ax5051 AXSEM, ax5051 Datasheet - Page 23

• Manufacturer Part Number: ax5051
• Description: Ax5051 Radio
• Manufacturer: AXSEM

5.6.
The
external RX/TX switch is not required.
LNA
The LNA amplifies the differential RF signal from the antenna and buffers it to drive the I/Q
mixer. An external matching network is used to adapt the antenna impedance to the IC
impedance. A DC feed to the regulated supply voltage VREG must be provided at the
antenna pins. For recommendations, see section 7: Application Information.
I/Q Mixer
The RF signal from the LNA is mixed down to an IF of typically 1 MHz. I- and Q-IF signals are
buffered for the analog IF filter.
PA
In TX mode the PA drives the signal generated by the frequency generation subsystem out to
the differential antenna terminals. The output power of the PA is programmed via bits
TXRNG[3:0] in the register TXPWR. Output power as well as harmonic content will depend on
the external impedance seen by the PA, recommendations are given in the section 7:
Application Information.
5.7.
The mixer is followed by a complex band-pass IF filter, which suppresses the down-mixed
image while the wanted signal is amplified. The centre frequency of the filter is 1 MHz, with a
passband width of 1 MHz. The RF frequency generation subsystem must be programmed in
such a way that for all possible modulation schemes the IF frequency spectrum fits into the
passband of the analog filter.
5.8.
The digital IF channel filter and the demodulator extract the data bit-stream from the
incoming IF signal. They must be programmed to match the modulation scheme as well as
the data-rate. Inaccurate programming will lead to loss of sensitivity.
The channel filter offers bandwidths of 40 kHz up to 600 kHz.
For detailed instructions how to program the digital channel filter and the demodulator see
the
following table. The register setups typically must be done once at power-up of the device.
Version 1.6
AX5051
AX5051
RF Input and Output Stage (ANTP/ANTN)
Analog IF Filter
Digital IF Channel Filter and Demodulator
Programming Manual, an overview of the registers involved is given in the
uses fully differential antenna pins. RX/TX switching is handled internally, an
Circuit Description
Datasheet AX5051
23