ADA4530-1R-EBZ User Guide

UG-865

Rev. 0 | Page 3 of 14

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

JP3

Description

Unconnected

Triax guard is externally driven. This

configuration is used when 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.

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.

GUARD RING

GUARD VIA FENCE

Figure 3. Guarding