Y) multiplied by 0.5; the reference voltage of the channel Tphld and Tplhd corresponding to Z3 is (Voh _ Z-Vol _ Z) multiplied by 0.5; the reference voltage of the channel Tpzh and Tphz corresponding to Y4 is (Voh _ Y-Voz _ Y) multiplied by 0.5; the reference voltage of the channel Tpzh and Tphz corresponding to Z4 is (Voh _ Z-Voz _ Z) multiplied by 0.5; the reference voltage of the channel Tpzl and Tplz corresponding to Y5 is (Voz _ Y-Vol _ Y) multiplied by 0.5; the reference voltage of the channel Tpzl and Tplz corresponding to Z5 is (Voz _ Z-Vol _ Z) × 0.5.

In the system shown in fig. 1, the pulse parameter measurement module 103 and the ac parameter measurement sub-module may use a TMU or TIA meter in an ATE meter to measure the ac parameter. The procedure for measuring AC parameters using the TMU or TIA meter in the ATE meter in the embodiments of the present application is briefly described below.

Fig. 2 shows a schematic circuit diagram for measuring ac parameters by using a TMU or TIA meter according to an embodiment of the present application.

For example, in FIG. 2, the circuit mainly includes an ATE tester and a Loadboard test board. The ATE tester mainly comprises a main control computer, a supporting instrument, a direct current source instrument and a digital channel instrument. The main control computer is a core unit for controlling the instrument, generating a test signal graph and summarizing and analyzing data; the support instrument mainly realizes the power supply and the switch control of the relay matrix; the direct current source instrument supplies power to a Device Under Test (DUT); the digital channels are mainly divided into three groups, which are marked by A, B and C in the figure. Group A is a test input signal (relative to the DUT) for providing test input pulses to the DUT (such as the low voltage differential driver 104 shown in FIG. 1 above), and includes ports A, G, and nG; the group B is a test output signal used for collecting alternating current parameters of the tested device and comprises two groups of ports of Y and Z; the group C is also a test output signal and is used for collecting alternating current parameters of an output signal of the digital channel A, and the group C comprises ports A, G and nG.

The Loadboard test board mainly includes a Device Under Test (DUT) and a matrix array (Relay). In addition, the differential output terminal Y/Z of the device under test needs to be connected with the necessary resistor, capacitor load and Vos bias power supply (not shown in fig. 2).

The specific operation flow of the circuit shown in fig. 2 is as follows:

(1) And the main control computer sends an instruction to the support instrument, controls the support instrument to electrify the Relay matrix, and simultaneously switches the signal output of the Relay to the digital channel C.

(2) The main control computer controls the digital channel A to send a pulse signal, the pulse amplitude is the amplitude Vih required by the alternating current parameter test of the DUT (device under test), and simultaneously controls the digital channel C to acquire the alternating current parameters when the pulse signal reaches 50% Vih, wherein the alternating current parameters comprise positive pulse rising time Tr _ A _50p/Tr _ G _50p and negative pulse falling time Tf _ A _50p/Tf _ G _50p; when there are multiple inputs a, each time parameter is measured separately.

(3) And the main control computer sends an instruction to the support instrument and controls the support instrument to switch the signal output of the Relay to the DUT.

(4) The main control computer controls a digital channel A, applies high level to a G port of a DUT, applies low level to an nG port, applies high level to an A port, and controls a digital channel B to acquire the voltage of output ports Y and Z of the DUT, which are recorded as Voh _ Y and Vol _ Z; when there are multiple inputs Y/Z, each output voltage needs to be measured separately.

(5) The main control computer controls a digital channel A, applies high level to a G port of a DUT, applies low level to an nG port, applies low level to an A port, and controls a digital channel B to acquire the voltage of output ports Y and Z of the DUT, which are recorded as Vol _ Y and Voh _ Z; when there are multiple inputs Y/Z, each output voltage needs to be measured separately.

(6) And the master control computer controls the digital channel A, applies high level to the G port of the DUT, applies low level to the nG port, applies positive pulse to the A port, the pulse amplitude meets the AC parameter test requirement of the DUT, and controls the digital channel B to collect.

a) The time when the DUT output port Y of the device under test reaches Vol _ Y + (Voh _ Y-Vol _ Y) x 0.2, vol _ Y + (Voh _ Y-Vol _ Y) x 0.5, vol _ Y + (Voh _ Y-Vol _ Y) x 0.8 is marked as Tr _ Y _20p, tr _ Y _50p, tr _ Y _80p; when there are multiple inputs Y/Z, each time parameter is measured separately.

b) The time when the output port Z of the DUT reaches Vol _ Z + (Voh _ Z-Vol _ Z) x 0.8, vol _ Z + (Voh _ Z-Vol _ Z) x 0.5, vol _ Z + (Voh _ Z-Vol _ Z) x 0.2 is marked as Tf _ Z _80p, tf _ Z _50p, and Tf _ Z _20p; when there are multiple inputs Y/Z, each time parameter is measured separately.

(7) And the master control computer controls the digital channel A, applies high level to the G port of the DUT, applies low level to the nG port, applies negative pulse to the A port, the pulse amplitude meets the AC parameter test requirement of the DUT, and controls the digital channel B to collect the pulse.

1) The time when the output port Y of the DUT reaches Vol _ Y + (Voh _ Y-Vol _ Y) x 0.8, vol _ Y + (Voh _ Y-Vol _ Y) x 0.5 and Vol _ Y + (Voh _ Y-Vol _ Y) x 0.2 is marked as Tf _ Y _80p, tf _ Y _50p and Tf _ Y _20p; when there are multiple inputs Y/Z, each time parameter is measured separately.

2) The times at which the DUT output port Z of the device under test reaches Vol _ Z + (Voh _ Z-Vol _ Z) x 0.2, vol _ Z + (Voh _ Z-Vol _ Z) x 0.5, vol _ Z + (Voh _ Z-Vol _ Z) x 0.8, respectively, are denoted as Tr _ Z _20p, tr _ Z _50p, tr _ Z _80p; when there are multiple inputs to Y/Z, each time parameter is measured separately.

(8) The main control computer calculates Tr, tf, tphld and Tplhd according to the following method, and when a plurality of differential driving channels exist, each path of time parameter is independently calculated according to 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 master control computer controls a digital channel A, applies low level to a G port of a DUT, applies high level to an nG port, and controls a digital channel B to acquire the voltage of output ports Y and Z of the DUT, which are recorded as Voz _ Y and Voz _ Z; when there are multiple inputs Y/Z, each output voltage needs to be measured separately.

(10) The main control computer controls the digital channel A, applies high level to the A/nG port of the DUT, applies positive pulse to the G port, the pulse amplitude meets the AC parameter test requirement of the DUT, and controls the digital channel B to collect:

a) The time when the output port Y of the DUT reaches (Voh _ Y-Voz _ Y) multiplied by 0.5 is recorded as Tpzh _ Y; when multiple paths of input Y/Z exist, each path of time parameter needs to be measured independently;

b) The time for the DUT output port Z to reach (Voz _ Z-Vol _ Z) × 0.5, denoted as Tpzl _ Z; when multiple paths of input Y/Z exist, each path of time parameter needs to be measured independently;

(11) The master control computer controls the digital channel A, applies high level to the A/nG port of the DUT, applies negative pulse to the G port, the pulse amplitude meets the AC parameter test requirement of the DUT, and controls the digital channel B to collect:

a) The time for the DUT output port Y to reach (Voh _ Y-Voz _ Y) x 0.5, denoted as Tphz _ Y; when multiple paths of input Y/Z exist, each path of time parameter is measured independently;

b) The time for the DUT output port Z to reach (Voz _ Z-Vol _ Z) × 0.5, denoted as Tplz _ Z; when multiple paths of input Y/Z exist, each path of time parameter needs to be measured independently;

(12) The main control computer controls the digital channel A, a low level is applied to the port A of the DUT, a high level is applied to the port nG, a forward pulse is applied to the port G, the pulse amplitude meets the AC parameter test requirement of the DUT, and the digital channel B is controlled to collect:

a) The time when the output port Y of the DUT reaches (Voz _ Y-Vol _ Y) x 0.5 is recorded as Tpzl _ Y; when multiple paths of input Y/Z exist, each path of time parameter needs to be measured independently;

b) The time for the DUT output port Z to reach (Voh _ Z-Voz _ Z) × 0.5 is denoted as Tpzh _ Z; when multiple paths of input Y/Z exist, each path of time parameter needs to be measured independently;

(13) The master control computer controls the digital channel A, applies a low level to the port A of the DUT, applies a high level to the port nG, applies a negative pulse to the port G, the pulse amplitude meets the test requirement of the alternating current parameters of the DUT, and the digital channel B is controlled to collect:

c) The time when the output port Y of the DUT under test reaches (Voz _ Y-Vol _ Y) x 0.5 is marked as Tplz _ Y; when multiple paths of input Y/Z exist, each path of time parameter is measured independently;

d) The time for the DUT output port Z to reach (Voh _ Z-Voz _ Z) x 0.5, denoted as Tphz _ Z; when multiple paths of input Y/Z exist, each path of time parameter needs to be measured independently;

(14) The main control computer calculates Tpzh, tphz, tpzl and Tplz according to the following method, and when a plurality of differential driving channels exist, each path of time parameter is independently calculated according to respective measurement result:

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

according to the scheme provided by the embodiment of the application, when the output alternating current parameters of the low-voltage differential driver are measured, the direct current parameter measuring submodule and the alternating current parameter measuring submodule are connected to the differential output port of the low-voltage differential driver, and the reference voltage of the alternating current parameters of the output signals of the alternating current parameter measuring submodule is calculated through the direct current parameters of the output signals of the direct current parameter measuring submodule. The test result of the direct current parameter is adopted to carry out targeted setting on the test condition of the alternating current parameter, and the problems of test consistency and stability among different channels (differential output ports) of the low-voltage differential driver are effectively solved.

Also by way of example, the pulse generation module 101, the pulse parameter measurement module 103, and the ac parameter measurement submodule 108 are clock synchronized.

Further, in the solution provided in 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 ac parameter of the output signal of the differential output port of the low voltage differential driver 104 output by the differential output parameter measurement module 105. The compensation module 106 may calculate a compensated ac parameter test result output by the low voltage differential driver 104 according to the measurement result (the first ac parameter) of the pulse parameter measurement module 103 and the measurement result (the second ac parameter) of the ac parameter measurement sub-module 108. 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 ac parameter test result output by the compensated low-voltage differential driver 104.

According to the scheme provided by the embodiment of the application, the compensation module 106 is introduced when the alternating current parameter corresponding to the low-voltage differential driver 104 is measured. The compensation module 106 is used for compensating the alternating current parameter test result corresponding to the low-voltage differential driver 104, and the test error caused by 50% of jump time of the input signal is effectively solved. In addition, compare and directly use the alternating current parameter of TMU or TIA instrument test low voltage differential driver in the ATE instrument, the test result of this application embodiment more accords with product manual test requirement, and the test result is more accurate.

The ac parametric test method for the low-voltage differential driver provided in the embodiments of the present application is further described in detail below with reference to the drawings in the specification, and a specific implementation manner of the method may include the following steps (a method flow is shown in fig. 3):

step 301, the pulse generating module generates a pulse signal and sends the pulse signal to the pulse output module and the pulse parameter measuring 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 measuring module receives the pulse signal, measures a first ac parameter of the pulse signal, and sends the first ac parameter to the compensation module.

And 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 and 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 to obtain compensated ac parameters corresponding to the low-voltage differential driver according to the first ac parameters and the second ac parameters.

Further, in a solution provided in an embodiment of the present application, in a process shown in fig. 3, a 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 a compensation module, where the process includes: the direct current parameter measurement submodule measures direct current output voltage of each path of differential output port; and the alternating current parameter measuring submodule calculates corresponding alternating current output voltage according to the direct current output voltage of each path of differential output port.

Specifically, in the solution provided in the embodiment of the present application, a brief flow of the method for testing the communication parameters is shown in fig. 4, and includes the following processes: the method comprises the steps of input pulse 50% jump delay testing, low-voltage differential driver differential output signal direct current parameter testing, differential signal alternating current parameter testing criterion reference voltage setting and alternating current parameter testing result compensation calculation.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present application without departing from the spirit and scope of the application. Thus, if such modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is intended to include such modifications and variations as well.

Claims (10)

1. An AC parametric test system for low voltage differential drivers, comprising: the device comprises 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 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 is 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 outputting differential signals according to the pulse signals;

the differential output parameter measuring 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 configured to calculate, according to the first alternating current parameter and the second alternating current parameter, a compensated alternating current parameter corresponding to the low-voltage differential driver.

2. The system of claim 1, wherein the pulse signals generated by the pulse generation module include positive pulse signals inputting a low level voltage to an input high level voltage and negative pulse signals inputting a high level voltage to an input low level voltage.

3. The system of claim 2, wherein the pulse output module comprises a set of input ports, a first set of output ports, and a second set of output ports; the input port and the first group of output ports form a first channel, and the input port and the second group of output ports form a second channel; the first channel is used for sending the pulse signal to the pulse parameter measuring 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 the pulse output module sends the pulse signal to the pulse parameter measurement module through the first channel at a specified time; or sending the pulse signal to the low-voltage differential driver through the second channel.

5. The system of any one of claims 1-4, wherein the low voltage differential driver includes at least one differential output port;

the differential output parameter measuring module comprises a direct current parameter measuring submodule and an alternating current parameter measuring submodule; wherein,

the direct-current parameter measuring submodule is coupled with the low-voltage differential driver and the alternating-current parameter measuring submodule and is used for measuring direct-current output voltage of each path of differential output port;

and the alternating current parameter measuring submodule is used for calculating corresponding alternating current output voltage according to the direct current output voltage of each path of differential output port.

6. The system of claim 5, wherein each of the differential output ports comprises a forward output port and a reverse output port;

the direct current output voltage comprises an output high voltage Voh _ y, an output low voltage Vol _ y and an output three-state pull bias voltage Voz _ y of a forward output port in each path of differential output port; and the output high voltage Voh _ z, the output low voltage Vol _ z and the output three-state pull bias voltage Voz _ z of the reverse output port in each path of differential output port.

7. The system of claim 6, wherein the AC parameter measurement submodule calculates a rise time, a fall time and a transmission delay of an output signal of the forward output port according to the output high voltage Voh _ y, the output low voltage Vol _ y and the output three-state bias voltage Voz _ y of the forward output port in each path of the differential output port; and

and calculating the rising time, falling time and transmission time delay of the output signal corresponding to the reverse output port according to the output high voltage Voh _ z, the output low voltage Vol _ z and the output three-state pull bias voltage Voz _ z of the reverse output port in each path of differential output port.

8. The system of claim 7, wherein the pulse generation module, pulse parameter measurement module, and ac parameter measurement sub-module are clock synchronized.

9. An alternating current parameter testing method 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 a pulse parameter measuring module and a low-voltage differential driver;

the pulse parameter measuring module receives the pulse signal, measures a first alternating current parameter of the pulse signal and sends the first alternating current 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 measuring module;

the differential output parameter measuring module receives the differential signal and measures a second alternating current parameter of the differential signal, and sends the second alternating current parameter to the compensation module;

and the compensation module calculates to obtain compensated alternating current parameters corresponding to the low-voltage differential driver according to the first alternating current parameters and the second alternating current parameters.

10. The method of claim 9, wherein the differential output parameter measurement module comprises a direct current parameter measurement sub-module and an alternating current parameter measurement sub-module; wherein,

the differential output parameter measurement module receives the differential signal and measures a second alternating current parameter of the differential signal, and sends the second alternating current parameter to the compensation module, and the differential output parameter measurement module comprises: the direct current parameter measuring submodule measures direct current output voltage of each path of differential output port; and the alternating current parameter measuring submodule calculates corresponding alternating current output voltage according to the direct current output voltage of each path of differential output port.

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