NXP Semiconductors UM10480 User manual

UM10480
Variable gain amplifier BGA7210
Rev. 2 — 26 July 2011 User manual
Document information
Info Content
Keywords BGA7210, VGA, variable gain amplifier
Abstract This user manual describes how to evaluate the variable gain amplifier
BGA7210 using a customer evaluation kit

UM10480 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2011. All rights reserved.
User manual Rev. 2 — 26 July 2011 2 of 13
Contact information
For more information, please visit: http://www.nxp.com
For sales office addresses, please send an email to: [email protected]
NXP Semiconductors UM10480
Variable gain amplifier BGA7210
Revision history
Rev Date Description
v.2 20110726 •Section 1 “Introduction”text altered.
•Section 5 “Controlling the customer RF evaluation board”amended to include Section
5.1 “Improving linearity”
v.1 20110520 first version

UM10480 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2011. All rights reserved.
User manual Rev. 2 — 26 July 2011 3 of 13
NXP Semiconductors UM10480
Variable gain amplifier BGA7210
1. Introduction
The BGA7210 customer evaluation kit enables the user to evaluate the performance of
the variable gain amplifier BGA7210.
The BGA7210 performance information is available in the BGA7210 data sheet.
2. Quick start
1. Connect the interface board to the RF evaluation board using the flat cable.
2. Power the RF evaluation board with a 5 V, 1 W power supply.
3. Insert the interface board in a free USB slot.
4. Insert the USB flash drive in another free USB slot.
5. Launch the customer software bga7210_mswin.exe from the USB flash drive.
3. Installation
Remark: Do not change the jumper settings until you are familiar with the functions. The
jumpers are intended for evaluating the current on each supply pin. If configured correctly
the VGA can be powered by the USB bus, however RF performance might be
compromised. See Section 7 “Jumpers and connectors” on page 10.
Fig 1. BGA7210 customer evaluation kit parts
019aac406
USB interface boardflat cableRF evaluation boardcalibration port RF in
RF out GND
V
supply
jumpers
BGA7210
connectorcalibration port

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User manual Rev. 2 — 26 July 2011 4 of 13
NXP Semiconductors UM10480
Variable gain amplifier BGA7210
4. Customer evaluation kit contents
The evaluation kit contains the following items:
•ESD safe casing
•RF evaluation board
•USB interface board
•Flat cable
•USB flash drive containing:
–This user manual
–Customer software bga7210_mswin.exe
–BGA7210 data sheet

UM10480 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2011. All rights reserved.
User manual Rev. 2 — 26 July 2011 5 of 13
NXP Semiconductors UM10480
Variable gain amplifier BGA7210
5. Controlling the customer RF evaluation board
5.1 Improving linearity
The RF evaluation board is configured without using a shunt capacitor on the output.
Adding a shunt capacitor improves linearity around 2.8 GHz. For other operating
frequencies it is recommended not to add a shunt capacitor. Please refer to the Data
Sheet for performance information.
Place a shunt capacitor of 0.68 pF at a distance of 5.3 mm from the BGA7210 RF_OUT
pin, see Figure 2.
Fig 2. BGA7210 RF evaluation board PCB layout
aaa-000268

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User manual Rev. 2 — 26 July 2011 6 of 13
NXP Semiconductors UM10480
Variable gain amplifier BGA7210
5.2 Quick tour
The customer software offers advanced features for controlling the current and
attenuation of the BGA7210. The software also provides a tick box for saving power and a
tick box for automatically selecting the optimal current per attenuation setting, yielding
maximum linearity.
5.3 Setting current
The current to each amplifier can be set either automatically or manually.
•Automatically: depending on the attenuator setting, each amplifier current setting is
selected automatically. This mode optimizes current consumption without
compromising linearity
•Manually: each amplifier current can be set manually
5.4 Setting attenuation
There are three methods available for setting attenuation in the range 0 dB to 31.5 dB
using:
•the attenuator entry
•attenuation slider
•0.5 dB step button
5.5 Power save
In Power save mode, the RF blocks are switched off but it is still possible to communicate
with the chip.
Fig 3. User interface
019aac407
increase attenuation
attenuation slider
decrease attenuation
power save mode
attenuation entryamplifier 2 currentamplifier 1 current
set optimal currents device versionUSB statuswrite status

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User manual Rev. 2 — 26 July 2011 7 of 13
NXP Semiconductors UM10480
Variable gain amplifier BGA7210
6. BGA7210 evaluation
Remark: The RF evaluation board output is configured with a shunt capacitor to yield
optimal linearity at approximately 2 GHz. It is recommended that the shunt capacitor is
removed at other operating frequencies. Please refer to the BGA7210 data sheet for
performance information.
6.1 Calibration
The calibration port can be used to determine the PCB losses.
6.2 S-parameters and output compression point
Both S-parameters and the output compression point (P1 dB) are measured with a
NetWork Analyzer (NWA); see Figure 4.
The P1 dB is measured by sweeping the input power, and observing where the S21 of the
device is compressed by 1 dB compared to the linear gain. In order for this measurement
to accurately measure the input power, the input must first be calibrated with a power
head. The output power of the device is calculated using equation Equation 1.
(1)
The drive power can be optionally enhanced with a driver amplifier. To prevent the output
signal driving the NWA receiver into compression, an attenuator can be inserted at the
NWA input. Both driver amplifier and attenuator should be included in the calibration path.
In order to maintain small signal conditions for the S-parameter measurements, an input
power of 20 dBm is applied.
Fig 4. S-parameter and output compression power set-up
Pout dBmPin dBms21 dB+=
019aac408
OPTIONAL
PRE-AMPLIFIER
POWER
SUPPLY
MMIC
DUT
PORT 1 PORT 2
2 PORT (or 4 PORT) NETWORK ANALYZER
OPTIONAL
ATTENUATOR

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User manual Rev. 2 — 26 July 2011 8 of 13
NXP Semiconductors UM10480
Variable gain amplifier BGA7210
6.3 Output third-order intercept point
The output intercept point (OIP3) is a figure of merit for linearity; see Figure 5. The set-up
is configured to achieve an accurate measurement of the OIP3; see Figure 6. After the
signal generators, a Low-Pass Filter (LPF) and isolator is applied, before combining the
two signals. This configuration gives best isolation between the generators, hence IMD3
levels of the input signal < 80 dBc can be measured.
Please refer to the BGA7210 data sheet for power level and tone spacing values.
Fig 5. Definition of output intercept point (OIP3)
019aac409
2*f1-f2f1f2f2*f2-f1
IMD3
output
power
dBc
dBc
fundamental
slope 1:1
saturation
region
IMD3
slope 1:3
IP3
input power
Fig 6. Output intercept point (OIP3) set-up
019aac410
POWER
SUPPLY
MMIC
DUT
SIGNAL
GENERATOR
SIGNAL
GENERATOR
ISOLATOR
LOW-PASS
FILTER (LPF)
POWER
COMBINER SPECTRUM
ANALYZER
ISOLATOR
LOW-PASS
FILTER (LPF)

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User manual Rev. 2 — 26 July 2011 9 of 13
NXP Semiconductors UM10480
Variable gain amplifier BGA7210
6.4 Noise
The Noise Figure (NF) is measured using a calibrated noise source with a specified
Excess Noise Ratio (ENR), and a spectrum analyzer with a noise measurement option.
The system is calibrated with this noise source in order to measure accurate noise figures;
see Figure 7.
Fig 7. Noise figure measurement set-up
019aac411
POWER
SUPPLY
MMIC
DUT
NOISE
SOURCE
SPECTRUM
ANALYZER
including
NOISE OPTION

UM10480 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2011. All rights reserved.
User manual Rev. 2 — 26 July 2011 10 of 13
NXP Semiconductors UM10480
Variable gain amplifier BGA7210
7. Jumpers and connectors
The RF evaluation board is powered through connector X4. The X3 jumpers are set as
shown in Figure 9.
Fig 8. BGA7210 RF evaluation board jumpers and connectors
Table 1. RF evaluation board components
Component reference Description
RF connectors
X6, X7 calibration port for determining PCB losses
X1 RF in
X5 RF out
Control interface
X2 USB interface board connector
Voltage supply
X4 external supply voltage 5 V/200 mA
X3 power configuration jumper
019aac412