RF3330PCBA-41X データシートの表示（PDF） - RF Micro Devices

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RF3330PCBA-41X

IF GAIN CONTROLLED AMPLIFIER

RF Micro Devices 

RF3330

Evaluation Test Procedure

Introduction

The RF3330 is an IF amplifier with AGC, designed for use in Cable Television applications. Voltage gain is varied using an ana-

log voltage control signal. The differential input is high impedance (2000Ω) and the differential output is low impedance

(10Ω). The 3dB bandwidth is 150MHz and has a maximum voltage gain of 34dB and a minimum voltage gain of 8dB. The

AGC Control Voltage ranges from 0.5V for minimum gain to 3.3V for maximum gain. The device is packaged in the SOT23-8,

which minimizes board area.

Evaluation Board

The 3330410 board has been designed to achieve maximum versatility for device evaluation. The board is designed for either

a differential or single-ended input signal. Likewise, the output can be either singly or differentially loaded. There is also a sep-

arate VCC and AGC voltage pin. For constant maximum gain applications, the VCC and AGC pins can be tied together.

Input

For differential operation on the input, the J1 connector (VIN unbalanced) is not required. Differential voltages are applied

directly through connectors J2 and J3 (VIN balanced). DC blocking capacitors are also provided to protect equipment or

upstream components. Boards ordered from RF Micro Devices are assembled in this configuration.

Single-ended operation on the input can be accomplished in two ways. The first option uses the differential board setup as

described above, with the addition of an external low frequency 180° power combiner. The combiner splits the single input sig-

nal into two signals with inverted phase. The second option for single-ended operation utilizes a SAW filter which converts from

double to single-ended. The current evaluation board has an option to insert a SAW filter on the input. For this setup, the J1

connector (VIN unbalanced) would be utilized. The 3330410 board has been evaluated using a 44MHz Siemens+Matsushita

filter. This is a common IF frequency used in cable modem applications.

Table 1. SAW Filters

EPCOS P/N

X6857D

X6966M

X6964D

X6855M

X6866D

X6965M

FC (MHz)

36.000

36.125

43.750

44.000

44.000

44.000

Output

For differential operation on the output, the optional C4, C5, R1, and R5 would be inserted and the T1 transformer would be

removed. The J4 (VOUT unbalanced) and J5 (VOUT balanced) connectors would be uses as differential outputs.

For single-ended operation on the output, only the J4 connector (VOUT unbalanced) is used and only one analyzer is necessary.

There is a 1:1 transformer to convert the unbalanced output to a balanced signal. The amplifier is designed to drive a 1000Ω

load. Driving a 50Ω load, presented by the spectrum analyzer will cause the amplifier to saturate. In order to present a 1000Ω

load to the amplifier a resistive matching circuit is on the board. Boards ordered from RF Micro Devices are assembled in this

configuration.

Test Setup Calibration

Because of the fact that the impedances of the amplifier are not 50Ω, there are some special considerations when calibrating

a test setup.The evaluation test setup is shown in Figure 1.

Input

As stated previously, the balanced input impedance of the RF3330 is 2000Ω. The signal generator used has an unbalanced

50Ω source, and is typically used in unbalanced 50Ω impedance systems. Due to this load mismatch, a positive amplitude

Rev A4 DS060908

7628 Thorndike Road, Greensboro, NC 27409-9421 · For sales or technical

support, contact RFMD at (+1) 336-678-5570 or sales-support@rfmd.com.

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