AFE7222_15 Datasheet, PDF (72/106 Pages) Texas Instruments – Analog Front End Wideband Mixed-Signal Transceiver

AFE7222
AFE7225
SLOS711B – NOVEMBER 2011 – REVISED MARCH 2012
www.ti.com
MIXING MODE
MIXING
MIXING PATTERN⁽¹⁾
00
Normal (Low Pass, No Mixing)
Iout = { +A, +A , +A, +A }
Qout = { +B, +B , +B, +B }
01
High Pass (Fs/2)
Iout = { +A, –A , +A, –A }
Qout = { +B, –B , +B, –B }
10
+Fs/4
Iout = { +A, –B , –A, +B }
Qout = { +B, +A , –B, –A }
11
–Fs/4
Iout = { +A, +B , –A, –B }
Qout = { +B, –A , –B, +A }
(1) A and B are the inputs to the CMIX block. Iout and Qout are the outputs.
9.7 RMS POWER METER
The RX signal chain has two power meters – the coarse power meter and fine power meter.
9.7.1 Coarse Power Meter
The fine power meter estimates the total integrated power in linear scale based on a much larger set of
samples. The resulting integrated power number is stored in a register for readout. The interval time (how
often to start integration) and integration time (number of samples to integrate) is programmable. The
power meter can be configured in either real mode (where the power of each channel is calculated
individually) or in a complex mode {where the power of (I^2+Q^2) is calculated}. This is illustrated below.
I
0
Q
Power Meter 1
a
b
COARSE_PWR_OP_I (3:0)
Complex mode
Power Meter 2
a
0
b
COARSE_PWR_OP_Q (3:0)
PWR_METER_COARSE_SAMPLES(2:0)
Figure 9-3. Coarse Power Meter
9.7.2 Fine Power Meter
The fine power meter estimates the total integrated power in linear scale based on a much larger set of
samples. The resulting integrated power number is stored in a register for readout. The interval time (how
often to start integration) and integration time (number of samples to integrate) is programmable. The
power meter can be configured in either real mode (where the power of each channel is calculated
individually) or in a complex mode {where the power of (I²+Q²)is calculated}. This is illustrated below.
72
APPLICATION INFORMATION
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