RFMD RF2938

RF2938
2
2.4GHZ SPREAD-SPECTRUM TRANSCEIVER
Typical Applications
• Wireless LANs
• Inventory Tracking
• Wireless Local Loop
• Wireless Security
• Secure Communication Links
• Digital Cordless Telephones
Product Description
The RF2938 is a monolithic integrated circuit specifically
designed for direct-sequence spread-spectrum systems
operating in the 2.4GHz ISM band. The part includes a
direct conversion from IF receiver, quadrature demodulator, I/Q baseband amplifiers with gain control and RSSI,
on-chip programmable baseband filters, dual data comparators. For the transmit side, a QPSK modulator and
upconverter
are provided. The design reuses the IF
SAW filter for transmit and receive reducing the number
of SAW filters required. Two cell or regulated three cell
(3.6V maximum) battery applications are supported by
the part. The part is also designed to be part of a 2.4GHz
chip set consisting of the RF2444 LNA/Mixer and one of
the many RFMD high efficiency GaAs HBT PA’s and a
dual frequency synthesizer.
Optimum Technology Matching® Applied
VCC2
BW CTRL
NC
VREF 2
VCC3
DCFB Q
DCFB I
RSSI
NC
Si CMOS
VREF 1
SiGe HBT
RX VGC
GaAs MESFET
NC
üSi Bi-CMOS
GaAs HBT
48
47
46
45
44
43
42
41
40
39
38
37
36
NC
NC
2
35
NC
PD
3
34
RXQ DATA
33
Q OUT
32
RXI DATA
31
I OUT
30
VCC4
29
TXQ DATA
28
TXQ BP
27
TXI DATA
26
TXI BP
25
IF1 OUT+
RX
4
5
0.50
9.00
+ 0.10
0.22
+ 0.05
7.00
+ 0.10 sq.
4.57
+ 0.10 sq.
Exposed pad protrusion
0.0000 to 0.0127 (see note 4).
7° MAX
0° MIN
1.00
+ 0.10
Dimensions in mm
0.17 MAX.
0.60
+ 0.15
NOTES:
0.10
1. Shaded lead is Pin 1.
2. Lead coplanarity - 0.08 with respect to datum "A".
3. Leadframe material: EFTEC 64T copper or equivalent, 0.127 mm (0.005) thick.
4. Solder plating (85/15) on exposed area.
Package Style: TQFP-48 EDF, 9x9
11
• 45MHz to 500MHz IF Quad Demod
1
TX EN
-A-
Features
NC
RX EN
0.10
0.00
TRANSCEIVERS
Si BJT
9.00
+ 0.20
• On-Chip Variable Baseband Filters
• Quadrature Modulator and Upconverter
• 2.7V to 3.6V Operation
I
Q
VCC1
6
RX IF IN
7
TX IF IN
8
VCC9
9
RX_EN
TX_EN
• Part of 2.4GHz Radio Chipset
• 2.4GHz PA Driver
I
TX
Q
-45°
13
14
15
16
17
18
19
20
21
22
23
24
NC
VCC5
RF LO
RF OUT
IF1 OUT-
NC
Σ
PA IN
12
+45°
NC
VCC8
Β2
VCC6
11
RF OUT
IF LO
NC
10
RF OUT
TX VGC
Functional Block Diagram
Rev A8 010418
Ordering Information
RF2938TR13
RF2938 PCBA
2.4GHz Spread-Spectrum Transceiver (Tape & Reel)
Fully Assembled Evaluation Board
RF Micro Devices, Inc.
7628 Thorndike Road
Greensboro, NC 27409, USA
Tel (336) 664 1233
Fax (336) 664 0454
http://www.rfmd.com
2-1
RF2938
Absolute Maximum Ratings
Parameter
Supply Voltage
Control Voltages
Input RF Level
LO Input Levels
Operating Ambient Temperature
Storage Temperature
Moisture Sensitivity
Parameter
Rating
Unit
-0.5 to +3.6
-0.5 to +3.6
+12
+5
-40 to +85
-40 to +150
JEDEC Level 5 @ 220°C
VDC
VDC
dBm
dBm
°C
°C
Specification
Min.
Typ.
Max.
Refer to “Handling of PSOP and PSSOP Products” on page 16-15 for
special handling information.
Refer to “Soldering Specifications” on page 16-13 for special soldering information.
Caution! ESD sensitive device.
RF Micro Devices believes the furnished information is correct and accurate
at the time of this printing. However, RF Micro Devices reserves the right to
make changes to its products without notice. RF Micro Devices does not
assume responsibility for the use of the described product(s).
Unit
T=25 °C, VCC =3.3V, Freq=280MHz,
RBW =10kΩ
Overall Receiver
RX Frequency Range
Cascaded Voltage Gain
Cascaded Noise Figure
Cascaded Input IP3
Cascaded Input IP3
RSSI Dynamic Range
RSSI Output Voltage Compliance
Condition
45
500
8 to 93
5
30
105
60
1.1 to 2.3
IF LO Leakage
Quadrature Phase Variation
Quadrature Amplitude Offset
Quadrature Amplitude Variation
MHz
dB
dB
dBµV
dBµV
dB
V
-68
±2
±5
dBm
°
+0.25
±0.25
+0.5
dB
dB
Dependent upon RX VGC
At maximum gain.
VGC <1.2V
VGC>2.0V
At VGC =1.4V
Maximum RSSI is 2.5V or VCC -0.3, whichever is less. VGC =1.4V
f=280MHz, LO Power=-10dBm
With expected LO amplitude and harmonic
content. R1=270kΩ.
Q>I
IF AMP and Quad Demod
TRANSCEIVERS
11
Gain Control Range
Noise Figure
IF Input Impedance
43
5
230-j400
75-j350
-68
-8
dB
dB
Ω
Ω
dBm
dBm
Gain Control Range
3
3
30
%
%
dB
Output Voltage
DC Output Voltage
500
1.7
mVPP
V
Input IP3
VGC <1.2V max gain, VGC>2.0V=min gain
Single Sideband
Single ended. 280MHz
Single ended. 374MHz
VGC <1.2V
VGC >2.0V
RX Baseband Amplifiers
THD
At maximum gain setting
At minimum gain setting
VGC <1.2V=max gain,
VGC >2.0V=min gain
RL >5kΩ, CL <5pF
RX Baseband Filters
Baseband Filter 3dB Bandwidth
Passband Ripple
Baseband Filter 3dB Frequency
Accuracy
Group Delay
Group Delay
Baseband Filter Ultimate Rejection
Output Impedance
2-2
1
±10
35
0.1
±30
MHz
dB
%
15
ns
400
>80
ns
dB
20
Ω
5th order Bessel LPF. Set by BW CTRL
At 35MHz, increasing as bandwidth
decreases.
At 2MHz.
Designed to drive>5kΩ, <5pF load.
Rev A8 010418
RF2938
Parameter
Specification
Min.
Typ.
Max.
Unit
Condition
Data Amplifiers
Bandwidth
Gain (Limiting mode)
Rise and Fall Time
Logic High Output
Logic Low Output
Hysteresis
40
VCC -0.3V
60
2
VCC
5
0.3
30
MHz
dB
ns
V
V
mV
Open Loop.
5pF load.
Source Current 1mA
Sink Current 1mA.
Transmit Modulator and
LPF
Filter Gain
Baseband Filter 3dB Bandwidth
Passband Ripple
Group Delay
Group Delay
Ultimate Rejection
Input Impedance
Input AC Voltage
Input DC Offset Requirement
IF Frequency Range
Output Impedance
I/Q Phase Balance
I/Q Gain Balance
Conversion Voltage Gain
0
1
35
0.1
15
400
>80
3
1.6
45
1.7
200
1.8
500
2
±2
0.5±0.25
1.1
±5
1.0
dB
MHz
dB
ns
ns
dB
kΩ
mVp-p
V
MHz
kΩ
dB
V/V
Output P1dB
-6
dBm
Carrier Output
-30
dBm
Harmonic Outputs
-30
dBc
17
1.0 to 2.0
17
230-j400
75-j350
50
+10 to +27
-9
dB
V
dB/V
Ω
Ω
Ω
dB
dBm
-4
dBm
Any setting
5th order Bessel LPF, Set by BW CTRL
At 35MHz, increasing as bandwidth
decreases.
At 2MHz.
Single ended
Linear, Single ended.
For correct operation.
Open Collector when TX on, hi-Z when off
With Current Combination into 50Ω singleended load
With Current Combination into 50Ω singleended load
Without external offset adjustments.
280MHz
Transmit VGA and
Upconverter
RF Mixer Output Impedance
VGA/Mixer Conversion Gain
VGA/Mixer Output Power
VGA/Mixer Output Power
Rev A8 010418
11
Positive Slope
TRANSCEIVERS
VGA Gain Range
VGA Input Voltage Range
VGA Gain Sensitivity
VGA Input Impedance
280MHz
374MHz
With matching elements.
With 50Ω match on the output.
1dB compression - Single Side Band,
TX GC=1.0V
1dB compression - Single Side Band,
TX GC=2.0V
2-3
RF2938
Parameter
Specification
Min.
Typ.
Max.
Unit
6
23
12
50
0
50
dBm
dB
dBm
Ω
dBm
Ω
Condition
Transmit Power Amp
Linear Output Power
Gain
Output P1dB
Output Impedance
Input IP3
Input Impedance
Power Down Control
Logical Controls “ON”
Logical Controls “OFF”
Control Input Impedance
RSSI Response Time
RX VGC Response TIme
RX EN Response TIme
TX EN Response TIme
VPD to RX Response TIme
VPD to TX Response TIme
VCC -0.3V
-0.3
0
>1
1.8
200
2
330
1.33
50
VCC +0.3V
V
0.3
V
MΩ
µs
ns
µs
ns
ms
µs
IF LO Input
Input Impedance
Input Power Range
Input Frequency
-15
90
1050-j1200
-10
0
1000
Ω
dBm
MHz
0
2400
Ω
dBm
MHz
3.6
V
Voltage supplied to the input, not to exceed
3.6V
Voltage supplied to the input.
<8pF on RSSI output.
Full step in gain, to 90% of final output level.
I/Q output VALID
To IF output VALID
To I/Q output VALID
To IF output VALID
The IF LO is divided by 2 and split into
quadrature signals to drive the frequency
mixers.
f=560MHz
peak
(2x IF Frequency)
RF LO Input
Input Impedance
Input Power Range
Input Frequency
33-j110
-15
2000
f=2.16GHz untuned.
Power Supply
TRANSCEIVERS
11
Voltage
Total Current Consumption
Sleep Mode Current
PA Driver Current
RX Current
BW (MHz)
0-11
12-20
20-30
TX Current
BW (MHz)
0-11
12-20
20-30
2-4
2.7
3.3
1
48
µA
mA
65
70
110
mA
mA
mA
95
105
115
mA
mA
mA
VCC =3.3V, Baseband BW 1MHz to 40MHz
PD=0, RX EN=1, TX EN =1
Excluding PA Driver
Rev A8 010418
RF2938
2
NC
3
PD
4
RX EN
5
TX EN
6
7
VCC1
RX IF IN
8
TX IF IN
9
10
11
VCC9
TX VGC
IF LO
12
13
VCC8
NC
14
RF OUT
Description
No internal connection. May be grounded or connected on adjacent
signal or left floating. Connect to ground for best results.
No internal connection. May be grounded or connected on adjacent
signal or left floating. Connect to ground for best results.
This pin is used to power up or down the transmit and receive baseband sections. A logic high powers up the quad demod mixers, TX and
RX GmC LPF’s, baseband VGA amps, data amps, and IF LO buffer
amp/ phase splitter. A logic low powers down the entire IC for sleep
mode. Also, see State Decode Table.
Interface Schematic
VCC
Pins
3, 4, 5
10k Ω
ESD
To Logic
Enable pin for the receiver 15dB gain IF amp and the RX VGA amp.
Powers up all receiver functions when PD is high, turns off the receiver
IF circuits when low. Also, see State Decode Table.
This pin is used to enable the transmit upconverter, buffer amps, 15db
IF amp, quad mod mixers, TX LO buffer, TX VGA, and PA driver. TX EN
is active low, when TX EN <1V, the transmit circuit is active if PD is
high. A logic high (TX EN >2V) disables the transmit IF/RF circuitry and
quad mod. Also, see State Decode Table.
Power supply for RX VGA amplifier, IC logic and RX references.
See pin 3.
IF input for receiver section. Must have DC blocking cap. The capacitor
value should be appropriate for the IF frequency. External matching to
50Ω recommended. For half duplex operation, connect RX IF IN and
TX IF IN signals together after the DC blocking caps, then run a transmission line from the output of the IF SAW. AC coupling capacitor must
be less than 150pF to prevent delay in switching RX to TX/TX to RX.
Input for the TX IF signal after SAW filter. External DC blocking cap
required. External matching to 50Ω recommended. For half duplex
operation, connect RX IF IN and TX IF IN signals together after the DC
blocking caps, then run a transmission line from the output of the IF
SAW. AC coupling capacitor must be less than 150pF to prevent delay
in switching RX to TX/TX to RX.
See pin 8.
See pin 3.
DC Block P in 7
50 Ω µstrip
IF
SAW
Filter
Pin 8
Power supply for the TX 15dB gain amp and TX VGA.
Gain control setting for the transmit VGA. Positive slope.
IF LO input. Must have DC blocking cap. The capacitor value should be
appropriate for the IF frequency. LO frequency=2xIF. Quad mod/
demod phase accuracy requires low harmonic content from IF LO, so it
is recommended to use an n=3 LPF between the IF VCO and IF LO.
This is a high impedance input and the recommended matching
approach is to simply add a 100Ω shunt resistor at this input to constrain the mismatch. This pin requires a 6.5µA DC bias current. This
can be accomplished with a 270kΩ resistor to VCC for 3.3V operation.
R ecom m en ded M atc hing
N etw ork for IF LO
C2
1 50 pF
IF V C O
IF LO
P in 1 1
Power supply for IF LO buffer and quadrature phase network.
No internal connection. May be grounded or connected on adjacent
signal or left floating. Connect to ground for best results.
This is the output transistor of the power amp stage. It is an open collector output. The output match is formed by an inductor to VCC, which
supplies DC and a series cap.
VCC
CBYP
22 nF
VCC
CBYP
22 nF
Power
Amp
Output
VCC6
PA OUT PA OUT
Pin 16
16
VCC6
Rev A8 010418
This is the output transistor of the power amp stage. It is an open collector output. The output match is formed by an inductor to VCC, which
supplies DC and a series cap.
Power supply for the PA driver amp. This inductance to ground via
decoupling, along with an internal series capacitor, forms the interstage
match.
Pin 14
14 mA
Pin 15
34 mA
PA IN
Pin 18
Bias
RF OUT
270 k Ω
1 00 Ω
From
TX RF
Image Filter
15
11
V CC
Bias
See pin 14.
See pin 14.
2-5
TRANSCEIVERS
Function
NC
µstrip
Pin
1
RF2938
Pin
17
Function
NC
18
PA IN
19
NC
20
VCC5
Description
No internal connection. May be grounded or connected on adjacent
signal or left floating. Connect to ground for best results.
Input to the power amplifier stage. This is a 50Ω input. Requires DC
blocking/tuning cap.
No internal connection. May be grounded or connected on adjacent
signal or left floating. Connect to ground for best results.
Supply for the RF LO buffer, RF upconverter and amplifier.
Interface Schematic
See pin 14.
VCC
VCC
C BYP
22 nF
To TX RF
Image Filter
CBYP
22 nF
VCC5
RF OUT
Pin 20
Pin 22
12 mA
From
TX VGA
VB
RF LO
Pin 21
CBLOCK
22 pF
From
RF VCO
TRANSCEIVERS
11
21
RF LO
22
RF OUT
23
IF1 OUT-
24
NC
25
IF1 OUT+
26
TXI BP
27
28
TXI DATA
TXQ BP
29
30
31
TXQ DATA
VCC4
I OUT
32
RXI DATA
33
Q OUT
34
RXQ DATA
35
NC
2-6
Single ended LO input for the transmit upconverter. External matching See pin 20.
to 50Ω and a DC block are required.
Upconverted Transmit signal. This 50Ω output is intended to drive an
See pin 20.
RF filter to suppress the undesired sideband, harmonics, and other outof-band mixer products.
The inverting open collector output of the quadrature modulator. This
pin needs to be externally biased and DC isolated from other parts of
IF1 OUT+
the circuit. This output can drive a Balun with IF1 OUT+, to convert to
unbalanced to drive a SAW filter. The Balun can be either broadband
(transformer) or narrowband (discrete LC matching). Alternatively, just
IF1 OUT+ can be used to drive a SAW single-ended with an RF choke
(high Z at IF) from VCC to IF1 OUT-.
No internal connection. May be grounded or connected on adjacent
signal or left floating. Connect to ground for best results.
The non-inverting open collector output of the quadrature modulator.
This pin needs to be externally biased and DC isolated from other parts
of the circuit. This output can drive a Balun with IF1 OUT-, to convert to
unbalanced to drive a SAW filter. The Balun can be either broadband
(transformer) or narrowband (discrete LC matching). Alternatively, just
IF1 OUT+ can be used to drive a SAW single-ended with an RF choke
(high Z at IF) from VCC to IF1 OUT+.
IF1 OUT-
See pin 23.
This is the in-phase modulator bypass pin. A 10nF capacitor to ground
is recommended.
I input to the baseband 5 pole Bessel LPF for the transmit modulator.
This is the quadrature modulator bypass pin. A 10nF capacitor to
ground is recommended.
Q input to the baseband 5 pole Bessel LPF for the transmit modulator.
Power supply for quadrature modulator.
Baseband analog signal output for in-phase channel.
500mVP-P linear output.
Logic-level data output for the in-phase channel. This is a digital output
signal obtained from the output of a Schmitt trigger.
0.3V to VCC3 - 0.3V swing minimum.
Baseband analog signal output for quadrature channel.
500mVP-P linear output.
Logic-level data output for the quadrature channel. This is a digital output signal obtained from the output of a Schmitt trigger.
0.3V to VCC3 - 0.3V swing minimum.
No internal connection. May be grounded or connected on adjacent
signal or left floating. Connect to ground for best results.
Rev A8 010418
RF2938
Pin
36
Function
NC
37
NC
38
RSSI
39
DCFB I
40
DCFB Q
41
VCC3
42
VREF 2
43
NC
44
BW CTRL
45
VCC2
46
VREF 1
47
48
RX VGC
NC
Pkg
Base
ESD
Description
Interface Schematic
No internal connection. May be grounded or connected on adjacent
signal or left floating. Connect to ground for best results.
No internal connection. May be grounded or connected on adjacent
signal or left floating. Connect to ground for best results.
Received signal strength indicator. Connect 8.2pF to ground. Output
impedance is 40kΩ in parallel with 2pF.
DC feedback capacitor for in-phase channel. Requires decoupling
capacitor to ground. (22nF recommended)
DC feedback capacitor for quadrature channel. Requires capacitor to
ground. (22nF recommended)
Supply for the I and Q data amps.This pin should be bypassed with a
10nF capacitor connected as direct as possible to GND3. Ground this
pin if data amps are not used.
Gain control reference voltage. No current should be drawn from this
pin (<50µA). 2.0V nominal.
No internal connection. May be grounded or connected on adjacent
signal or left floating. Connect to ground for best results.
This pin requires a resistor to ground to set the baseband LPF bandwidth of the receiver and transmit GmC filter amps.
Supply for the I and Q baseband and GmC filters. This pin should be
bypassed with a 10nF capacitor.
This is a bypass pin for the bias circuits of the GmC filter amps and for
I/Q inputs. No current should be drawn from this pin (<10µA). 1.7V
nominal.
Receiver IF and baseband amp gain control voltage. Negative slope.
No internal connection. May be grounded or connected on adjacent
signal or left floating. Connect to ground for best results.
Ground for all circuitry in the device. A very low inductance from the
base to the PCB groundplane is essential for good performance. Use
an array of vias immediately underneath the device.
This diode structure is used to provide electrostatic discharge protection to 3kV using the Human body model. The following pins are protected: 3-6, 9, 10, 12, 26-34, 38-42, 44-47.
VCC
TRANSCEIVERS
11
Rev A8 010418
2-7
RF2938
State Decode Table
Sleep Mode
Baseband Only
Receive Mode
Transmit Mode
Full Duplex
PD
0
1
1
1
1
Input Pins
RX EN
x
0
1
0
1
TX EN
x
1
1
0
0
Internally Decoded Signals
BB EN
RXIF EN
TXRF EN
0
0
0
1
0
0
1
1
0
1
0
1
1
1
1
NOTES
BB_EN Enables:
TX_LPF’s and buffers
Quad Demodulator mixers
Baseband VGA and gm-C LPF’s
Data Amplifiers
IF LO buffer/phase splitters
RXIF_EN Enables:
Front-end IF amplifier (RX)
RX IF VGA amplifiers
TXRF_EN Enables:
Front-end IF amplifier (TX)
TX VGA
RF upconverter and buffer
PA driver
RF LO buffer
11
TRANSCEIVERS
Quad Modulator mixers
2-8
Rev A8 010418
RF2938
NC
NC
RX VGC
VREF 1
VCC2
BW CTRL
NC
VREF 2
VCC3
DCFB Q
DCFB I
RSSI
NC
Detailed Functional Block Diagram
48
47
46
45
44
43
42
41
40
39
38
37
1
36
NC
35
NC
34
RXQ DATA
33
Q OUT
32
RXI DATA
31
I OUT
30
VCC4
29
TXQ DATA
28
TXQ BP
27
TXI DATA
26
TXI BP
25
IF1 OUT+
BW
Control
NC
2
PD
3
RX EN
4
DC
Feedback
Logic
gm-C
LPF
0-30 dB
+5 dB
TX EN
5
VCC1
6
DC
Feedback
REF
15 dB
RX IF IN
+6 dB
0 dB
0-30 dB
+5 dB
-6 to
37 dB
gm-C
LPF
+6 dB
0 dB
RX
TX
Bias
7
TX
15 dB
TX IF IN
8
VCC9
9
TX VGC
10
-20 to -3 dB
gm-C
LPF
Σ
gm-C
LPF
IF LO
-1.5 dB
Phase
Splitter
3.5 dB
11
TRANSCEIVERS
Β2
11
25 dB
Rev A8 010418
13
14
15
16
17
18
19
20
21
22
23
24
RF OUT
RF OUT
VCC6
NC
PA IN
NC
VCC5
RF LO
RF OUT
IF1 OUT-
NC
12
NC
VCC8
2-9
RF2938
Theory of Operation
TRANSCEIVERS
11
RECEIVER
RX IF AGC/Mixer
The front end of the IF AGC starts with a single-ended
input and a constant gain amp of 15dB. This first amp
stage sets the noise figure and input impedance of the
IF section, and its output is taken differentially. The rest
of the signal path is differential until the final baseband
output, which is converted back to single-ended. Following the front end amp are multiple stages of variable gain differential amplifiers, giving the IF signal
path a gain range of 9dB to 52dB. The noise figure (in
max gain mode) of the IF amplifiers is 5dB, which
should not degrade the system noise figure.
cutoff, and this capacitor is reused to set the DC input
level for the self-aligned data slicer.
The IF to BB mixers are double-balanced, differential
in, differential out, mixers with 5dB conversion gain.
The LO for each of these mixers is shifted 90° so that
the I and Q signals are separated in the mixers.
LO Input Buffers
RF LO Buffer
The RF LO input has a limiting amplifier before the
mixer on both the RF2444 (RX) and RF2938 (TX). This
limiting amplifier design and layout is identical on both
ICs, which will make the input impedance the same as
well. Having this amplifier between the VCO and mixer
minimizes any reverse effect the mixer has on the
VCO, expands the range of acceptable LO input levels,
and holds the LO input impedance constant when
switching between RX and TX. The LO input power
range is -18dBm to +5dBm, which should make it easy
to interface to any VCO and frequency synthesizer.
RX Baseband Amps, Filters, Data Slicers, and DC
Feedback
At baseband frequency, there are multiple AGC amplifiers offering a gain range of 0dB to 30dB. Following
these amplifiers are fully integrated gm-C low pass filters to further filter out-of-band signals and spurs that
get through the SAW filter, anti-alias the signal prior to
the A/D converter, and to band-limit the signal and
noise to achieve optimal signal-to-noise ratio. The 3dB
cut-off frequency of these low pass filters is programmable with a single external resistor, and continuously
variable from 1MHz to 35MHz. A five-pole Bessel type
filter response was chosen because it is optimal for
data systems due to its flat delay response and clean
step response. Butterworth and Chebychev type filters
ring when given a step input making them less ideal for
data systems.
The filter outputs, with +6dBm gain, drive the linear
500mVPP signal off-chip, but also connect internally to
a data slicer which squares up the signal to CMOS levels, and drives this “data” signal off-chip. This data
slicer is a high speed CMOS comparator with 30mV of
hysteresis and self-aligned input DC offset. This data
slicer can be independently disabled if only the linear
outputs are desired.
DC feedback is built into the baseband amplifier section to correct for input offsets. Large DC offsets can
arise when a mixer LO leaks to the mixer input and
then mixes with itself. DC offsets can also result from
random transistor mismatches. A large external capacitor is needed for the DC feedback to set the high pass
2-10
RSSI and VGC Operation
The receive signal path also has an RSSI output which
is the sum of both the I and Q channels. The RSSI has
about 60dBm of dynamic range and the RSSI characteristic is optimized to give best linearity and dynamic
range at a VGC setting of 1.4V. It is recommended that
the system sets VGC to 1.4V to take an RSSI reading
to make channel activity and signal level decisions,
then adjusts VGC to obtain optimum dynamic range
from the IOUT and QOUT outputs.
IF LO Buffer
The IF LO input has a limiting amplifier before the
phase splitting network to amplify the signal and help
isolate the VCO from the IC. Also, the LO input signal
must be twice the desired intermediate frequency. This
simplifies the quadrature network and helps reduce the
LO leakage onto the RX_IF input pin (since the LO
input is now at a different frequency than the IF). The
amplitude of this input needs to be between -15dBm
and 0dBm. Excessive IF LO harmonic content affects
phase balance of the modulator and demodulator so it
is recommended that a simple n=3 low pass filter is
included between VCO and IF LO input. The IF LO
input requires a DC bias current of +6.5µA. This can
be accomplished with a 270kΩ resistor to VCC for 3.3V
operation. Failing to provide this will cause a phase
imbalance in the IF LO quadrature divider of up to 8°,
which in turn causes a similar imbalance in the I/Q outputs and the TX modulator.
Rev A8 010418
RF2938
TRANSMITTER
TX LPF and Mixers
The transmit section starts with a pair of 5-pole Bessel
filters identical to the filters in the receive section and
with the same 3dB frequency. These filters pre-shape
and band-limit the digital or analog input signals prior
to the first upconversion to IF. These filters have a high
input impedance and expect an input signal of
200mVPP typical. Following these low pass filters are
the I/Q quadrature upconverter mixers. Each of these
mixers is half the size and half the current of the RF to
IF downconverter on the RF2444. Recall that this
upconverted signal may drive the same SAW filter (in
half duplex mode) as the RF2444 and therefore share
the same load. Having the sum of the two BB to IF mixers equal in size and DC current to the RF to IF mixer,
will minimize the time required to switch between RX
and TX, and will facilitate the best impedance match to
the filter.
+6dBm PA Driver
The SSB output of the upconverter is -6dBm of linear
power. The image filter should have at most 4dB of
insertion loss while removing the image, LO, 2LO and
any other spurs. The filter output should supply the PA
driver input -10dBm of power.
The PA driver is a two-stage class A amplifier with
10dB gain per stage and capable of delivering 6dBm
of linear power to a 50Ω load, and has a 1dB compression point of 12dBm. For lower power applications, this
PA driver can be used to drive a 50Ω antenna directly.
11
TRANSCEIVERS
TX VGA
The AGC after the SAW filter starts with a switch and a
constant gain amplifier of 15dB, which is identical to
the circuitry on the receive IF AGC. This was, done, as
on the RX signal path, so that the input impedance will
remain constant for different TX gain control voltages.
Following this 15dB gain amplifier is a single stage of
gain control offering 15dB gain range. The main purpose of adding this variable gain is to give the system
the flexibility to use different SAW filters and image filters with different insertion loss values. This gain could
also be adjusted real time, if desired.
TX Upconverter
The IF to RF upconverter is a double-balanced differential mixer with a differential to single-ended converter on the output to supply 0dBm peak linear power
to the image filter. The upconverted SSB signal should
have -6dBm power at this point, and the image will
have the same power, but due to the correlated nature
of the signal and image, the output must support 0dBm
of linear power to maintain linearly.
Rev A8 010418
2-11
RF2938
IL = 3 -4 dB
2.4 to 2 .48 3 G H z
RF M icro D evices
2.4 G Hz ISM Chipset
VGC1
R F 2 93 8
TQ F P -4 8 E P P
R F 24 4 4
S S O P -16 E P P
RSSI
G ain
S e le ct
OUT Q
SAW
IL = 10 dB m ax
RX
LNA
D u al G a in M o de s
-5 dB a nd +10 dB
RX
DATA Q
15 dB
15 dB G ain
IF A m p
-1 5 d B to 3 5 d B G a in
TX
OUT I
Filter
15 dB
2 .4 to 2.4 83 G H z
B as e B an d A m p.
A ctive S elec tab le LP F
(f C = 1 M H z to 4 0 M H z )
0-3 0 d B G a in
TX
D is cre te
P in D io de
R F 25 1 7
S SO P -2 8
D u al
F req ue n cy
S yn th esize r
DATA I
RF
VCO
IF
VCO
Β2
+ 4 5°
-45 °
F ilter
I IN P U T
R F 2 1 26
23 dB m or 3 3 d B m
E x tern al P A
1 5 d B G a in
R a ng e
10 dBm
P A D riv er
Σ
F ilter
S elec tab le LP F
Q IN P U T
VGC2
IL = 3 -4 d B
2.4 to 2.48 3 G H z
Figure 1. Entire Chipset Functional Block Diagram
TRANSCEIVERS
11
2-12
Rev A8 010418
RF2938
Evaluation Board Schematic
(Download Bill of Materials from www.rfmd.com.)
R6
0Ω
VCC
R7
10 Ω
C15
100 pF
VGC
C14
100 pF
C10
10 nF
R4
10 kΩ
C11
10 nF
C19
22 nF
C18
22 nF
NOTES:
1) R4 is used to set the bandwidth of the GMC Filters.
2) Pins 14 through 22 contain 2.4 GHz signals. Place tuning/bypass components
as close as possible. Make all lines on these pins 50 Ω.
3) For normal operation, move C33 to C38 and install all components with an
asterisk.
*Do not populate.
50 Ω µstrip
J15
RSSI
C17
8 pF
48
PD
47
46
45
44
43
42
40
39
38
37
1
36
TX EN
2
35
3
34
VCC
R5
10 Ω
I
15 dB
-15 dB to
35 dB Gain
31
8
L9
68 nH
R10*
0Ω
TX_EN
Baseband Amp
Active Selectable
LPF (fc=1 MHz to 40 MHz)
0-30 dB Gain
15 dB
Gain Range
RX_EN
30
15 dB
I
50 Ω µstrip
Active Selectable
LPF (fc=1 MHz to 40 MHz)
Q
C25
1 pF
50 Ω µstrip
14
15
16
17
18
19
20
21
22
23
24
2938400, Rev
-
C24
22 nF
C22
22 nF
C27
2 pF
C28
22 pF
L7
220 nH
50 Ω µstrip
C26
12 pF
50 Ω µstrip
P1
+ C12
4.7 uF
C9
10 nF
P1-3
1
VCC
2
GND
3
GC TX
L3
3.9 nH
C29
3 pF
50 Ω µstrip
50 Ω µstrip
P2-1
P2-3
TX EN
2
GND
3
RX EN
CON3
Rev A8 010418
P3
1
P3-1
P3-3
50 Ω µstrip
C30
22 pF
C32
3 pF
50 Ω µstrip
FL1*
SAWTEK
855392
J8
IF OUT
J7
RF OUT
L4
3.9 nH
CON3
P2
C31
3 pF
C33
5 pF
C38*
5 pF
VCC
P1-1
C34
22 nF
R8
1 kΩ
L1
2.7 nH
C23
22 nF
VCC
L8
39 nH
R1
270 kΩ
VCC
J9
I IN
C1
10 nF
25
13
C16
22 nF
Σ
50 Ω µstrip
C5
0.1 uF
26
12
C7
100 pF
L6
27 nH
+45
°
-45°
Β2
11
GC TX
C2
10 nF
27
10
C21
22 nF
J10
Q IN
C6
0.1 uF
28
9
VCC
J3
IF LO
VCC
C20
22 nF
29
1
PD
2
GND
3
VGC
J4
PA OUT
J5
PA IN
VCC
J6
RF LO
11
C25
22 nF
VCC
TRANSCEIVERS
50 Ω µstrip
J2
TX IF IN
7
C3
100 pF
J11
I OUT
Q
IN
C36
2 pF
J12
I DATA
50 Ω µstrip
32
5
6
R3*
0Ω
J13
Q OUT
50 Ω µstrip
C13
100 pF
L2
150 nH
50 Ω µstrip
J14
Q DATA
50 Ω µstrip
OUT
C4
100 pF
50 Ω µstrip
50 Ω µstrip
33
4
IF Amp
J1
RX IF IN
41
RX EN
CON3
2-13
RF2938
Evaluation Board Layout
Board Size 2.580” x 2.086”
Thickness: Top to Ground Laminate, 0.008”; Ground to Bottom Laminate, 0.023”;
Board Material FR-4; Multi-Layer
TRANSCEIVERS
11
2-14
Rev A8 010418
RF2938
VIN versus POUT
-3.0
VIN versus Amplitude Error
Ω , IF LO=560MHz@-10dBm)
(VCC=2.7V to 3.6V, I & Q in=1MHz, RBW=10kΩ
Ω , IF LO=560MHz@-10dBm)
(VCC=2.7V to 3.6V, I & Q in=1MHz, RBW=10kΩ
0.60
Pout, -40°C
-4.0
Ampl Err, -40°C
Ampl Err, 25°C
Pout, 25°C
-5.0
Pout, 85°C
0.50
Ampl Err, 85°C
-6.0
Amplitude Error (dB)
-7.0
POUT (dBm)
-8.0
-9.0
-10.0
-11.0
-12.0
0.40
0.30
0.20
-13.0
-14.0
0.10
-15.0
-16.0
0.00
200.0
300.0
400.0
500.0
600.0
700.0
800.0
0
100
200
VIN (mVP-P)
(VCC=3.15V, I & Q in=1MHz@100mVP-P, RBW=10kΩ
Ω , IF LO=560MHz)
500
600
700
800
LO & 2LO Out versus IF LO
(VCC=3.15V, IF LO=560MHz)
-22.0
-24.0
-26.0
-28.0
-14.6
-14.8
Pout, -40°C
Pout, 25°C
Pout, 85°C
LO Out (dBm)
-15.0
TX IF P OUT (dBm)
400
VIN (mVP-P)
TX IF POUT versus IF LO
-14.4
300
-15.2
-15.4
-15.6
-30.0
-32.0
-34.0
-36.0
-38.0
LO_out, -40°C
2LO_out, -40°C
LO_out, 25°C
2LO_out, 25°C
-40.0
-42.0
-44.0
-46.0
LO_out, 85°C
2LO_out, 85°C
-48.0
-50.0
-52.0
-54.0
-56.0
-15.8
-16.0
-16.2
-16.4
-25.0
-20.0
-15.0
-10.0
-5.0
11
-58.0
-60.0
-62.0
-25.0
0.0
IF LO (dBm)
-20.0
-15.0
-10.0
-5.0
TRANSCEIVERS
-17.0
100.0
0.0
IF LO (dBm)
RF Conversion Gain versus RF LO Level
RF LOOUT & RF 2LOOUT versus RF LO Level (VCC=3.15V,
(VCC=3.15V, Tx IF in=280MHz@-50dBm, RF LO=2160MHz)
VGC=1.5V, Tx IF in=280MHz@-50dBm, RF LO=2160MHz, 2LOOUT=4320MHz)
0.0
25C LOout
85C LOout
-5.0
-40C LOout
25C 2LOout
85C 2LOout
-10.0
20.0
19.5
19.0
18.5
18.0
17.5
-15.0
17.0
LO OUT (dBm)
Gain (dB)
16.5
16.0
15.5
25C Gain
15.0
85C Gain
14.5
-40C Gain
-20.0
-25.0
-30.0
14.0
-35.0
13.5
13.0
-40.0
12.5
12.0
-45.0
11.5
11.0
-20.0 -18.0 -16.0 -14.0 -12.0 -10.0 -8.0 -6.0 -4.0 -2.0
RF LO (dBm)
Rev A8 010418
0.0
2.0
4.0
6.0
-50.0
-20.0 -18.0 -16.0 -14.0 -12.0 -10.0 -8.0 -6.0 -4.0
-2.0
0.0
2.0
4.0
6.0
RF LO (dBm)
2-15
RF2938
RF Conversion Gain versus VGC
RF Conversion Gain versus VGC
TRANSCEIVERS
11
(VCC=3.15V, Tx IF in=280MHz@-50dBm, RF LO=2160MHz @-10dBm)
25C Gain
85C Gain
Gain (dB)
-40C
32.0
31.0
30.0
29.0
28.0
27.0
26.0
25.0
24.0
23.0
22.0
21.0
20.0
19.0
18.0
17.0
16.0
15.0
14.0
13.0
12.0
11.0
10.0
9.0
8.0
7.0
25C Gain
85C Gain
-40C Gain
0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5
0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5
VGC (VDC)
VGC (VDC)
RF Conversion Gain versus VGC
IF-RF IIP3 versus VGC
(VCC=3.6V, Tx IF in=280MHz@-50dBm, RF LO=2160MHz@-10dBm)
(VCC=2.7V, Tx IF in=12dB Below IP1dB, RF LO=2160MHz@-10dBm)
-7.0
32.0
31.0
30.0
29.0
28.0
27.0
26.0
25.0
24.0
23.0
22.0
21.0
20.0
19.0
18.0
17.0
16.0
15.0
14.0
13.0
12.0
11.0
10.0
9.0
8.0
25C Gain
-8.0
25C IIP3
85C Gain
-9.0
85C IIP3
-40C Gain
-10.0
-40C IIP3
-11.0
-12.0
-13.0
IIP3 (dBm)
Gain (dB)
Gain (dB)
(VCC=2.7V, Tx IF in=280Mhz-50dBm, RF LO=2160MHz@-10dBm)
31.0
30.0
29.0
28.0
27.0
26.0
25.0
24.0
23.0
22.0
21.0
20.0
19.0
18.0
17.0
16.0
15.0
14.0
13.0
12.0
11.0
10.0
9.0
8.0
7.0
-14.0
-15.0
-16.0
-17.0
-18.0
-19.0
-20.0
-21.0
-22.0
-23.0
0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5
0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5
VGC (VDC)
VGC (VDC)
IF-RF IIP3 versus VGC
IF-RF IIP3 versus VGC
(VCC=3.15V, Tx IF in=12dB Below IP1dB, RF LO=2160MHz@-10dBm)
(VCC=3.6V, Tx IF in=12dB Below IP1dB, RF LO=2160MHz@-10dBm)
-7.0
-7.0
-8.0
25C IIP3
-8.0
25C IIP3
-9.0
85C IIP3
-9.0
85C IIP3
-10.0
-40C IIP3
-10.0
-11.0
-11.0
-12.0
-12.0
-13.0
-14.0
IIP3 (dBm)
IIP3 (dBm)
-13.0
-15.0
-16.0
-17.0
-18.0
-14.0
-15.0
-16.0
-17.0
-18.0
-19.0
-19.0
-20.0
-20.0
-21.0
-21.0
-22.0
-22.0
-23.0
-23.0
-24.0
-24.0
2-16
-40C IIP3
-25.0
0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5
0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5
VGC (VDC)
VGC (VDC)
Rev A8 010418
RF2938
IF-RF OP1dB versus VGC
IF-RF OP1dB versus VGC
(VCC=2.7V, Tx IF in=280Mhz, RF LO=2160MHz@-10dBm)
(VCC=3.15V, Tx IF in=280MHz, RF LO=2160MHz@-10dBm)
-3.5
-4.0
25C OP1dB
-4.0
25C OP1dB
-4.5
85C OP1dB
-4.5
85C OP1dB
-5.0
-40C OP1dB
-5.0
-40C OP1dB
-5.5
-5.5
-6.0
-6.0
OP1dB (dBm)
-6.5
-7.0
-7.5
-8.0
-6.5
-7.0
-7.5
-8.0
-8.5
-8.5
-9.0
-9.0
-9.5
-9.5
-10.0
-10.0
-10.5
-10.5
0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5
0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5
VGC (VDC)
VGC (VDC)
IF-RF OP1dB versus VGC
ICC versus RBW (Temp=Ambient, VCC=3.15V, GC TX=1.5V,
(VCC=3.6V, Tx IF in=280MHz, RF LO=2160MHz@-10dBm)
-3.5
25C OP1dB
200.0
-4.0
85C OP1dB
190.0
-4.5
-40C OP1dB
180.0
-5.0
170.0
-5.5
160.0
-6.0
150.0
ICC [mA]
OP1dB (dBm)
I & Q in=100mVP-P, IF LO=-10dBm)
210.0
-3.0
-6.5
-7.0
Tx Icc
Rx Icc
Total Icc
140.0
130.0
-7.5
120.0
-8.0
110.0
100.0
-8.5
11
90.0
-9.0
80.0
-9.5
70.0
-10.0
60.0
0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5
1.0
10.0
VGC (VDC)
100.0
1000.0
RBW [kΩ]
TX 3dB BW point versus RBW (Broadband 50ΩΩ match on IF out, Temp=Ambient,
RX 3dB BW versus RBW (Temp=Ambient, VCC=3.15V, VGC=1.6V,
VCC=3.15V, GCTX=1.5V, I & Qin=100mVP-P, IFLO=560MHz @-10dBm)
RX IFIN =-67dBm, IF LO=560MHz@-10dBm)
30.0
50.0
45.0
25.0
35.0
3 dB BW Point [MHz]
3dB BW Point [MHz]
40.0
30.0
25.0
20.0
20.0
15.0
10.0
15.0
10.0
5.0
5.0
0.0
0.0
1.0
10.0
100.0
RBW [kΩ]
Rev A8 010418
1000.0
1.0
10.0
100.0
1000.0
RBW [kΩ]
2-17
TRANSCEIVERS
OP1dB (dBm)
-3.5
RF2938
RX Gain versus VGC (VCC=2.7-3.6V, RX IFIN=280.5MHz, RBW=100kΩ
Ω, I & Q
IF LO=560MHz@-10dBm, RBW=100kΩ)
Ω)
out=500mVP-P, IF LO=560MHz@-10dBm)
100.00
Icc, -40°C
Icc, +25°C
Icc, +85°C
Gain, -40°C
Gain, +25°C
Gain, +85°C
95.00
90.00
85.00
80.00
75.00
70.00
Gain (dB)
ICC (mA)
RX ICC versus VCC (VGC=1.2V to 2.0V, I & Q_out=500mVP-P,
70.00
69.50
69.00
68.50
68.00
67.50
67.00
66.50
66.00
65.50
65.00
64.50
64.00
63.50
63.00
62.50
62.00
61.50
61.00
60.50
60.00
59.50
59.00
65.00
60.00
55.00
50.00
45.00
40.00
35.00
30.00
25.00
20.00
15.00
2.7
2.8
2.9
3.0
3.1
3.2
3.3
3.4
3.5
1.2
3.6
1.3
1.4
1.5
Input P1dB versus VGC (Temp=Ambient, VCC=3.15V,
1.7
1.8
1.9
2.0
Noise Figure versus VGC (Temp=Ambient, VCC=3.15V,
RX IFIN=280.5MHz, RBW=100kΩ
Ω , IF LO=560MHz@-10dBm)
-15.00
1.6
VGC (VDC)
VCC (VDC)
RX IFIN=291MHz, RBW=5.1kΩ
Ω , IF LO=560MHz@-10dBm)
38.00
36.00
-20.00
34.00
-25.00
32.00
30.00
-35.00
28.00
-40.00
26.00
Noise Figure [dB]
Input P1dB [dBm]
-30.00
-45.00
-50.00
-55.00
-60.00
22.00
20.00
18.00
16.00
14.00
-65.00
12.00
-70.00
11
24.00
10.00
-75.00
8.00
TRANSCEIVERS
-80.00
6.00
-85.00
4.00
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2.0
1.2
1.3
1.4
1.5
VGC [VDC]
1.6
1.7
1.8
1.9
2.0
VGC [VDC]
I & Q Amplitude Balance versus VGC (VCC=3.15V, RX IFIN=280.5MHz,
I & Q Phase Balance versus VGC (VCC=2.7-3.6V,
RBW=100kΩ
Ω , I & Q out=500mVP-P, IF LO=560MHz@-10dBm)
RX IFIN=280.5MHz, RBW=100kΩ
Ω , I & Q out=500mV P-P, IF LO=560MHz@-10dBm)
12.00
3.00
Ampl_Err, -40°C
11.00
Ampl_Err, +25°C
2.50
10.00
9.00
I & Q Phase Error ( o)
I & Q Amplitude Error (dB)
Ampl_Err, +85°C
2.00
1.50
1.00
8.00
7.00
6.00
5.00
4.00
3.00
Phase Err, -40°C
2.00
0.50
Phase Err, +25°C
1.00
0.00
1.2
1.3
1.4
1.5
1.6
VGC (VDC)
2-18
Phase Err, +85°C
0.00
1.7
1.8
1.9
2.0
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
2.0
VGC (VDC)
Rev A8 010418
RF2938
RSSI versus VGC (VCC=3.15V, Temp=25oC, IF LO=-10dBm)
2.800
2.600
2.500
2.400
2.300
RSSI, VGC= 1.2V
RSSI, VGC= 1.4V
RSSI, VGC= 1.6V
RSSI, VGC= 1.8V
RSSI, VGC= 2.0V
2.200
2.100
2.000
1.900
1.800
2.700
RSSI, Vcc= 2.7V
2.600
RSSI, Vcc= 3.15V
RSSI, Vcc= 3.6V
2.500
2.400
2.300
2.200
RSSI (VDC)
RSSI (VDC)
RSSI versus VCC (VGC=1.4V, Temp=25oC, IF LO=-10dBm)
1.700
1.600
1.500
1.400
2.100
2.000
1.900
1.800
1.700
1.300
1.200
1.100
1.000
0.900
1.600
0.800
0.700
0.600
-100
1.200
1.500
1.400
1.300
1.100
-90
-80
-70
-60
-50
-40
-30
-20
-10
1.000
-100
0
-90
-80
-70
RF Lvl (dBm)
-60
-50
-40
-30
-20
-10
0
RF Lvl (dBm)
RSSI versus Temp (VCC=3.15V, VGC=1.4V, IF LO=-10dBm)
PA Gain versus VCC
(PA in=2440MHz@-30dBm)
2.600
2.500
RSSI, -40°C
2.400
RSSI, +25°C
2.300
RSSI, +85°C
24.00
23.75
23.50
23.25
2.200
2.000
Gain (dB)
1.900
1.800
1.700
1.600
85C Gain
21.75
21.50
21.25
21.00
20.75
20.50
20.25
20.00
19.75
1.500
1.400
1.300
1.200
-90
-80
-70
-60
-50
-40
-30
-20
-10
11
19.50
19.25
19.00
2.70
1.100
1.000
-100
25C Gain
0
3.15
RF Lvl (dBm)
3.60
VCC (V)
PA IIP3 versus VCC
PA OP1dB versus VCC
(PA in=2439 & 2440MHz@13dB Below IP1dB Point)
(PA in=2440MHz)
3.25
14.50
3.00
14.25
2.75
25C IIP3
2.25
-40C OP1dB
25C OP1dB
85C OP1dB
14.00
-40C IIP3
2.50
13.75
85C IIP3
2.00
OP1dB (dBm)
IIP3 (dBm)
TRANSCEIVERS
RSSI (VDC)
2.100
-40C Gain
23.00
22.75
22.50
22.25
22.00
1.75
1.50
1.25
1.00
13.50
13.25
13.00
12.75
0.75
12.50
0.50
12.25
0.25
0.00
2.70
3.15
VCC (V)
Rev A8 010418
3.60
12.00
2.70
3.15
3.60
VCC (V)
2-19
RF2938
PA 2f0 versus VCC
(PA in=2440MHz@-15dBm, 2nd Harmonic=4800MHz)
35.00
34.75
34.50
-40C 2fo
25C 2fo
85C 2fo
34.25
34.00
2f0 (dBc)
33.75
33.50
33.25
33.00
32.75
32.50
32.25
32.00
31.75
31.50
31.25
2.70
3.15
3.60
VCC (V)
TRANSCEIVERS
11
2-20
Rev A8 010418