UG-865

ADA4530-1R-EBZ User Guide

Rev. 0 | Page 6 of 14

AMPLIFIER CONFIGURATIONS

This section describes the different configurations possible with

the evaluation board. For some configurations, remove stated pre-

assembled 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.

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

Table 2. Buffer with Triax Guard Externally Driven

Pad/Connector Configuration

Pad/Connector

Description

JP1

0 Ω

JP3

Unconnected

RF1

0 Ω

RF1

0Ω

JP1

0Ω

Figure 5. Buffer with Triax Guard Externally Driven

U1

V+

RO

499Ω

RF1

0Ω

J2

(BNC)

OUTPUT

J1

(TRIAX)

INPUT

TRIAX

GUARD IS

EXTERNALLY

DRIVEN

V–

JP1

0Ω

Figure 6. Buffer with Triax Guard Externally Driven Schematic

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

Description

JP1

0 Ω

JP3

Short TRIAX GUARD to AMP GUARD

RF1

0 Ω

SHORT TRIAX GUARD

TO AMP GUARD

RF1

0Ω

JP1

0Ω

Figure 7. Buffer with Triax Guard Driven by Amp Guard

TRIAX

GUARD IS

CONNECTED TO

AMP GUARD

RO

499Ω

J2

(BNC)

OUTPUT

U1

V+

RF1

0Ω

V–

JP1

0Ω

J1

(TRIAX)

INPUT

Figure 8. Buffer with Triax Guard Driven by Amp Guard Schematic