RF_IN
LNA
FREQ
SYNTH
DIGITAL
DEMODULATOR
- Digital RSSI
- Gain Control
- Image Suppression
- Channel Filtering
- Demodulation
DIGITAL
MODULATOR
- Modulation
- Data shaping
- Power Control
BIAS
Power
Control
DIGITAL
INTERFACE
TO
m
C
C
O
N
T
R
O
L
L
O
G
IC
PA
ADC
ADC
RF_OUT
R_BIAS
XOSC_Q1 XOSC_Q2
PDO
XOSC
VC
CHP_OUT
LNA 2
0
90
:2
0
90
:2
M
u
lt
ip
le
x
e
r
Multiplexer
PA_EN
LNA_EN
PCLK
PDI
PSEL
SWRS046H – NOVEMBER 2006 – REVISED MARCH 2015
5
Detailed Description
5.1
Overview
A simplified block diagram of CC1020 is shown in
. Only signal pins are shown.
CC1020 features a low-IF receiver. The received RF signal is amplified by the low-noise amplifier (LNA
and LNA2) and down-converted in quadrature (I and Q) to the intermediate frequency (IF). At IF, the I/Q
signal is complex filtered and amplified, and then digitized by the ADCs. Automatic gain control, fine
channel filtering, demodulation and bit synchronization is performed digitally. CC1020 outputs the digital
demodulated data on the DIO pin. A synchronized data clock is available at the DCLK pin. RSSI is
available in digital format and can be read via the serial interface. The RSSI also features a programmable
carrier sense indicator.
In transmit mode, the synthesized RF frequency is fed directly to the power amplifier (PA). The RF output
is frequency shift keyed (FSK) by the digital bit stream that is fed to the DIO pin. Optionally, a Gaussian
filter can be used to obtain Gaussian FSK (GFSK).
The frequency synthesizer includes a completely on-chip LC VCO and a 90 degrees phase splitter for
generating the LO_I and LO_Q signals to the down-conversion mixers in receive mode. The VCO
operates in the frequency range 1.608 to 1.880 GHz. The CHP_OUT pin is the charge pump output and
VC is the control node of the on-chip VCO. The external loop filter is placed between these pins. A crystal
is to be connected between XOSC_Q1 and XOSC_Q2. A lock signal is available from the PLL.
The 4-wire SPI serial interface is used for configuration.
5.2
Functional Block Diagram
Figure 5-1. CC1020 Simplified Block Diagram
Copyright © 2006–2015, Texas Instruments Incorporated
Detailed Description
17
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