Data Sheet

ADA4961

Rev. C | Page 17 of 24

APPLICATIONS INFORMATION

BASIC CONNECTIONS

Figure 40 shows the basic connections for operating the

ADA4961. Apply a voltage between 3.3 V and 5.0 V to the

VCCx pins. Decouple each supply pin with at least one low

inductance, surface-mount ceramic capacitor of 0.1 μF, placed

as close as possible to the device.

The outputs of the ADA4961 must be pulled up to the positive

supply with 0.5 μH RF chokes. The differential outputs are

biased to the positive supply and require ac coupling capacitors,

preferably 0.1 μF. Similarly, the input pins require ac coupling

because they are at bias voltages of about 1 V above ground. The

ac coupling capacitors and the RF chokes are the principle

limitations for operation at low frequencies.

The digital pins (mode control pins, associated SPI and parallel

gain control pins, PM, and PWUP) operate at a voltage of 3.3 V.

To enable the ADA4961, the PWUP pin must be pulled to a

logic high. Pulling PWUP low puts the ADA4961 in sleep mode,

reducing current consumption to approximately 7 mA at

ambient temperature.

0dB TO 21dB

ATTEN

EXPOSED

PAD

2

3

18

14

15

17

16

4

5

1

7

8

9

10

11

24

23

22

21

20

19

12

13

6

VIN+

VIN–

VOUT+

+5V

0.1µF

(0402)

10µF

(0603)

BALANCED 50Ω

LOAD

BALANCED 100Ω

SOURCE

VOUT–

SPI, PARALLEL INTERFACE

DNC

DNC

DNC

GND

+15dB

ADA4961

NOTES

1. DNC = DO NOT CONNECT. DO NOT CONNECT TO THIS PIN.

Figure 40. Basic Connections

Table 10. Basic Connections

Pin No.

Mnemonic

Description

Basic Connection

5 V Power

21

VCC1

Amplifier core power

supply

Connect these pins to 5 V and decouple to GND using 10 μF and 0.1 μF

capacitors close to the pins.

22

VCC2

23

VCC3

24

VCC4

GND

1, 4, 5

GND

Ground pins

Connect to ground.

RF Inputs

2

VIN+

Differential RF inputs,

differential input

impedance is 100 Ω

Connect these pins to the balanced output of the previous device in the signal

chain. A balun can be used to convert from a single-ended signal to differential

or to improve even order distortion if the previous device in the signal chain is

differential.

3

VIN−

RF Outputs

17

VOUT+

Differential RF inputs,

differential output

impedance is 50 Ω

Connect these pins to the balanced input of the next device in the signal chain.

A balun can be used to convert from the ADA4961 differential output to a

single-ended signal or to improve even order distortion if the next device in the

signal chain is differential.

16

VOUT−