Hệ thống sourcemeter Keithley 6514 Programmable Electrometer

Keithley 6514

Hệ thống sourcemeter Keithley 6514 Programmable Electrometer

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Model

Bảo hành

Keithley

6514

12 tháng

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Mô tả

Hệ thống sourcemeter để bàn Keithley 6514 Picoammeter Voltage Source

The Model 6514 Electrometer combines flexible interfacing capabilities with current sensitivity, charge measure ment capabilities, resolution, and speed that are equal or superior to our earlier electrometers. The Model 6514’s built-in IEEE-488, RS-232, and digital I/O interfaces make it simple to  configure fully automated, high speed systems for low-level testing.

The 5½-digit Model 6514 is designed for applications that demand fast, yet precise measurements of low currents, voltages from high resistance sources, charges, or high resistances.

The Model 6514’s exceptional measurement performance comes at an affordable price. While its cost is comparable with that of many high end DMMs, the Model 6514 offers far greater current sensitivity and significantly lower voltage burden (as low as 20µV) than other instruments can provide.

R&D on a Budget

The Model 6514 offers the flexibility and sensitivity needed for a wide array of experiments, providing better data far faster than older electrometer designs. Applications include measuring currents from light detectors and other sensors, beam experiments, and measuring resistances using a current source. In addition to use by researchers in areas such as physics, optics, and materials science, the Model 6514’s affordable price makes it an attractive alternative to high end DMMs for low current measurement applications, such as testing resistance and leakage current in switches, relays, and other components. For more information on how the Model 6514 does this, refer to the section titled “Low Voltage Burden.”

The Model 6514 builds on the features and capabilities of the Keithley electrometers that preceded it. For example, like those instruments, a built-in constant current source simplifies measuring resistance.

Two analog outputs—a 2V output and a preamp output—are available for recording data with strip-chart recorders.

Economical Component Testing

Once, electrometers were simply considered too slow to keep up with the high throughput that production test applications demand. The Model 6514 is designed for fast, sensitive measurements, providing speeds up to 1200 readings per second with fast integration or 17 measurements per second with 60Hz line-cycle integration. It offers 10fA resolution on 2nA signals, settling to within 10% of the final value in just 15ms. A normal-mode rejection ratio (NMRR) of 60dB allows making accurate low current measurements, even in the presence of line frequency induced currents, which is a common concern in production floor environments. The instrument’s sensitivity makes it easy to determine the leakage resistance on capacitances up to 10nF or even on higher capacitances when a series resistor is used.

While the Model 6514 can be easily operated manually using the front panel controls, it can also be externally controlled for automated test applications. Built-in IEEE-488 and RS-232 interfaces make it possible to    program all instrument functions over the bus through a computer controller. The instrument’s interfaces also simplify integrating external hardware, such as sources, switching systems, or other instruments, into the test system. A digital I/O interface can be used to link the Model 6514 to many popular component handlers for tight systems integration in binning, sorting, and similar applications.

These features make the Model 6514 a powerful, low cost tool for systems designed to test optical devices and leakage resistance on low-value capacitors, switches, and other devices, particularly when the test system already includes a voltage source or when the source current/measure voltage technique is used to determine  resistance.

Figure 1. Dark Current Measurement with Burden Voltage Uncorrected

Figure 2. Dark Current Measurement with Burden Voltage Corrected

Figure 3. Errors Due to Burden Voltage when Measuring with a DMM

Low Voltage Burden

The Model 6514’s feedback ammeter design minimizes voltage offsets in the input circuitry, which can affect current measurement accuracy. The instrument also allows active cancellation of its input voltage and current offsets, either manually via the front panel controls or over the bus with IEEE-488 commands.

Dark Current Measurements

When measuring dark currents (Figure 1) from a device such as a photodiode, the ammeter reads the sum of two different currents. The first current is the dark current (I D ) generated by the detector with no light falling upon the device (in other words, the signal of interest); the second one is the leakage current (I L ) generated by the voltage burden (V BURDEN ) appearing at the terminals of the ammeter. In a feedback ammeter, the primary “voltage burden” is the amplifier offset voltage. This leakage current represents an error current. Without the use of cancellation techniques, I L  = V BURDEN /R L . Figure 2 illustrates how the Model 6514’s CAL V OFFSET  is adjusted to cancel V BURDEN  to within the voltage noise level of a few microvolts, so the measured current is only the true dark current (I D ) of the photodiode. In a similar manner, offset currents can also be cancelled. Earlier electrometers used an internal numerical correction technique in which the voltage burden was still present, so the measured dark current included the error term I L  = V BURDEN /R L .

Voltage Burden and Measurement Error

Electrometers provide current measurement with lower  terminal voltage than is possible when making DMM meas urements. As shown in Figure 3, DMMs measure current using a shunt resistance that develops a voltage (typically 200mV full-range) in the input circuit. This creates a terminal voltage (V BURDEN ) of about 200mV, thereby lowering the measured current. Electrometers reduce this terminal  voltage by using the feedback ammeter configuration  illustrated in Figure 1. The Model 6514 lowers this terminal voltage still further—to the level of the voltage noise—by canceling out the small offset voltage that remains, as shown in Figure 2. Any error signals that remain are  negligible in comparison to those that can occur when measuring current with a DMM.

DMM Offset Currents

Typically, offset currents in DMMs are tens or hundreds of picoamps, which severely limits their low current measuring capabilities compared to the Model 6514 with 3fA input bias current.

Applications

  • Current sensitivity, coupled with low-voltage burden, makes it ideal for:
  •  Photodiode dark-current measurements
  •  Measurement of charge imparted to photocopier toner
  •  Radiation dosimetry measurements

 

 

 

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Keithley

GENERAL SPECIFICATIONS
OVERRANGE INDICATION Display reads “OVRFLOW.”
RANGING Automatic or manual.
CONVERSION TIME Selectable 0.01PLC to 10PLC
PROGRAMS Provide front panel access to IEEE address, choice of engineering units or scientific notation, and digital calibration
MAXIMUM INPUT 250V peak, DC to 60Hz sine wave; 10s per minute maximum on mA ranges
MAXIMUM COMMON MODE VOLTAGE (DC to 60Hz sine wave) Electrometer, 500V peak
ISOLATION (Meter COMMON to chassis) Typically 10 10 Ω in parallel with 500pF.
INPUT CONNECTOR Three lug triaxial on rear panel.
2V ANALOG OUTPUT 2V for full range input. Inverting in Amps and Coulombs mode. Output impedance 10kΩ.
PREAMP OUTPUT Provides a guard output for Volts mea sure ments. Can be used as an inverting output or with external feedback in Amps and Coulombs modes.
DIGITAL INTERFACE Handler Interface Start of test, end of test, 3 category bits.
Digital I/O 1 Trigger input, 4 outputs with 500mA sink capability.
Connector 9 pin D subminiature, male pins.
EMC Conforms with European Union Directive 89/336/EEC EN55011, EN50082-1, EN61000-3-2, EN61000-3-3, FCC part 15 class B.
SAFETY Conforms with European Union Directive 73/23/EEC EN61010-1.
GUARD Switchable voltage and ohm guard available.
TRIGGER LINE Available, see manual for usage.
READING STORAGE 2500 readings
READING RATE To internal buffer 1200 readings/second
To IEEE-488 bus 500 readings/second
To front panel 17 readings/second at 60Hz
15 readings/second at 50Hz
Notes
  1. 0.01PLC, digital filters off, front panel off, auto zero off
  2. 1.00PLC, digital filters off
  3. Binary transfer mode
DIGITAL FILTER Median and averaging (selectable from 2 to 100 readings)
DAMPING User selectable on Amps function
ENVIRONMENT Operating 0°–50°C; relative humidity 70% non-condensing, up to 35°C.
Storage –25° to +65°C
WARM-UP 1 hour to rated accuracy (see manual for recommended procedure)
POWER 90–125V or 210–250V, 50–60Hz, 60VA
PHYSICAL Case Dimensions 90mm high × 214mm wide × 369mm deep (3½ in. × 8 3 / 8 in. × 14 9 / 16 in.).
Working Dimensions From front of case to rear including power cord and IEEE-488 connector: 15.5 inches.
Net Weight <4.6kg (<10.1 lbs)
Shipping Weight <9.5kg (<21 lbs)

 

IEEE-488 BUS IMPLEMENTATION
MULTILINE COMMANDS DCL, LLO, SDC, GET, GTL, UNT, UNL, SPE, SPD
IMPLEMENTATION SCPI (IEEE-488.2, SCPI-1996.0); DDC (IEEE-488.1)
UNILINE COMMANDS IFC, REN, EOI, SRQ, ATN
INTERFACE FUNCTIONS SH1, AH1, T5, TE0, L4, LE0, SR1, RL1, PP0, DC1, DT1, C0, E1
PROGRAMMABLE PARAMETERS Function, Range, Zero Check, Zero Correct, EOI (DDC mode only), Trigger, Terminator (DDC mode only), Data Storage 2500 Storage, Calibration (SCPI mode only), Display Format, SRQ, REL, Output Format, Guard, V-offset Cal, I-offset Cal.
ADDRESS MODES TALK ONLY and ADDRESSABLE
LANGUAGE EMULATION 6512, 617, 617-HIQ emulation via DDC mode
TRIGGER TO READING DONE 150ms typical, with external trigger.
RS-232 IMPLEMENTATION Supports SCPI 1996.0
Baud Rates 300, 600, 1200, 2400, 4800, 9600, 19.2k, 38.4k, 57.6k
Protocols Xon/Xoff, 7 or 8 bit ASCII, parity-odd/even/none
Connector DB-9 TXD/RXD/GND.

 

VOLTS
Range 5½-Digit
Resolution
Accuracy
(1 Year)
18°–28°C
±(%rdg+counts)
Temperature
Coefficient
0°–18°C & 28°–50°C
±(%rdg+counts)/°C
2 V 10 µV 0.025 + 4 0.003 + 2
20 V 10 µV 0.025 + 3 0.002 + 1
200 V 1 mV 0.06 + 3 0.002 + 1
NOTES When properly zeroed, 5½-digit. Rate: Slow (100ms integration time).
NMRR 60dB on 2V, 20V, >55dB on 200V, at 50Hz or 60Hz ±0.1%
CMRR >120dB at DC, 50Hz or 60Hz
INPUT IMPEDANCE >200TO in parallel with 20pF, <2pF guarded (10MΩ with zero check on).
SMALL SIGNAL BANDWIDTH AT PREAMP OUTPUT Typically 100kHz (–3dB)

 

AMPS
Range 5½-Digit
Resolution
Accuracy
(1 Year)
18°–28°C
±(%rdg+counts)
Temperature
Coefficient
0°–18°C & 28°–50°C
±(%rdg+counts)/°C
20 pA 100 aA 1 + 30 0.1 + 5
200 pA 1 fA 1 + 5 0.1 + 1
2 nA 10 fA 0.2 + 30 0.1 + 2
20 nA 100 fA 0.2 + 5 0.03 + 1
200 nA 1 pA 0.2 + 5 0.03 + 1
2 µA 10 pA 0.1 + 10 0.005 + 2
20 µA 100 pA 0.1 + 5 0.005 + 1
200 µA 1 nA 0.1 + 5 0.005 + 1
2 mA 10 nA 0.1 + 10 0.008 + 2
20 mA 100 nA 0.1 + 5 0.008 + 1
NOTES
  1. When properly zeroed, 5½-digit. Rate: Slow (100ms integration time).
  2. aA =10 –18 A, fA=10 –15 A
INPUT BIAS CURRENT <3fA at T CAL (user adjustable). Temperature coefficient = 0.5fA/°C
INPUT BIAS CURRENT NOISE <750aA p-p (capped input), 0.1Hz to 10Hz bandwidth, damping on. Digital filter = 40 readings.
INPUT VOLTAGE BURDEN at T CAL ±1°C (user adjustable) ><20µV on 20pA, 2nA, 20nA, 2µA, 20µA ranges.
<100µV on 200pA, 200nA, 200µA ranges.
<2mV on 2mA range.
<4mV on 20mA range.
TEMPERATURE COEFFICIENT OF INPUT VOLTAGE BURDEN <10µV/°C on pA, nA, µA ranges
PREAMP SETTLING TIME (to 10% of final value) 2.5s typical on pA ranges, damping off, 3s typical on pA ranges damping on, 15ms on nA ranges, 5ms on µA and mA ranges.
NMRR >95dB on pA, 60dB on nA, µA, and mA ranges at 50Hz or 60Hz ±0.1%. Digital Filter = 40

 

AMPS
Range 5½-Digit
Resolution
Accuracy
(1 Year)
18°–28°C
±(%rdg+counts)
Temperature
Coefficient
0°–18°C & 28°–50°C
±(%rdg+counts)/°C
Test
Current
(nominal)
2 kΩ 10 mΩ 0.20 + 10 0.01 + 2 0.9 mA
20 kΩ 100 mΩ 0.15 + 3 0.01 + 1 0.9 mA
200 kΩ 1 Ω 0.25 + 3 0.01 + 1 0.9 mA
2 MΩ 10 Ω 0.25 + 4 0.02 + 2 0.9 µA
20 MΩ 100 Ω 0.25 + 3 0.02 + 1 0.9 µA
200 MΩ 1 kΩ 0.30 + 3 0.02 + 1 0.9 µA
2 GΩ 10 kΩ 1.5 + 4 0.04 + 2 0.9 nA
20 GΩ 100 kΩ 1.5 + 3 0.04 + 1 0.9 nA
200 GΩ 1 MΩ 1.5 + 3 0.04 + 1 0.9 nA
NOTES
  1. When properly zeroed, 5½-digit. Rate: Slow (100ms integration time)
MAXIMUM OPEN CIRCUIT VOLTAGE 250V DC
PREAMP SETTLING TIME (To 10% of final reading with <100pF input capacitance) 2kΩ through 200kΩ: 2ms; 20MΩ through 200MΩ: 90ms. 2GΩ through 200GΩ: 1s.

 

COULOMBS
Range 6½-Digit
Resolution
Accuracy
(1 Year)
18°–28°C
±(%rdg+counts)
Temperature
Coefficient
0°–18°C & 28°–50°C
±(%rdg+counts)/°C
20 nC 10 fC 0.4 + 50 0.04 + 10
200 nC 100 fC 0.4 + 50 0.04 + 10
2 µC 1 pC 1 + 50 0.05 + 10
20 µC 10 pC 1 + 50 0.05 + 10
NOTES
  1. Charge acquisition time must be <1000s, derate 2% for each additional 10,000s
  2. When properly zeroed, 6½-digit. Rate: Slow (100ms integration time)
INPUT BIAS CURRENT <4fA at T CAL . Temperature coefficient = 0.5fA/°C

OPTIONAL ACCESSORIES:

  • Model 237-TRX-BAR 3-Lug Triax Female-to-Female (Barrel) Adapter (for Triax Interconnect)
  • Model 4288-1 Single, Fixed Rack Mount Kit (for Models 428, 486, 487, 776, 2700, 2000 Series, 2182, 2300 Series, 2400 Series, 2500 Series, 6514, 6517A, 7001, 6430, 6485)
  • Model 4288-2 Dual, Fixed Rack Mount Kit (for Models 428, 486, 487, 776, 2000 Series, 2182, 2300 Series, 2400 Series, 6514, 6517A, 7001, 2700, 6430, 6485)
  • Model 4288-4 Fixed Rack Mount Kit (for Models 195A, 196, 220, 224, 230, 230-1, 263, 428, 486, 487, 595, 617, 740, 775A, 776, 2000 Series, 2182, 2300 Series, 2400 Series, 6512, 6514, 6517A, 7001)
  • Model 4288-5 Fixed Rack Mount Kit (for Models 428, 486, 487, 2000 Series, 2182, 2300 Series, 2400 Series, 6514, 6517A, 7001)
  • Model 4288-7 Rear Rack Mount Support Kit (for Model 2750)
  • Model 6517-ILC-3 4-Pin Interlock Cable, 1m (3.3ft) (for Models 6517A, 8009)
  • Model 7009-5 Shielded RS-232 Cable, 1.5m (5ft) (for Models 2000, 2010, 6517A, 6517B, Series 2400)
  • Model 7078-TRX-10 Low-Noise Triax Cable, 3m (10ft) (for Models 236, 237, 238, 6514, 6517A, 6517B, 7072)
  • Model 7078-TRX-20 Low-Noise Triax Cable, 6.1m (20ft) (for Models 236, 237, 238, 6514, 6517A, 6517B, 7072)
  • Model 7078-TRX-BNC 3-Slot Male Triax to BNC Adapter (for Models 486, 487, 4801, 6514, 6517B, 7072, 7072-HV)
  • Model 8009 Resistivity Test Chamber (for Models 6517A, 6517B)
  • Model 8501-1 Trigger Link Cable, DIN-to-DIN, 1m (3.3ft) (for Models 6517A, 6517B, Series 2400, KPC-TM, Trigger Link Inputs)
  • Model 8501-2 Trigger Link Cable, DIN-to-DIN, 2m (6.6ft) (for Models 6517A, 6517B, Series 2400, KPC-TM, Trigger Link Inputs)
  • Model 8503 Trigger Link Cable, DIN-to-Dual BNC, 1m (3.3ft) (for Models 2000, 2010, Series 2400, 6517A, 6517B, Trigger Link Inputs)
  • Model 8607 1kV, 2-Wire, Source Banana Test Cables, 1m (3.3ft) (for Models 2410, 6430, 6514, 6517B)
  • Model 7007-1 Double Shielded, Premium GPIB Interface Cable, 1m (3.3ft) (for GPIB Interconnect)
  • Model 7007-2 Double Shielded, Premium GPIB Interface Cable, 2m (6.6ft) (for GPIB Interconnect)
  • Model 7007-4 Double Shielded, Premium GPIB Interface Cable, 4m (13ft) (for GPIB Interconnect)
  • Model KPCI-488LPA IEEE-488.2 Interface Board for the PCI Bus

SUPPLIED ACCESSORIES:

  • Model 7078-TRX-3 Low-Noise Triax Cable, 0.9m (3ft) (for Models 236, 237, 238, 6514, 6517A, 6517B, 7072)
  • Model 8607 1kV, 2-Wire, Source Banana Test Cables, 1m (3.3ft) (for Models 2410, 6430, 6514, 6517B)
  • Model CAP-31 Protective Shield/Cap (for 3-Lug Triax Connectors)