CX11656 HomePlug 1.0 PHY Data Sheet
3.4.2
AGC Circuitry
The CX11656 receives 10-bit digitized samples from the D/A Converter and uses them to
adjust the Switched Gain Amplifier (SGA) gain to maintain optimum signal level at the
input of the ADC. The AGC[7:0] control bus is used to pass a Gain Control Value (GCV)
to the SGA. If the AGCENC_N input pin is low, the GCV is encoded on pins [3:0] of the
AGC[7:0] control bus. If the AGCENC_N input pin is high, the GCV is decoded on pins
[7:0] of the AGC[7:0] control bus with pins [7:4] selecting the gain switch setting for the
first stage amplifier and pins [3:0] selecting the gain switch setting for the second stage
amplifier.
RX gain control values are listed in Table 3-9.
Table 3-9. RX Gain Control Values
GCV (AGCENC_N = 0)
AGC[3:0]
0 0 0 0
GCV (AGCENC_N = 1)
Front End Gain (dB)
Notes
AGC[7:4]
0 0 0
AGC[3:0]
0 0 0
OFF
0
8
16
24
32
40
48
Mute RX during TX mode
0 0 0 1
0 0 1 0
0 0 1 1
0 1 0 0
0 1 0 1
0 1 1 0
0 1 1 1
1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1
0 0 0 1
0 0 0 1
0 0 0 1
1 0 0 0
1 0 0 0
1 0 0 0
1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1
3.4.2.1
AGC DC Characteristics
AGC DC characteristics are listed in Table 3-10.
Table 3-10. AGC DC Characteristics
Symbol
Parameter
Test Conditions
Min
2.1
Typ
Max
Unit
V
V
ns
ns
VOH
VOL
tR
High level output voltage
Low level output voltage
Rise time
1
1
1
1
0.9
5
5
tF
Fall time
Conditions:
VDD = 3.3 V, CL = 15 pF, RL = 1K Ω
3-20
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