RF Front-end IC for
5.8GHz WiFi Transmit/Receive
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Data Sheet
GC1125
1
2
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4
5
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12
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16
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PA
LNA
Log
Detector
GND
RX
GND
VCC
VDET PA_EN GND TX
N.C.
VCC
VCC
GND
GND ANTVC1
LNA_EN
GC1125
Geo-chip Green™ products are compliant
with all applicable legislation and are
halogen-free.
Description
The GC1125 is an integrated Front-End Module
(FEM) for an IEEE 802.11ax system. It includes a
highly linear 5GHz Power Amplifier (PA) with power
detector, Low Noise Amplifier (LNA) with bypass
capability, and SPDT antenna switch. The compact
form factor and integrated matching minimizes layout
area in the application.
Performance is mainly focused on optimizing the
power amplifier and Low Noise Amplifier under a 5V
supply voltage. The PA and LNA disable functions
ensure very low leakage current in off mode. An
integrated power detector is included to provide
closed-loop power control within the system.
The GC1125 is available in a 16-pin low profile
2.5x2.5x0.65mm QFN Package.
Features
⚫ 5V Supply Voltage; 3.3V Control Logic
⚫ Integrated 5GHz PA, LNA, and SPDT
Tx/Rx Switch
⚫ POUT=19.5dBm (typical) VHT80 MCS9
-36dB DEVM
⚫ POUT=18dBm (typical) VHT80 MCS11
-40dB DEVM
⚫ Bypass-able Low Noise Figure LNA
⚫ QFN: 16pin, 2.5 x2.5*0.65mm, MSL3
⚫ RoHS Compliant & Halogen Free
Applications
⚫ Wireless Routers
⚫ Access Points
⚫ Mobile Devices
⚫ Notebooks
⚫ Tablets
⚫ Internet of things
Product Highlights
⚫ Support 802.11ax
⚫ Small package
⚫ High Linearity
⚫ Low Noise Figure
Figure 1. GC1125 Block Diagram
Data Sheet
GC1125
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GND
LNA_EN
VC1
GND
ANT
DET
PA_EN
GND
TX
GND
RX
GND
VCC
VCC
VCC
GND
N.C.
1
2
3
4
12
11
10
9
5
6
7
8
16
15
14
13
Pin Description
Name
Function
GND
Ground Pin
RX
RF output from the LNA. Internally matched to 50Ω and DC blocked
VCC
5V nominal supply voltage
DET
Output of transmit power detector
PA_EN
PA control pin
TX
RF input. Internally matched to 50Ω and DC shorted.
N.C.
No connect.
ANT
RF bi-directional antenna port. Internally matched to 50Ω and DC shorted.
VC1
Rx bypass mode control line.
LNA_EN
LNA control pin
Functional State Table
Vc
1
LNA_EN¹
PA_EN²
Default State
1
1
0
Rx High Gain
1
0
0
Rx Bypass State
0
0
1
Tx
0
0
0
Sleep Mode
3
1 LNA is on while LNA_EN is high and LNA is off and in bypass mode when LNA_EN is low and VC1 is high.
2 PA_EN controls PA enable and T/R switch logic.
3 The FEM will be placed into sleep mode when all control signals are logic 0 or if they are all floating.
Absolute Maximum Ratings
Parameter
Value
Unit
DC Supply Voltage (VCC)
6
V
Control Inputs (LNA_EN, PA_EN, VC1)
3.6
V
Figure 2. GC1125 Pin Configuration