Model 4280A 1MHz C Meter / C-V Plotter
Contents
1. V LIMIT RNG HOLD Key This key is used to set the maximum allowable output from the internal de bias source during non sweep constant bias measurements C mode It also sets the range and therefore the resolution of the output voltage To set the output voltage limit press the Blue key press the V LIMIT RNG HOLD key the previously set limit or u will appear on the display 8 key in the desired limit with the numerie keys and then press ENTER 10 Refer to paragraph 3 62 for details Numerie Keys These keys 0 through 9 decimal point and minus sign are used for entering parameter values MATH funetion reference values and other numerie data Press ENTER to validate numerie data that has been keyed in C OFFSET Keys Option 001 only These keys are used with the C HIGH RESOLN key to enter capacitance offset values Refer to paragraph 3 161 for details MEASURED Pressing this key and then the ENTER key when the C HIGH RESOLN key is on key indicator lamp is lit sets e measured capacitance value as the offset value MANUAL This key is used to manually set the capacitance offset value with the numeric key 3 and ENTER key 19 Figure 3 2 Front Panel Features Sheet 11 of 12 Model 4280 SECTION III 83 C REF G REF Keys G REF This key is for entering conductance These keys are used to store reference referenee values It funetions in the values for the MATH funetions2. The ground terminal 2L is tied directly to the instrument s chassis and to the earth terminal offset pin of the LINE input receptaele in Figure 3 3 on the rear panel The MEAS COMMON terminal is tied directly to the common of the instrument s measurement circuit and to the outer shields of the UNKNOWN terminals These terminals be intereonneeted with the attached shorting strap AWARNING THE GROUND REFERENCED POTENTIAL ON THE EXPOSED OUTER SHIELDS OF THE UNKNOWN TERMINALS AND ON THE MEAS CKT COMMON TERMINAL v CAN BECOME DANGEROUSLY HIGH WHEN THE GROUND 4 AND MEAS CKT COMMON TERMINALS ARE NOT INTERCONNECTED Figure 3 2 Front Panel Features Sheet 10of 12 SECTION Model 4280A 4280A 1MMz C METER C V PLOTTER twi PACKARD CORRECTION 0 03 109 0 SRST X et ee RE DIGIT RES X Y RECORDER 1010 UR TRIGGER Int EXT HOLOs Man Blue shift Functions The following functions are labelled in blue on the front pane They are available when the Blue key is on when the key indicator lamp is Ht ms millisecond Key This key is used when entering time parameters Pressing this key after a time value has been keyed in with the numeric keys G changes the time unit from seconds to milliseconds The ms unit indicator lamp on the V t display 8 will light
3. CURRENT APPLIED TO EXT BIAS CONNECTORS TO EXCEED 100 DOING SO MAY RESULT IN DAMAGE TO THE 4280A AWARNING DO NOT ALLOW DC BIAS VOLTAGE APPLIED TO EXT BIAS CONNECTORS TO EXCEED 42V OR DANGEROUS VOLTAGE MAY APPEAR AT THE MEASUREMENT TERMINALS 5 SYNC OUTPUT Connector This BNC connector is used for C t mode measurements in which the bias pulse is supplied from an external de bias source A TTL level HIGH is output from this connector during the th period of the measurement Refer to paragraph 3 126 for details Figure 3 3 Rear Panel Features Sheet 1 of 2 SECTION III Model 4280A EXT E INT INT xT 9 ud Qe XE Bias Initial control setting Wafer I Chuck Chuck Insulator 4 Insulator Table Figure 3 12 Connection Using a Wafer Prober 3 32 SECTION TII 3 37 Figure 3 12 shows two methods of using a wafer prober to connect a test sample to the 4280A If the ehuek of the wafer prober is not grounded as shown in A the test sample is considered floating Conversely if the chuck is grounded as in B the test sample which is in contact with the chuck is considered grounded Note If the impedance between the grounded terminal of the sample and ground is low disconnect the shorting strap that interconnects the ground terminal L and the MEAS CKT COMMON terminal on the front panel 3 38 EQUIVALENT CIRCUITS 3 39 Any eomplex i
4. and to same manner as the C REF key recall display previously stored reference values CONN MODE Key C REF Pressing this key while the Blue This key is used to select the connection key is on displays the stored mode with the numerie keys and reference values for capacitance ENTER key Refer to paragraph 3 31 and conductance on the for details display display X 7 respectively Also EF is displayed on the display A capacitance reference value be entered with the numeric keys 31 and the ENTER key Q Figure 3 2 Front Panel Features Sheet 12 of 12 SECTION 3 14 Model 4280A HP IB Connector Twenty four pin connector Connects the instrument to the Hewlett Packard Interface Bus for remote operation HP IB Address Switehes These rotary switches set the instrument s HP IB address 0 to 30 for ADDRESSABLE operation and the data delimiter 50 CR LF and 51 comma for TALK ONLY operation Refer to paragraph 3 164 for details EXT TRIGGER Connector This BNC connector is for triggering the instrument with an external triggering device or a TTL level signal TRIGGER SWEEP MODE must be set to EXT Details are given in paragraph 3 54 EXT BIAS Conneetors A These BNC connectors F AST and SLOW are used in measurements that require an external bias source Refer to paragraph 3 100 for details ACAUTION DO NOT ALLOW DC BIAS
5. of the internal de bias source and in some respects determines the measurement mode Selectable funetions depend on connection mode Each function is briefly described below Sets the 4280A to C V mode The internal de bias source will sweep its output in an up down staircase fashion in accordance with the previously entered sweep parameters 27 Single Stairease Bias Sweep Sets the 4280A to C V mode The internal de bias source will sweep its output in a single stairease fashion in aecordanee with the previously entered sweep parameters DC Bias Sets the 4280A to C mode non sweep The internal de bias source will output the previously entered bias voltage OFF Sets the 4280A to C mode non sweep Turns off the internal de bias source The following three functions are labelled in gray on the front panel and are selectable only when the instrument is in C t mode see FUNCTION 19 lr Pulsed Bias The internal de bias source outputs a pulse whose height and width are determined by the previously entered PULSE V th parameters respectively and then outputs the specified MEAS V voltage for the remainder of the measurement sequence DC Bias This funetion is used for connection modes requiring pulsed biasing from an external voltage source The internal de bias souree outputs the previously entered bias voltage after the bias pulse period determined by th OFF Turns off the intern
6. 3 3 on the rear panel Measurement is made each time a positive going TTL level pulse is applied to the center conductor of the connector HOLD MAN This key is for manual triggering Measurement is made each time this key is pressed Measurement data is held until the key is pressed again REPEAT When this mode is selected in C V or C t mode swept measurements are started y andar the SWEEP V OUTPUT key and are repeated until the SWEEP V TPUT key is pressed again EXT When this mode is seleeted in C V or C t mode single sweep measurement is started by an external trigger signal applied to the EXT TRIGGER connector Gin Figure 3 3 on the rear panel INGE When this mode is selected in C V or C t mode single sweep measurement is started by ressing the SWEEP V OUTPUT key Figure 3 2 Front Panel Features Sheet 6 of 12 3 7 SECTION III Model 4280A GROUNDED tow amp o o OO o FUNCTION Select Keys These keys select the measurement function and when the Blue key is on key indicator lamp is lit change the measurement mode from C mode non sweep or C V mode bias sweep to C t mode time sweep and baek again When the instrument is in C mode or C V mode the indicator lamp on the selected function key lights continuously and the functions labelled in blaek C G C and G are valid When the instrument is i
7. EA X Ser caco go reer X Y RECORDER vom W TURO TRIGGER wr EXT MOLON GG SWEEP MODE WARNING DO NOT USE THE FURNISHED BNC SHORTING CAP FOR GROUNDING THE REMOTE ON OFF CONNECTOR Limit Switeh This switch limits the output voltage from the internal de bias souree It also functions as a mechanical stop when set to the 100 MAX position preventing eonneetion of test fixtures designed for low voltage measurements 100V MAX Maximum output 100 from the internal de bias source is possible Connection of HP test fixtures designed for use at 42V and below is made physieally impossible The eenter conductor of the REMOTE ON OFF connector must be grounded to enable output from the internal de bias source 42V MAX Output from the souree is limited to ensure operator safety internal de bias 42 volts to Figure 3 2 Front Panel Features Sheet 9 of 12 C UNKNOWN Terminals A 1 4280 These two BNC connectors the 4280A s measurement terminals They have a two terminal pair configu ration HIGH terminal and LOW terminal Two terminal pair test fixtures such as the furnished 16080A connect directly to these terminals AWARNING WHEN BIAS VOLTAGE IS USED DANGEROUS VOLTAGE MAXIMUM 100V MAY APPEAR THESE TERMINALS Ground MEAS COMMON SECTION III Terminals
8. IGIT SHIFT Keys These keys are related to the 4280A s X Y RECORDER function They reduce the umber of digits displayed on the C display and G display to prevent the G and G recorder outputs in Figure 3 3 from saturating Refer tO paragraph 3 156 for details Co Eaeh time this key is pressed the least significant digit right most digit of the_number appearing on the C display is deleted The new number is automatically rounded and shifted one display position to the right Only digits to the right of the decimal point can be deleted The complete number be redisplayed by repeatedly pressing this key until the key indicator lamp goes off This key does not function when the C display is turned off FUNCTION is set to G Funetions identically to the C okey described above for numbers appearing on the G display This key does not function when the G display is turned off FUNCTION is set to C Figure 3 2 Front Panel Features Sheet 5 of 12 STORE DISPL C G Key Model 4280A Pressing this key stores the values displayed on the C display and G display 7 The stored values are uSed as reference values in ealeulations made by the 4280A s MATH functions MATH Previously stored reference values are erased and replaced with displayed values each time this key is pressed If the C or display is turned off FUNCTION 19 is set to C or G when this key is pressed the previously stored reference val
9. Model 4280A SECTION SECTION Ill OPERATION 3 1 INTRODUCTION PROTECTIVE EARTH GROUNDED SOCKET ANY INTERRUPTION 3 2 This section provides all the information OF THE PROTECTIVE EARTH necessary to operate the Model 4280A 1MHz C METER C V PLOTTER Ineluded are deseriptions of the front and rear panel controls displays lamps and connectors discussions on operating procedures and measurement techniques for various applications instructions on the instrument s SELF TEST function Warnings Cautions and Notes are given throughout they should be observed to insure the safety of the operator and the serviceability of the instrument WARNING BEFORE THE INSTRUMENT IS SWITCHED ON ALL PROTECTIVE EARTH TERMINALS EXTENSION CORDS AUTO TRANSFORMERS AND DEVICES CONNECTED TO IT SHOULD BE CONNECTED TO A GROUNDING WILL CAUSE A POTENTIAL SHOCK HAZARD THAT COULD RESULT IN SERIOUS PERSONAL INJURY ONLY FUSES OF THE CORRECT CURRENT RATING AND OF THE SPECIFIED TYPE SHOULD BE USED DO NOT USE REPAIRED FUSES OR SHORTED FUSE HOLDERS TO DO SO COULD CAUSE A SHOCK OR FIRE HAZARD CAUTION BEFORE THE INSTRUMENT IS SWITCHED ON IT MUST BE SET TO THE VOLTAGE OF THE POWER SOURCE MAINS OR DAMAGE TO THE INSTRUMENT MAY RESULT OPERATING INSTRUCTIONS paragraphs 3 3 through 3 57 C Mode paragraphs 3 58 through 3 69 C V Mode paragraphs 3 70 through 3 85 Extended Capabilities RECORDER OUTPUTS paragraphs 3 156 th
10. The cable must be open terminated during SECTION calibration At the completion of the calibration sequence the CAL key indicator lamp will go off automatically After performing ZERO OPEN 23 the ENABLE key will funetion normally G Trigger Lamp This lamp comes on each time the instrument is internally externally manually triggered Trigger mode is set by the TRIGGER keys 18 When INT TRIGGER mode is selected the trigger lamp flashes at the internal measurement rate C Display and Unit Indicators Displays measured values of capacitance the instrument s HP IB address at turn gn ealeulation results see MATH 13 ealeulation reference values see STORE DISPL 09 and 33 C OFFSET values option 001 only see C HIGH RESOLN Q1 AND C OFFSET 3 and various messages and error codes SELF TEST Maximum number of display digits and maximum display eount depend on the type of measurement being made option installation and certain control settings The C display is turned off blank for G G t measurements Unit indicators nF pF show the appropriate unit for the displayed value G Display and Unit Indicators Displays measured values of conductange ealeulation results see MATH 14 calculation reference values see STORE DISPL 16 and G REF 09 and messages related to the X Y RECORDER function Maximum number of display digits and maximum display count depend on t
11. al de bias source Figure 3 2 Front Panel Features Sheet 4 of 12 3 5 SECTION 3 6 Model 4280A 4280A 1MHz C METER C V PLOTTER MEWLETT PACKARD UNKNOWN Low CD MATH Keys These keys instruct the 4280A to calculate difference A percent and percent difference A Once pressed the key remains on key indieater lamp on until it is pressed again or until another MATH key is pressed When one of these keys is_pressed values displayed on the C display 6 and G display calculation results not measured values A difference Calculates the difference between the measured value of the device under test and a previously stored reference value The formula used is A B where A is the measured value of the device under test and B is the stored reference value percent Computes the percentage relationship between the measured value of the device under test and a previously stored reference value The formula used is A 100 B x where and B are as described above in the explanation of the Akey pereent difference Computes the percent difference between the measured value of the device under test and a previously stored referenee value The formula used is z x 100 5 where as described in the exlanation of the Akey 19 D
12. ally seleet the measurement range that best suits the value of the device under test MANUAL When this key is pressed the AUTO key indieator lamp will go off and the measurement range will be fixed at the selected range To change measurement range press this key To return to AUTO ranging mode press the AUTO key C HIGH RESOLN Key Option 001 Only This key enables high resolution capacitance measurements It is used in conjunction with the CORRECTION ENABLE key and the C OFFSET keys G3 Refer to paragraph 3 161 for details SECTION SELF TEST Key This key initiates the instrument s SELF TEST funetion During SELF TEST key indicator lamp is on eight tests that cheek the basie operation of the instrument are automatically performed Nothing must be connected to the UNKNOWN terminals during the test SELF TEST is repeated until this key is pressed again If an abnormality is detected an error_code will be displayed on the C display SELF TEST error codes are described in paragraph 3 7 When SELF TEST is canceled the instrument is set to its initial control settings If this key is pressed unintentionally control settings be maintained by quickly pressing this key again while 5 F is displayed on the C and G displays Refer to paragraph 3 7 for eomplete details on SELF TEST SIG LEVEL Select Key and Indicators This key selects the test signal level 30mVrms
13. as been keyed in with the Numeric keys Figure 3 2 Front Panel Features Sheet 3 of 12 Model 4280A SECTION Blue Key f Double Staircase Bias Sweep This key must be pressed to access functions labelled in blue Once pressed the blue key remains on key indicator lamp is lit until a blue funetion key and the ENTER key 10 have been pressed or until the blue key is pressed again SWEEP V OUTPUT Indicator and Key The V OUTPUT red indicator lamp comes on when the 4280A is performing a biased internal de bias source non sweep measurement in C mode or a swept bias or time measurement in C V or C t mode The SWEEP V OUTPUT gold eolored key START STOP SET RESET starts and stops swept measurements in C V and C t modes and sets turns on and resets turns off the internal de bias source in C mode Under eertain eombinations of measurement mode and eonneetion mode if INTERNAL BIAS is set to OFF this key does not funetion Operation of this key depends also on the PM mode see TRIGGER SWEEP MODE Note The V OUTPUT lamp blinks on and off when the eurrent through the DUT exceeds the output capability of the internal de bias source WARNING IF V OUTPUT LAMP BLINKS ON AND OFF WHEN NOTHING 15 CONNECTED TO THE UNKNOWN TERMINALS THE 4280A Is MALFUNCTIONING AND DANGEROUS VOLTAGE MAY BE PRESENT THE UNKNOWN TERMIN ALS INTERNAL BIAS Key and Indieators This key selects the function
14. epends on the ec nneetion mode see CONN MODE 4 and internal bias mode see INTERNAL BIAS 13 A brief deseription of each parameter is given below DC V V Voltage output from the internal de bias souree used in C mode START V V Start Voltage for bias sweeps made with the internal de bias souree used in C V mode STOP V V Stop voltage for bias sweeps made with the internal de bias source used in C V mode STEP V V Step voltage for bias sweeps made with the internal de bias souree used in C V mode HOLD TIME 5 Hold time for the START and STOP voltages of a bias sweep made with the internal de bias source used in C V mode STEP DELAY TIME S Delay time for each STEP voltage of bias sweep made with the internal de bias source used in C V mode The following six parameters are labelled in gray on the front panel and are selectable only when the instrument is in C t mode see FUNCTION 19 DC V V Voltage output from the internal de bias source PULSE V V Pulsed bias voltage output from the internal de bias source MEAS V V Voltage output from the internal de bias source after the bias pulse PULSE V is removed NO OF READINGS Number of measurements th s Duration of bias pulse internally and externally supplied td s Time between measurements ENTER Key This key must be pressed after parameter value referenee value or connection mode number h
15. he type of measurement being made and certain eontrol settings The G display is turned off blank for C C V and C t measurements Unit indieators mS uS show the appropriate unit for the displayed value Display and Unit Indicators Displays bias voltage settings time settings eonneetion modes error eodes related to illegal operation and messages for special measurements for example 5 L for CABLE LENGTH CAL P for ZERO OPEN Unit indieators V s ms show the appropriate unit for the displayed value Figure 3 2 Front Panel Features Sheet 2 of 12 SECTION III 3 4 Model 4280A 4280A 1MHz METER C V PLOTTER MEWLETT PA UNKNOWN Low Tj 142V 00 0 o esi INT BIAS A ZERO REMOTE ON OFF T X Y RECORDER JE C SWEEF Y TRIGGER EXT HOLD MAN START STOP O SETZRESET m PARAMETER Select Keys and Indieators These keys select voltage time parameters for entry The entered value of the selected parameter indicator lamp on is displayed on the V t display To enter a parameter value repeatedly press the 9 or 6 key until the indicator lamp adjaeent to the desired parameter is lit Then press the Blue key key indieator lamp will eome on and key in the desired value with the Numerie keys Finally press the ENTER key Parameter selection d
16. mpedanee ean be represented by simple series or parallel equivalent eireuit consisting of a single resistive element and a single reactive element This is possible because both equivalent circuits have identical impedances at a given test frequency if the equivalent circuit elements are properly established The 4280A measures the capacitance C and conductance G of the equivalent parallel circuit of the device eonneeted to the UNKNOWN terminals 3 40 The capacitance value obtained from an equivalent parallel circuit measurement will differ from the value obtained from equivalent series cireuit measurement The difference is due to the loss of the device being measured The higher the loss the larger the difference The impedance of the device under test whether measured as an equivalent parallel eireuit or equivalent series circuit is the same at any given frequency This ean be proven mathematically as follows Model 4280A Expanding we have R 3 1 m G Lv ds WCp J acs 62 wt GZ 02 2 where Cp is the equivalent parallel circuit capacitance B w and Cs is the equivalent series circuit capacitance 1 wX Obviously if the device under test has no losses that is if series resistance R and parallel conductance G are both zero equivalent series capacitance Cs and equivalent parallel capacitance Cp will be equal The correlation between Cs and Cp ean be easily determined by using simple eon
17. n C t mode the indicator lamp on the selected function key flashes off and on and the funetions labelled in grey C t and G t are valid C G When C G is selected the 4280A measures both eapaeitanee C and equivalent parallel conductance G When C G is selected only capacitance only conductance respectively is measured The 4280A is in C mode when INTERNAL BIAS is set OFF it is in C V mode when INTERNAL BIAS is set to g y Op sr INT BIAS A z ACMOTE rov Max ON OFF Open BH o e C G t C t G t These functions are available only when the 4280A is in C t mode time sweep To set the instrument to C t mode press the Blue key key indieator lamp should eome on and then press the desired FUNCTION key The indieator lamp at the center of the key will begin to flash The other two functions ean now be selected directly without the Blue key To change back to C mode or C V mode press the Blue key again and then press the function key whose indicator lamp is flashing Figure 3 2 Front Panel Features Sheet 7 of 12 RANGE Keys and Indicators Model 4280A These keys select the ranging mode AUTO or MANUAL and the measurement range The three adjacent indicator lamps show the selected measurement range AUTO When the indieator lamp at the eenter of this key is on the 4280A is in AUTO ranging mode and will automatie
18. nd test leads ENABLE Enables internal correction calculations using stored constants and ZERO OPEN e data When the correction mode is released ENABLE key indicator lamp off internal correction X ealeulations not performed thus reducing measurement time CABLE LENGTH Selects the nominal cable length for use in the internal correction routines The selected cable length should agree with the test fixture or test leads connected to the UNKNOWN terminals The lighted indicator lamp shows the selected cable length 0 m Select this setting when using direet attaehment type test fixture for example the furnished 16080A Test Fixture l m Select this setting when using the 16082A one meter test leads 0 5 m Select this setting when using test leads that are shorter or longer up to 5m than one meter for example the 16081A two meter test leads or test leads made from PN 8120 4195 coaxial cable CABLE LENGTH ealibration must be performed CAL and START This key and button function only when the 0 5 m eable length setting is selected Pressing CAL lights the key indicator lamp and enables CABLE LENGTH ealibration Pressing the START button initiates the calibration sequence During calibration the 4280A measures the capacitance of the cable conneeted to the UNKNOWN HIGH terminal 2 and Stores the results displayed on the C and G displays that will be used in the correction calculations
19. or 10mVrms The adjacent indicator lamps show the selected test signal level MEAS SPEED Select Key and Indicators This key selects the measurement speed FAST MED and SLOW Actual measurement speed depends on the control settings and the value of the device under test The adjacent indicator lamps show the selected measurement speed Figure 3 2 Front Panel Features Sheet 8 of 12 SECTION IH G3 ZERO OPEN Button This button is for ZERO offset compensation of the stray capacitance and conductance inherent in the test fixture test leads and measurement circuit When this key is pressed the test fixture or test leads must be terminated open nothing connected INT BIASA This slide switch and BNC connector are safety features that respectively limit and shut down the output from the internal de bias source REMOTE ON OFF This connector is used for remote on off eontrol of the internal de bias source when the adjacent slide switch is set to the 100V MAX position When the center conductor of this connector is grounded mechanically or electrically the internal de bias source outputs the specified voltage When the center conductor is left open or when a TTL level HIGH is applied to it output from the internal de bias source is shut down AXCAUTION DO NOT APPLY AN DC BIAS VOLTAGE TO CONNECTOR EXTERNAL THIS OF 0 Model 4280A four
20. rough 3 160 C t Mode paragraphs 3 86 through 3 155 Figure 3 1 Contents of Section III SECTION 3 3 OPERATING INSTRUCTIONS 3 4 Operating instructions for the instrument s basie capabilities are given in paragraphs 3 3 through 3 57 Operating instructions for Extended Capabilities X Y Recorder Outputs C High Resolution measurement remote operation via the HP IB are covered in paragraphs 3 156 through 3 224 Model 4280A 3 5 PANEL FEATURES 3 6 Figures 3 2 and 3 3 identify and briefly describe the purpose of each key indicator and eonneetor on the front and rear panels respectively Detailed information on front panel displays and controls is given starting in paragraph 3 7 UNKNOWN mae 242V 52 0000 EOS INT 61AS A REMOTE 2100 N OPEN a taav MAX ao x ax IGIT SHIFT RTS X Y RECORDER ZERO VR INTERNAL TET moun SAS AIO 3525 go SEV RESETS w lean ee A Meia 1 LINE OFF ON Applies ae line power to the instrument when set to the ON position Removes ae line power when set to the OFF N position HP IB Status Indicators and LOCAL Key These four LED lamps LTN SRQ TLK and RMT listen service request talk remote respeetively indieate the status of the 4280A when it is interfaced with a eomputer or a listen only device printer for example
21. ue of the turned off display is not updated X Y RECORDER Keys These keys are used when setting the lower left upper right and absolute zero scaling points on an X Y recorder connected to the recorder outputs RECORDER OUTPUTS 11 in Figure 3 3 on the rear panel They funetion when TRIGGER E is set to HOLD MAN or when the 42804A is in C V or C t mode and is not measuring LL lower left When this key is pressed 10V is output from each recorder output connector on the rear panel The lower left scaling point X and Y minimum on the X Y recorder be set ZERO absolute zero When this key is pressed 0V is output from each recorder output connector on the rear panel The absolute mid point of the plot area on the X Y recorder ean be set UR upper right When this key is pressed 10V is output from each recorder output connector on the rear panel The upper right sealing point X and Y maximum on the X Y recorder ean be set TRIGGER SWEEP MODE Select Keys SECTION IH These keys seleet the trigger mode for non sweep measurements C mode and the sweep mode for swept measurements C V and C t modes INT This key selects internal triggering Measurement is made at a rate equal to that of the internal trigger signal EXT This key selects external triggering An external trigger device or a TTL level trigger signal must be eonneeted to the EXT TRIGGER eonneetor G in Figure
22. version formula that considers the dissipation factor Refer to Table 3 5 In short capacitance values obtained from equivalent series circuit and equivalent parallel circuit measurements are nearly equal when the dissipation factor D of the device is less than 0 03 The dissipation factor of a component measured at a given frequency will be the same for both series and parallel equivalents Table 3 5 Dissipation Factor Equations and Equivalent Circuit Conversion Formulas oie i 3 34 Equivatent Dissipation Conversion to Other Modes Circuit Factor Cp 1 Q 1 D 2 Cp R T i Ce Cs 6 peur p 1 Model 4280 SECTION Hold Time tH Step Oeloy Time s t Meosurement Time ag tH Hold Time 1 Step Delay Time 15 Measurement Time 5018 z 1 ts itm tS tS ts itm ts Figure 3 20 Bias Sweep Set up Procedure Sheet 1 of 3 3 54
23. via the HP IB The LOCAL key when pressed releases the instrument from remote RMT HP IB control enabling front panel control The LOCAL key is disabled does not funetion when the instrument is set to loeal lockout by the eontroller CONNECTION MODE These keys change the 4280A s internal circuitry to allow floating or grounded measurements FLOATING and GROUNDED are the 4280 5 basic eonnection modes Many more connection modes are also possible Refer to CONN MODE and paragraph 3 31 FLOATING Pressing this key automatically eonfigures the UNKNOWN terminals for a floating measurement Connect the DUT as shown in the drawing adjacent to the key When this key is pressed the key indicator lamp comes on and LO CONNECTION MODE 10 appears the Vet display 8 This connection mode ean be selected with the CONN MODE key also The FLOATING key indieator lamp comes on and connection mode code appears on the V t display GROUNDED Similar to the FLOATING key except that the UNKNOWN terminals C are configured for a grounded measurement CONNECTION MODE 15 m 5 is displayed on the V t display Connect the DUT as shown in the drawing adjacent to the key 3 2 Figure 3 2 Front Panel Features Sheet 1 of 12 Model 4280A 4 CORRECTION This key group provides internal correction of measurement errors caused the parasitic elements of the measurement circuit test fixture a
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