ANALOG DEVICES ADA4530-1 Evaluation Board User Guide

DEVICES ADA4530-1 Evaluation Board
User Guide

EVALUATION BOARD PHOTOGRAPHS

FEATURES
► Footprint for ADA4530-1 8-lead SOIC package
► Footprints for passive components
► Available in buffer or transimpedance configuration
► Easy modifications to other standard configurations
► Guard ring to minimize leakage current
► Assembled with metal shields
► Enables quick prototyping
► Easy connection to test equipment

GENERAL DESCRIPTION

The ADA4530-1R-EBZ is an evaluation board for the ADA4530-1 offered in an 8-lead SOIC package. The ADA4530-1R-EBZ is a 4-layer printed circuit board (PCB) designed to minimize leakage currents with its guard ring features for femtoampere input bias current (I ) measurement.
The ADA4530-1R-EBZ is available in two default configu- B rations: buffer (ADA4530-1R-EBZ-BUF) and transimpedance (ADA4530-1R-EBZ-TIA). Both boards are populated with the necessary passive components, banana jacks/terminal blocks for supply voltages, BNC/terminal blocks for the output voltage, multiple test pins, and metal shields. All components are placed on the primary side with the exception of the triaxial (triax)/coaxial (coax) input connector (J1) and SHIELD3.
The ADA4530-1R-EBZ also has unpopulated resistor and capacitor pads that allows quick prototyping with different configurations, such as noninverting gain and inverting gain.
Specifications for the ADA4530-1 are provided in the ADA4530-1 data sheet available from Analog Devices, Inc. The ADA4530-1 data sheet and the AN-1373 Application Note should be consulted in conjunction with this user guide when using the evaluation board.
Figure 1 shows the top view of the evaluation board, and Figure 2 shows the bottom view. For more views of the evaluation board images, see the ADA4530 -1R-EBZ Evaluation Board Photographs section.
PLEASE SEE THE LAST PAGE FOR AN IMPORTANT WARNING AND LEGAL TERMS AND CONDITIONS.

HARDWARE COMPONENTS

BOARD ASSEMBLY
The ADA4530-1R-EBZ evaluation board is available in two default configurations:
► ADA4530-1R-EBZ-BUF: amplifier is populated in buffer configuration
► ADA4530-1R-EBZ-TIA: amplifier is populated in transimpedance configuration
Both evaluation boards are pre-assembled with necessary components, except for SHIELD2. SHIELD2 is included in the kit, but not installed.
See the Amplifier Configurations section for all other possible configurations.
INPUT, OUTPUT, AND SUPPLIES
ADA4530-1R-EBZ-TIA is populated with an input BNC connector (J1) that connects to the amplifier inverting pin through JP2. ADA4530-1R-EBZ-BUF is populated with an input triax connector (J1). The inner conductor of J1 is the high impedance connection through JP1 to the noninverting pin of the ADA4530-1. The inner braided shield is a guard; the driving source is configured with JP3. The outer braided shield is the signal return; it is connected to GND.
The evaluation board uses JP3 to select the driving source of the triax guard. Table 1 shows the three different configurations of JP3.
Table 1. JP3 Configuration

the guard is driven by an external test equipment, such as a picoammeter. This configuration is also by default on both the ADA4530-1R-EBZ-TIA and ADA4530 -1R-EBZ-BUF boards.
---|---
Short
TRIAX GUARD to AMP GUARD| Triax guard is driven by the ADA4530-1 guard buffer.
This configuration is useful if the ADA4530-1R-EBZ-BUF is connected to a passive sensor.
Short
TRIAX GUARD to GND| Triax guard is connected to signal ground. This configuration is useful when the amplifier is in transimpedance configuration with the noninverting pin connected to signal ground.

The evaluation board output can be measured with two different options:

1. BNC connector (J2) allows BNC cabling
2.  Terminal block (J7) allows wire-to-board connection A VOUT_TP test point is also provided.R isolates the output load from the amplifier output to prevent any oscillation from excessive capacitive loading. A 499 Ω resistor is mounted on-board.
   Power supplies to the board can be applied in two different ways:
   1. V+ (J3), GND (J4), and V− (J5) allow banana plugs to be used
   2. Terminal block (J6) allows wire-to-board connection V+_TP, GND_TP, and V−_TP test points are provided.

GUARD AND SHIELD
The ADA4530-1R-EBZ board uses guard rings, a guard plane, and a via fence to entirely guard the high impedance input traces against leakage current. On the top layer, the guard ring encircle the inverting and noninverting input components (see Figure 3).
Guard via fences from the top layer to bottom layer are also used to encircle the high impedance inputs to prevent leakage currents from inner layers of the board. For more information on the physical implementation of guarding techniques, see the ADA4530-1 data sheet.
The copper shield traces, SHIELD1, SHIELD2, and SHIELD3 allow soldered metal shields to enclose the high impedance inputs as a means to avoid electrostatic interference. The shield traces are electrically connected to the amplifier guard potential.
SHIELD1 and SHIELD3 are 1 inch × 1.5 inch × 0.25 inch metal shields and are pre-assembled on board. There is a high impedance pin socket (P7) that goes through the bottom of the board, and hence SHIELD3 is populated at the bottom of the board. Other than providing electrostatic shielding, the shields also prevent contamination from fingerprints, dust, and other contaminants to the high impedance inputs.
SHIELD2 is a 1.5 inch × 3 inch × 0.75 inch metal shield and is provided separately with the evaluation board. It is used when large through hole resistors are populated on board. RF clips are assembled to hold the shield in place. Note that it is sufficient to remove the SHIELD1 cover, without needing to desolder SHIELD1, to accommodate SHIELD2 when large through hole resistors are used.

HARDWARE COMPONENTS
BOARD LAYERS STACKUP The ADA4530-1R-EBZ is a 4-layer evaluation board that uses the Rogers 4350B, a high performance PCB laminate. A hybrid stackup is required for mechanical strength. The top and bottom layers are ceramic (Rogers 4350B) while the middle core layer is a conventional glass epoxy laminate (FR-4). The Rogers 4350B material provides superior insulation resistance in the presence of humidity compared to glass/epoxy materials. It minimizes current leakage and, therefore, increases signal integrity. Additionally, the dielectric relaxation times of Rogers 4350B are much shorter than glass/epoxy dielectrics. For more information on dielectric relaxation, see the ADA4530-1 data sheet.

CLEANING AND HANDLING

It is important to always handle the board by the edges and never touch the area within SHIELD1.
Before using the board, properly clean the evaluation board to remove any contaminants, such as solder flux, saline moisture, dirt, and dust, to maintain its low leakage performance. Any contaminants can severely degrade its femtoampere performance.
The board must also be cleaned again after any rework to the components.
An effective cleaning procedure consists of the following steps:

1. Boil the solvent. Add the solvent (n-Propyl Bromide) to the vapor degreaser and set the boiling temperature. The temperature varies based on the solvent used.
2. Activate the degreaser. Turn on the degreaser to activate the cooling coils as well as the heating element that boils the solvent. The cooling coils above the heating elements ensure that a vaporized solvent remains trapped in a vapor zone inside the degreaser instead of rising and escaping.
3.  Prepare the boards to be cleaned. Place parts to be cleaned in a stainless steel mesh basket in vertical position to ensure wetting of all surfaces, optimum cleaning action, and good drainage.
4. Place the boards to be cleaned in the degreaser. Slowly lower the mesh basket below the vapor zone above the boiling sump, suspend, and hold in place until condensation ceases for 5 minutes. The solvent vapor condenses on the parts, eating away at grease  nd dirt. Cover the tank during cleaning process to minimize vapor loss.
5.  Spray the top and bottom sides of the board for 30 secs each. When spraying, keep the spray nozzle in the vapor zone area and spray below the cooling coils and above the boiling sump.
6. Remove the boards slowly out of the vapor zone.
7. Dry the boards. Use compressed dry air (CDA) to dry the board. Blow air around the U1 pins, the input traces to J1, and the guard ring area. Be sure to direct the compressed air under J1 and U1 as well.
8. Bake the boards (optional). To ensure that the board is completely dry, bake the board in the oven at 125°C for 15 minutes.
9. After cleaning, place the cover of the metal shield on both sides of the board. The metal shields help prevent any contact to the guarded area.

AMPLIFIER CONFIGURATIONS

This section describes the different configurations possible with the evaluation board. For some configurations, remove stated preassembled components to allow assembly of new components of choice.
After any rework, the evaluation board must be cleaned according to the Cleaning and Handling section.
BUFFER WITH TRIAX GUARD EXTERNALLY
DRIVEN (ADA4530-1R-EBZ-BUF)
The amplifier on this evaluation board is defaulted to a buffer configuration. An input signal can be applied through the triax connector, J1. Note that JP3 is left unconnected by default so that the triax guard can to be driven by external test equipment. For  irect input bias current (I ) measurement, connect an electrometer such as the Keithley 6430 to the board via J1. The Keithley 6430 internal guard buffer drives the triax guard (see Figure 5 and Figure 6 for the configuration). Details regarding I B measurement are described in the AN-1373 Application Note.
Table 2. Buffer with Triax Guard Externally Driven Pad/Connector Configuration

BUFFER WITH TRIAX GUARD DRIVEN BY AMP GUARD
For a buffer configuration where the triax guard is not driven by any external test equipment, TRIAX GUARD must be shorted to AMP GUARD via JP3. This configuration is useful when the buffer is connected to a passive sensor (or an input signal).
Table 3 shows the recommended component values.
Table 3. Buffer with Triax Guard Driven by Amp Guard Pad/Connector Configuration

BUFFER WITH RESISTOR AT IN+ TO GROUND
To configure the DUT as a buffer with a large resistor at the nonin- verting pin to ground, use the ADA4530-1R-EBZ-BUF evaluation board and remove JP1. Large value, through hole resistors (RS2) can be placed between the noninverting pin and ground using the P7 and P4 pin sockets. Place one end of the leaded resistor at P7 and the other end at P4 (GND). If an SMT resistor is used, use the RS1 pad instead. The R pad allows the assembly of a 1206 or 1210 package size resistor. This configuration allows the user to measure I B+ , where V OUT = I S1 B+ × RS1 or V OUT = I B+ × RS2.
Table 4. Buffer with Resistor at IN+ to Ground Pad Configuration 1

Use the ADA4530-1R-EBZ-BUF board.
Assemble either RS1 or RS2. NONINVERTING GAIN
To configure the ADA4530-1 in a noninverting gain, use the components shown in Table 5. Choose appropriate RF1 and RS3 values for the desired gain. Note that the pre-assembled RF1 must be replaced with a resistor of choice.
Table 5. Noninverting Gain Pad/Connector Configuration1

Use the ADA4530-1R-EBZ-BUF board.

AMPLIFIER CONFIGURATIONS
TRANSIMPEDANCE WITH 10 GΩ SMT FEEDBACK RESISTOR AND IN+ CONNECTED TO GROUND (ADA4530-1R-EBZ-TIA)
On the ADA4530-1R-EBZ-TIA board, the amplifier is defaulted to a transimpedance configuration. The transimpedance configuration is a current- to-voltage (I to V) converter. A 10 GΩ SMT 1206 package size feedback resistor (RF1) is pre-assembled on board. If other resistor values or package sizes are needed, the 10 GΩ feedback resistor can be desoldered to allow the assembly for the SMT esistor of choice. The evaluation board provides a combination footprint that allows assembly of either an 0805, 1206, 1210, 2510, or 2512 package size for RF1.
Larger value through hole feedback resistors, in the order of high gigaohms or teraohms, are also often used in a transimpedance application. This option is discussed in the Transimpedance with
Through Hole Feedback Resistor section.
Table 6. Transimpedance with 10 GΩ SMT Feedback Resistor and IN+ Connected to Ground Pad/Connector Configuration

TRANSIMPEDANCE WITH THROUGH HOLE FEEDBACK RESISTOR
In a transimpedance configuration, larger value through hole feedback resistors, in the order of high gigaohms or teraohms, are often used.
These resistors are glass encapsulated and hermetically sealed, and come in large footprints. An example of this is the Ohmite RX-1M ultrahigh resistance, high stability, hermetically sealed resistor.
To cater to its large footprint, pin sockets (P7 and VOUT) are provided for RF2. Place one end of the leaded resistor at P7 and the other end at VOUT. Note that when using the evaluation board for this configuration, use the ADA4530-1R-EBZ-TIA board and remove the pre-assembled 10 GΩ feedback resistor.
When RF2 is used, remove the cover of SHIELD1 to allow placement of the large through hole resistor.
Secure SHIELD3, which is provided with the kit, with the pre-assembled RF clips to provide electrostatic shielding.
Table 7. Transimpedance with Through Hole Feedback Resistor Pad/ Connector Configuration1

AMPLIFIER CONFIGURATIONS TRANSIMPEDANCE WITH DIRECT SENSOR CONNECTION
The ADA4530-1R-EBZ-TIA board can be reconfigured to allow direct sensor connection. The P6 and P1, P2, or P3 pins are provided to allow assembly of a photodiode. To reconfigure the board, remove the input BNC connector (J1). The user must then access Pin P6 (the inner conductor pin of the BNC connector).
Assemble the photodiode of choice between P6 and P1, P2, or P3. P1, P2, and P3 are electrically connected to signal ground. These three pins are provided to allow different photodiode packages to be used, for example: TO-19, TO-5, or TO-8.
Table 8. Transimpedance with Direct Sensor Connection Pad/Connector Configuration 1

Use the ADA4530-1R-EBZ-TIA board.
See the Photodiode Interface section in the ADA4530-1 data sheet on how to select CF1.
Assemble either RF1 or RF2. INVERTING GAIN
To configure the ADA4530-1 in an inverting gain, use the components shown in Table 9. Choose appropriate RF1 and JP2 values for the desired gain.
Table 9. Inverting Gain Pad Configuration1

AMPLIFIER CONFIGURATIONS

ADA4530-1R-EBZ EVALUATION BOARD PHOTOGRAPHS

EVALUATION BOARD SCHEMATICS

ORDERING INFORMATION
BILL OF MATERIALS
Table 10. Bill of Materials for ADA4530-1R-EBZ-TIA

Qty| Reference Designator| Description| Manufacturer Part Number| Distributor
---|---|---|---|---
1| U1| Femtoampere input bias current electrometer amplifier| Analog Devices, Inc., ADA4530-1|
---|---|---|---|---
| | (device under test)| |
2| C1, C2| 0.1 µF, 50 V, 5%, 0805| Kemet, C0805C104J5RACTU| Digi-Key, 399-1171-6-ND
2| C3, C4| 10 µF, 35 V, 10%, 7343| AVX, TPSD106K035R0125| Digi-Key, 478-3337-2-ND
1| RO| 499 Ω, 0.125 W, 1%, 0805| Panasonic, ERJ-6ENF4990V| Digi-Key, P499CCT- ND
2| RS1, JP2| 0 Ω, 0.25 W, 0.05%, 1206| Panasonic, ERJ-8GEY0R00V| Digi-Key, P0 .0ECT-ND
1| RF1| 10G Ω, 0.25W, 10%, 1206| Ohmite, HVC1206Z1008KET| Digi-Key, HVC1206Z1008KETCT-
| | | | ND
1| J1| BNC connector, right angle| Trompeter/Cinch Connectivity, UCBBJR29| Mouser, 530-UCBBJR29
1| J2| BNC connector, through hole| TE Connectivity, 1-1337445-0| Digi-Key, A101972-ND
1| JP3| 3-pin header, 100 mil spacing| Samtec, TSW-103-08-G-S| Digi-Key, SAM1038-03-ND
3| J3, J4, J5| Banana jack, panel mount| Emerson Network Power Connectivity| Digi-Key, J147-ND
| | | Johnson, 108-0740-001|
1| J6| Terminal block, 2-position| Keystone, 8718| Mouser, 534-8718
1| J7| Terminal block, 3-position| Keystone, 8719| Mouser,534-8719
3| P4, P7, VOUT| Pin receptacle, 22 mil to 32 mil pin diameter| Mill-Max, 0294-0-15-15-06-27-10-0| Digi-Key, ED90072-ND
1| SHIELD1, SHIELD3| 1.0 × 1.5 × 0.25 RF shield| Fotofab, DMP-1.0 X 1.5 X 0.25| Digi-Key, 655-1015-ND
1| SHIELD2| 1.5 × 3.0 × 0.75 RF shield| Fotofab, 1.5 X 3.0 X 0.75|
3| N/A1| RF shield clip (to be used with SHIELD2)| Harwin, Inc., S1711-46R| Digi-Key, 952-1475-1-ND

N/A means not applicable.
Table 11. Bill of Materials for ADA4530-1R-EBZ-BUF

Qty| Reference Designator| Description| Manufacturer Part Number| Distributor
---|---|---|---|---
1| U1| Femtoampere input bias current electrometer amplifier| Analog Devices, Inc., ADA4530-1|
---|---|---|---|---
| | (device under test)| |
2| C1, C2| 0.1 µF, 50 V, 5%, 0805| Kemet, C0805C104J5RACTU| Digi-Key, 399-1171-6-ND
2| C3, C4| 10 µF, 35 V, 10%, 7343| AVX, TPSD106K035R0125| Digi-Key, 478-3337-2-ND
1| RO| 499 Ω, 0.125 W, 1%, 0805| Panasonic, ERJ-6ENF4990V| Digi-Key, P499CCT- ND
3| RF1, JP1| 0 Ω, 0.25 W, 0.05%, 1206| Panasonic, ERJ-8GEY0R00V| Digi-Key, P0 .0ECT-ND
1| J1| Triax connector, right angle, 3-lug| Emerson Network Power Connectivity| Digi-Key, 1097-1046-ND
| | | Trompeter, CBBJR79/A|
1| J2| BNC connector, through hole| TE Connectivity, 1-1337445-0| Digi-Key, A101972-ND
1| JP3| 3-pin header, 100 mil spacing| Samtec TSW-103-08-G-S| Digi-Key, SAM1038-03-ND
3| J3, J4, J5| Banana jack, panel mount| Emerson Network Power Connectivity| Digi-Key, J147-ND
| | | Johnson, 108-0740-001|
1| J6| Terminal block, 2-position| Keystone, 8718| Mouser, 534-8718
1| J7| Terminal block, 3-position| Keystone, 8719| Mouser, 534-8719
3| P4, P7, VOUT| Pin receptacle, 22 mil to 32 mil pin diameter| Mill-Max, 0294-0-15-15-06-27-10-0| Digi-Key, ED90072-ND
1| SHIELD1, SHIELD3| 1.0 × 1.5 × 0.25 RF shield| Fotofab, DMP-1.0 X 1.5 X 0.25| Digi-Key, 655-1015-ND
1| SHIELD2| 1.5 × 3.0 × 0.75 RF Shield| Fotofab, 1.5 X 3.0 X 0.75|
3| N/A1| RF shield clip (to be used with SHIELD2)| Harwin, Inc., S1711-46R| Digi-Key, 952-1475-1-ND

ORDERING INFORMATION

NOTES
ESD Caution
ESD (electrostatic discharge) sensitive device. Charged devices and circuit boards can discharge without detection. Although this product features patented or proprietary protection circuitry, damage may occur on devices subjected to high energy ESD. Therefore, proper ESD precautions should be taken to avoid performance degradation or loss of functionality.
Legal Terms and Conditions
By using the evaluation board discussed herein (together with any tools, components documentation or support materials, the “Evaluation Board”), you are agreeing to be bound by the terms and conditions set forth below (“Agreement”) unless you have purchased the Evaluation Board, in which case the Analog Devices Standard Terms and Conditions of Sale shall govern. Do not use the Evaluation Board until you have read and agreed to the Agreement. Your use of the Evaluation Board shall signify your acceptance of the Agreement. This Agreement is made by and between you (“Customer”) and Analog Devices, Inc. (“ADI”), with its principal place of business at Subject to the terms and conditions of the Agreement, ADI hereby grants to Customer a free, limited, personal, temporary, non-exclusive, non-sublicensable, non-transferable license to use the Evaluation Board FOR EVALUATION PURPOSES ONLY. Customer understands and agrees that the Evaluation Board is provided for the sole and exclusive purpose referenced above, and agrees not to use the Evaluation Board for any other purpose. Furthermore, the license granted is expressly made subject to the following additional limitations: Customer shall not (i) rent, lease, display, sell, transfer, assign, sublicense, or distribute the Evaluation Board; and (ii) permit any Third Party to access the Evaluation Board. As used herein, the term “Third Party” includes any entity other than ADI, Customer, their employees, affiliates and in-house consultants. The Evaluation Board is NOT sold to Customer; all rights not expressly granted herein, including ownership of the Evaluation Board, are reserved by ADI. CONFIDENTIALITY. This Agreement and the Evaluation Board shall all be considered the confidential and proprietary information of ADI. Customer may not disclose or transfer any portion of the Evaluation Board to any other party for any reason. Upon discontinuation of use of the Evaluation Board or termination of this Agreement, Customer agrees to promptly return the Evaluation Board to ADI. ADDITIONAL RESTRICTIONS. Customer may not disassemble, decompile or reverse engineer chips on the Evaluation Board. Customer shall inform ADI of any occurred damages or any modifications or alterations it makes to the Evaluation Board, including but not limited to soldering or any other activity that affects the material content of the Evaluation Board. Modifications to the Evaluation Board must comply with applicable law, including but not limited to the RoHS Directive. TERMINATION. ADI may terminate this Agreement at any time upon giving written notice to Customer. Customer agrees to return to ADI the Evaluation Board at that time. LIMITATION OF LIABILITY. THE EVALUATION BOARD PROVIDED HEREUNDER IS PROVIDED “AS IS” AND ADI MAKES NO WARRANTIES OR REPRESENTATIONS OF ANY KIND WITH RESPECT TO IT. ADI SPECIFICALLY DISCLAIMS ANY REPRESENTATIONS, ENDORSEMENTS, GUARANTEES, OR WARRANTIES, EXPRESS OR IMPLIED, RELATED TO THE EVALUATION BOARD INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTY OF MERCHANTABILITY, TITLE, FITNESS FOR A PARTICULAR PURPOSE OR NONINFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS. IN NO EVENT WILL ADI AND ITS LICENSORS BE LIABLE FOR ANY INCIDENTAL, SPECIAL, INDIRECT, OR CONSEQUENTIAL DAMAGES RESULTING FROM CUSTOMER’S POSSESSION OR USE OF THE EVALUATION BOARD, INCLUDING BUT NOT LIMITED TO LOST PROFITS, DELAY COSTS, LABOR COSTS OR LOSS OF GOODWILL. ADI’S TOTAL LIABILITY FROM ANY AND ALL CAUSES SHALL BE LIMITED TO THE AMOUNT OF ONE HUNDRED US DOLLARS ($100.00). EXPORT. Customer agrees that it will not directly or indirectly export the Evaluation Board to another country, and that it will comply with all applicable United States federal laws and regulations relating to exports. GOVERNING LAW. This Agreement shall be governed by and construed in accordance with the substantive laws of the Commonwealth of Massachusetts (excluding conflict of law rules). Any legal action regarding this Agreement will be heard in the state or federal courts having jurisdiction in Suffolk County, Massachusetts, and Customer hereby submits to the personal jurisdiction and venue of such courts. The United Nations Convention on Contracts for the International Sale of Goods shall not apply to this Agreement and is expressly disclaimed.

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